AP Chem 2012 Test With Answers

Chemistry Practice ExamFrom the 2012 Administration This Practice Exam from the 2012 international administration is provided by the College Board for AP Exam preparation. Teachers are permitted to download the materials and make copies to use with their students in a classroom setting only. To maintain the security of this exam, teachers should collect all materials after their administration and keep them in a secure location. Exams may not be posted on school or personal websites, nor electronically redistributed for any reason. Further distribution of these materials outside of the secure College Board site disadvantages teachers who rely on uncirculated questions for classroom testing. Any additional distribution is in violation of the College Board’s copyright policies and may result in the termination of Practice Exam access for your school as well as the removal of access to other online services such as the AP Teacher Community and Online Score Reports. Contents Exam Instructions Student Answer Sheet for the Multiple-Choice Section Section I: Multiple-Choice Questions Section II: Free-Response Questions Multiple-Choice Answer Key Free-Response Scoring Guidelines Scoring Worksheet Note: This publication shows the page numbers that appeared in the 2011−12 AP Exam Instructions book and in the actual exam. This publication was not repaginated to begin with page 1. © 2012 The College Board. College Board, Advanced Placement Program, AP, SAT and the acorn logo are registered trademarks of the College Board. All other products and services may be trademarks of their respective owners. Permission to use copyrighted College Board materials may be requested online at: www.collegeboard.com/inquiry/cbpermit.html. B Exam Instructions The following contains instructions taken from the 2011−12 AP Exam Instructions book. It is not expected that everyone will know the answers to all of the multiple-choice questions. . 2012 Section I: At a Glance Section I: Multiple Choice Booklet Instructions Total Time: Section I of this exam contains 75 multiple-choice questions. Total Time: Your total score on the multiple-choice section is based only on the 1 hour. Part B: Number of Questions: 3 Time: 40 minutes Electronic Device: None allowed Percent of Section II Score: Question 4 10% Question 5 15% Question 6 15% 43 © 2012 The College Board.org. Percent of Section II Score: Write clearly and legibly. May 7. None allowed Use your time effectively. 2012 Late-Testing Exam Date: Thursday afternoon. 35 minutes number of questions answered correctly. completely fill Writing Instrument: in the corresponding circle on the answer sheet. Manage your time carefully. May 24. If you change an answer. No credit will be given for anything written in this exam Percent of Total Score: booklet. you may not 3 begin working on Part B until the proctor tells you to do so. AP® Chemistry Exam Regularly Scheduled Exam Date: Monday morning. If you finish Part B Question 3 20% before time is called. Time: you may proceed freely from one question to the next within each part. Fill in 1 hour. However. 6 Percent of Total Score: 50% Writing Instrument: Section II: Free Response Booklet Instructions Either pencil or pen with black or dark blue ink The questions for Part A and Part B are printed in this booklet. but you must write your answers in Calculator allowed the areas designated for each response. Number of Questions: Indicate all of your answers to the multiple-choice questions on the 75 answer sheet. Pages containing a periodic table. 30 minutes only the circles for numbers 1 through 75 of the answer sheet. erased or Question 1 20% crossed-out work will not be scored. you may go back to Part A. Give only one answer Pencil required to each question. After 50% you have decided which of the suggested answers is best. working as quickly as you can without losing accuracy. Do Question 2 20% not spend too much time on any one question. Points are not deducted for Number of Questions: incorrect answers or unanswered questions. Number of Questions: The proctor will announce the times for Part A and Part B.collegeboard. Do not spend too much time on any one question. be sure that the previous Electronic Device: mark is erased completely. Go on to other questions and come back to the ones you have not answered if Section II: At a Glance you have time. reduction potentials. but you may use the booklet for notes or scratch work. Visit the College Board on the Web: www. 55 minutes You may use the pages that the questions are printed on to organize Electronic Device: your answers or for scratch work. and lists containing Part A: equations and constants are also printed in this booklet. Cross out any errors you make. but you may NOT use a calculator. and you will be taking the AP Chemistry Exam. date. he or she must hand copy. students may have no more than two calculators on their desks. Part A only. calculators may not be shared. refer to the calculator policy for Chemistry on pages 40–42 of the 2011-12 AP Coordinator’s Manual. and you will be taking the AP Chemistry Exam. Put the white seals aside. you agree to all of the AP Program’s policies and procedures outlined in the 2011-12 Bulletin for AP Students and Parents. but do not open the booklet or the shrinkwrapped Section II materials. . If you are giving the regularly scheduled exam. . you will open the packet that contains your exam materials. If a student does not have an appropriate calculator. Before starting the exam. During the administration of Section II. and sign the release statement on page 41 of the 2011-12 AP Coordinator’s Manual. you may provide one from your supply. SECTION I: Multiple Choice ! DGeneral o not begin the exam instructions below until you have completed the appropriate Instructions for your group. Make sure you begin the exam at the designated time. 2 pencils with erasers • AP Student Packs • Extra pens with black or dark blue ink • 2011-12 AP Coordinator’s Manual • Extra paper • This book — AP Exam Instructions • Stapler • School Code and Home-School/Self. . or does not want to use a calculator at all. If the student does not want to use the calculator you provide. say: It is Monday morning. say: It is Thursday afternoon. Visit the College Board on the Web: www. Calculator memories do not need to be cleared before or after the exam. 44 © 2012 The College Board. .collegeboard. If you are giving the alternate exam for late testing.Chemistry What Proctors Need to Bring to This Exam • Exam packets • Pencil sharpener • Answer sheets • Extra No. In a moment.org. You may now remove the shrinkwrap from your exam packet and take out the Section I booklet. • Watch Study Codes • Signs for the door to the testing room • Extra calculators – “Exam in Progress” – “Cell phones are prohibited in the testing room” Students are permitted to use calculators to answer some of the questions in Section II of the AP Chemistry Exam. May 7. Calculators with QWERTY keyboards are prohibited. May 24. By opening this packet. Open your Section I booklet and begin. Look up when you have finished. If you disclose these questions through any means. including your teacher and other students. AP Exam Instructions Look at page 1 of your answer sheet and locate the dark blue box near the top right-hand corner that states. . . Note Stop Time here . . Collect an answer sheet from each student. Make sure you have your AP number label and an AP Exam label on page 1 of your answer sheet. . Check that students are marking their answers in pencil on their answer sheets. but you may use the margins or any blank space in the exam booklet for scratch work. . . one response per question. Remove the white seals from the backing and press one on each area of your exam booklet cover marked “PLACE SEAL HERE. Mark all of your responses on your answer sheet. When you have 45 © 2012 The College Board. Please put your calculators under your chair. Visit the College Board on the Web: www. . You have 1 hour and 30 minutes for this section. . . Are there any questions? . No credit will be given for anything written in the exam booklet. . Are there any questions? .”. Completely fill in the circles. do so carefully and completely. Sign your name. Are there any questions? . Close your booklet and put your answer sheet on your desk. . Scratch paper is not allowed. . Now read the statements on the front cover of Section I and look up when you have finished. . Check that each answer sheet has an AP number label and an AP Exam label. and that they are not looking at their shrinkwrapped Section II booklets. say: CHEMISTRY Stop working. . Calculators are not allowed for this section.org. Now look at the front cover of your exam booklet and locate the AP Exam label near the top left of the cover. . You must complete the answer sheet using a No. . and write today’s date. If you need to erase. . After 1 hour and 30 minutes. Carefully peel off the AP Exam label and place it on your answer sheet on the dark blue box that we just identified. . I will now collect your answer sheet. Then say: Now you must seal your exam booklet. 2 pencil only.” Fold each seal over the back cover. . . Now print your full legal name where indicated. “Take the AP Exam label from your Section I booklet and place the label here. Section I is the multiple-choice portion of the exam. . Turn to the back cover and read it completely. . . your AP Exam score will be canceled.collegeboard. You may never discuss these specific multiple-choice questions at any time in any form with anyone. 12 9 Note Start Time here 6 3 . Are there any questions? . . face up. Look up when you have finished. . . Using your pen. . Are there any questions? . place the booklet on your desk. middle and last initials of your legal name in the boxes and print today’s date where indicated. Failure to adhere to any of these rules could result in cancellation of your score. say: May I have everyone’s attention? Place your Student Pack on your desk. Read the bulleted statements on the front cover of the exam booklet. Look up when you have finished. .org. . SECTION II: Free Response After the break. In Item 3. . or access any electronic or communication device. write your AP number in the box. Now place an AP number label on the shaded box. You are not allowed to consult teachers. . . There is a 10-minute break between Sections I and II. . . Are there any questions? . . You may now remove the shrinkwrap from the Section II packet. but do not open the exam booklet until you are told to do so.Chemistry finished. other students. This constitutes your signature and your agreement to the statements on the front cover. .collegeboard. If you don’t have any AP number labels. write the school code you printed on the front of your Student Pack in the boxes. . say: Please listen carefully to these instructions before we take a 10-minute break. . Leave your shrinkwrapped Section II packet on top of your desk during the break. . . . face up. Read the last statement. Look up when you have finished. . Turn to the back cover and read Item 1 under “Important Identification Information. . check email. or textbooks about the exam during the break. In Item 2.” Print the first two letters of your last name and the first letter of your first name in the boxes. . Everything you placed under your chair at the beginning of the exam must stay there. Check that each student has signed the front cover of the sealed Section I booklet. use a social networking site. . . print your date of birth in the boxes. . I will now collect your Section I booklet. you are not allowed to discuss the multiple-choice section of this exam. print the first. Testing will resume at . . . . 46 © 2012 The College Board. Remember. Read Item 4. When all Section I materials have been collected and accounted for and you are ready for the break. send text messages. . . Look up when you have finished. . . . . . Visit the College Board on the Web: www. . . . . . You may not make phone calls. . 12 9 6 3 You may begin your break. . be sure to write only your AP number and the number of the question you are working on. You must write your answers in the exam booklet using a pen or a No. Section II has two parts. 47 © 2012 The College Board. Calculators are not allowed for Part B. read the information on the back cover of the exam booklet. Do not open the exam booklet until you are told to do so. Look up when you have finished. place your Student Pack under your chair now. . . . raise your hand. . You must answer Questions 4. If you have no other AP Exams to take. . . . . While Student Packs are being collected. . Please put your calculators under your chair. Do not begin Part B at this time. If you use a pencil. You may get your calculators from under your chair and place them on your desk. . You may begin Part B. . you may go back to Part A. Then say: Are there any questions? . be sure that your writing is dark enough to be easily read. At the top of each extra piece of paper you use. Pages in Part B are easily identifiable by a row of large bold letter B’s at the top of each page. . You must answer Questions 1. . but CHEMISTRY you may not use your calculators. After 45 minutes. Note Stop Time here . Collect the Student Packs. Visit the College Board on the Web: www. Do not begin Part B until you are told to do so. . be sure that your writing is dark enough to be easily read. . . and 6. You may keep it only if you are not taking any other AP Exams this year. and may proceed freely from one question to the next within each part. and 3. Are there any questions? .collegeboard. . Proctors should also make sure that calculators’ infrared ports are not facing each other and that students are not sharing calculators. 2 pencil. You have 40 minutes to complete Part B. You are responsible for pacing yourself. Calculators are allowed for Part A. Open the exam booklet and begin Part A. If you use a pencil. If you need more paper during the exam. You have 55 minutes to complete Part A. Are there any questions? . Check that students are writing their answers in their exam booklets and that they are not working on Part B. . .org. 2. say: Stop working on Part A. 5. AP Exam Instructions I need to collect the Student Pack from anyone who will be taking another AP Exam. Write your answers legibly using either a pen with black or dark blue ink or a No. Do not write your name. say: There are 10 minutes remaining in Part A. 2 pencil. 12 9 6Note Start Time here 3 . After 10 minutes. If you finish Part B before time is called. Then say: You are now dismissed. You should receive your score report in the mail about the third week of July. . say: Please remember to take your AP number card with you. . Check that students are writing their answers in their exam booklets and that they are not using calculators. face up. without talking. have those students staple the extra sheet/s to the first page corresponding to that question in their exam booklets. If you are giving the regularly scheduled exam. say: There are 10 minutes remaining in Part B. . . If any students used extra paper for the free-response section. say: None of the questions in this exam may ever be discussed or shared in any way at any time. Check for the following: • • Exam booklet front cover: The student placed an AP number label on the shaded box. After 10 minutes. Then say: Remain in your seat. while the exam materials are collected. • • Exam booklet back cover: The student completed the “Important Identification Information” area. 48 © 2012 The College Board. return to students any electronic devices you may have collected before the start of the exam. Place it on your desk. If any students completed the AP number card at the beginning of this exam. Collect a Section II booklet from each student. say: Stop working and close your exam booklet.org. When all exam materials have been collected and accounted for.collegeboard. and printed his or her initials and today’s date. You should receive your score report in the mail about the third week of July. say: You may not discuss these specific free-response questions with anyone unless they are released on the College Board website in about two days. .Chemistry 12 9 6Note Start Time here 3 . . . Note Stop Time here . Visit the College Board on the Web: www. If you are giving the alternate exam for late testing. After 30 minutes. Before storing materials. . CHEMISTRY 49 © 2012 The College Board.org. See “Post-Exam Activities” in the 2011-12 AP Coordinator’s Manual. check the “School Use Only” section on page 1 of the answer sheet and: • • Fill in the appropriate section number circle in order to view a separate AP Instructional Planning Report (for regularly scheduled exams only) or Subject Score Roster at the class section or teacher level. Visit the College Board on the Web: www. • • Check your list of students who are eligible for fee reductions and fill in the appropriate circle on their registration answer sheets. AP Exam Instructions All exam materials should be put in secure storage until they are returned to the AP Program after your school’s last administration.collegeboard. ) . and may differ from one used in an actual exam. B Student Answer Sheet for the Multiple-Choice Section Use this section to capture student responses. (Note that the following answer sheet is a sample. universities and government scholarship T T T T T T T T T T T T T T T T T T T T T T T T T T T T Sep 7 7 7 12th 7 7 7 7 7 7 7 7 7 programs interested in students like me. Month AM PM S Sign your legal name as it will appear on your college applications. ETHNICITY/RACE Father/ Mother/ X X X X X X X X X X X X X X X X X X X X X X X X X X X X Male Guardian Female Guardian Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y O. MULTIPLE-CHOICE BOOKLET C. WHICH LANGUAGE American Indian or Alaska Native Grade school Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z DO YOU KNOW BEST? Asian. SOCIAL SECURITY M. CURRENT 1 1 1 1 1 1 1 1 1 Summer 2014 GRADE O O O O O O O O O O O O O O O O O O O O O O O O O O O O Apr 2 2 2 2 LEVEL 2 2 2 2 2 2 2 2 2 Undecided 2015 P P P P P P P P P P P P P P P P P P P P P P P P P P P P May 3 3 3 3 Pre-9th 3 3 3 3 3 3 3 3 3 Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Jun 4 4 4 9th 4 4 4 4 4 4 4 4 4 N.g. Date A. II. SEX L. STUDENT SEARCH SERVICE® R R R R R R R R R R R R R R R R R R R R R R R R R R R R Jul 5 5 5 10th 5 5 5 5 5 5 5 5 5 I want the College Board to send S S S S S S S S S S S S S S S S S S S S S S S S S S S S Aug 6 6 6 11th 6 6 6 6 6 6 6 6 6 information about me to colleges. computer. B123456789T NAME AND EXAM AREA — COMPLETE THIS AREA AT EVERY EXAM. SIGNATURE 0 0 0 0 0 0 0 0 0 0 0 0 6 12 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 B. ONLINE multiple-choice booklet when asked to do so. U U U U U U U U U U U U U U U U U U U U U U U U U U U U Oct 8 8 8 Post-12th 8 8 8 8 8 8 8 8 8 Yes No V V V V V V V V V V V V V V V V V V V V V V V V V V V V Nov 9 9 9 9 9 9 9 9 9 9 9 9 W W W W W W W W W W W W W W W W W W W W W W W W W W W W Dec 00657-88488 • UNLPDF212 Q. DATE TIME SERIAL NUMBER CODE including using testing accommodations (e. J J J J J J J J J J J J J J J J J J J J J J J J J J J J I. AP EXAM I AM TAKING Print Exam Name: Print Form: Print Form Code: G G G G G G G G G G G G G G G G G G G G G G G G G G G G USING THIS ANSWER SHEET H H H H H H H H H H H H H H H H H H H H H H H H H H H H I I I I I I I I I I I I I I I I I I I I I I I I I I I I STUDENT INFORMATION AREA — COMPLETE THIS AREA ONLY ONCE. PAGE 1 Take an AP Number label from Take the AP Exam label from your AP Student Pack and your Section I booklet and 2012 Answer Sheet place the label here. Latino or Associate or two-year degree Section Number Another language Latin American Exam 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 White Bachelor’s or four-year degree Q3428/1-4 Fee Reduction Granted 0 1 2 3 4 5 6 7 8 9 Other Some graduate or professional school Exam 762000 1 Option 1 2 Option 2 0 1 2 3 4 5 6 7 8 9 Graduate or professional degree . Asian American or Some high school Pacific Islander – – – – – – – – – – – – – – – – – – – – – – – English Black or African American High school diploma or equivalent English and Mexican or Mexican American Business or trade school another language SCHOOL USE ONLY ETS USE ONLY about the same Puerto Rican Some college 0 1 2 3 4 5 6 7 8 9 Other Hispanic. YOUR AP NUMBER START PROVIDER section. place the label here. EXPECTED DATE OF NUMBER (Optional) COLLEGE ENTRANCE K K K K K K K K K K K K K K K K K K K K K K K K K K K K Month Day Year Female L L L L L L L L L L L L L L L L L L L L L L L L L L L L Jan Male Fall 2012 M M M M M M M M M M M M M M M M M M M M M M M M M M M M Feb 0 0 0 0 0 0 0 0 0 0 0 0 0 Winter/Spring 2013 N N N N N N N N N N N N N N N N N N N N N N N N N N N N Mar 1 1 1 1 K. extended time. I will seal the E. DATE OF BIRTH J. Jr. etc. LEGAL NAME Omit apostrophes. USE NO.. EXAM F.. PARENTAL EDUCATION LEVEL P. I will allow no one else to see the multiple-choice questions.) only if I have been preapproved by College Board Services for Students with Disabilities. EXAM G. 2 PENCIL ONLY To maintain the security of the exam and the validity of my AP score. I am aware of and agree to the AP Program’s policies and procedures as outlined in the 2011-12 Bulletin for AP Students and Parents. and I will not discuss these questions with anyone at any time after the completion of the D. 2 2 2 2 2 2 2 2 2 2 2 8 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Legal Last Name — First 15 Letters Legal First Name — First 12 Letters MI 3 3 3 3 3 3 3 3 3 3 3 9 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 10 4 4 4 4 4 4 4 4 4 4 4 4 4 4 A A A A A A A A A A A A A A A A A A A A A A A A A A A A 5 5 5 5 5 5 5 5 5 5 11 5 5 5 5 5 5 5 5 5 5 5 5 5 5 B B B B B B B B B B B B B B B B B B B B B B B B B B B B 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 C C C C C C C C C C C C C C C C C C C C C C C C C C C C 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 D D D D D D D D D D D D D D D D D D D D D D D D D D D D 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 E E E E E E E E E E E E E E E E E E E E E E E E E E E E 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 F F F F F F F F F F F F F F F F F F F F F F F F F F F F H. Have you lived or studied for one month or more in a country where the language of the 2. 62. 1. Your responses will not affect your score. If this answer sheet is for the French Language and Culture. Use only No. After you have determined your response. or Spanish Literature Exam. If a question has only four answer options. be sure to completely fill in the corresponding circle next to the number of the question you are answering. SURVEY QUESTIONS — Answer the survey questions in the AP Student Pack. Any improper gridding may affect your score. Answers written in the multiple-choice booklet will not be scored. so erase carefully and completely.PAGE 2 R. German Language and Culture. Do not put responses to exam questions in this section. 1 A B C D E 26 A B C D E 51 A B C D E 2 A B C D E 27 A B C D E 52 A B C D E 3 A B C D E 28 A B C D E 53 A B C D E 4 A B C D E 29 A B C D E 54 A B C D E 5 A B C D E 30 A B C D E 55 A B C D E 6 A B C D E 31 A B C D E 56 A B C D E 7 A B C D E 32 A B C D E 57 A B C D E 8 A B C D E 33 A B C D E 58 A B C D E 9 A B C D E 34 A B C D E 59 A B C D E 10 A B C D E 35 A B C D E 60 A B C D E 11 A B C D E 36 A B C D E 61 A B C D E 12 A B C D E 37 A B C D E 62 A B C D E 13 A B C D E 38 A B C D E 63 A B C D E 14 A B C D E 39 A B C D E 64 A B C D E 15 A B C D E 40 A B C D E 65 A B C D E 16 A B C D E 41 A B C D E 66 A B C D E 17 A B C D E 42 A B C D E 67 A B C D E 18 A B C D E 43 A B C D E 68 A B C D E 19 A B C D E 44 A B C D E 69 A B C D E 20 A B C D E 45 A B C D E 70 A B C D E 21 A B C D E 46 A B C D E 71 A B C D E 22 A B C D E 47 A B C D E 72 A B C D E 23 A B C D E 48 A B C D E 73 A B C D E 24 A B C D E 49 A B C D E 74 A B C D E 25 A B C D E 50 A B C D E 75 A B C D E R W O R W O OTHER ETS PT02 TOTAL 48. 87 ONLY PT03 PT04 DO NOT WRITE IN THIS AREA . 55. 1 A B C D E F G H I 4 A B C D E F G H I 7 A B C D E F G H I 2 A B C D E F G H I 5 A B C D E F G H I 8 A B C D E F G H I 3 A B C D E F G H I 6 A B C D E F G H I 9 A B C D E F G H I S. Spanish Language. USE 75. Do you regularly speak or hear the language at home? exam you are now taking is spoken? Yes No Yes No Indicate your answers to the exam questions in this section. 2 pencils to mark your answers on pages 2 and 3 (one response per question). Italian Language and Culture. Your answer sheet will be scored by machine. LANGUAGE — Do not complete this section unless instructed to do so. do not mark option E. please answer the following questions. Stray marks and smudges could be read as answers. DO NOT WRITE IN THIS AREA . PAGE 3 QUESTIONS 76–120 Be sure each mark is dark and completely fills the circle. 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PAGE 4 T. COLLEGE TO RECEIVE YOUR AP SCORE REPORT 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 AL IA MN NY VA 2 2 2 2 2 2 2 2 2 COLLEGE 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 AR ID MO OH VT 3 3 3 3 3 3 3 3 3 CODE Using the college code listed in the AP Student Pack. YOUR MAILING ADDRESS Use the address abbreviations from your AP Student Pack. Fill in only one circle per column. Address City State or Province Country ZIP or Postal Code 8 8 8 8 Country 9 9 9 9 By providing your email address. AREA CODE AND PHONE COUNTRY NUMBER STREET ADDRESS (include street number. EMAIL ADDRESS permission to use your email in accordance with the policies in the 2011-12 Bulletin for AP Students and Parents. etc. U. FOR STUDENTS OUTSIDE THE UNITED STATES ONLY If the address gridded above is not complete enough for delivery of your 7 7 7 7 score report. Indicate a space in your address by leaving a blank box. .GO ON TO THE NEXT PAGE. B Section I: Multiple-Choice Questions This is the multiple-choice section of the 2012 AP exam. It includes cover material and other administrative instructions to help familiarize students with the mechanics of the exam.) . (Note that future exams may differ in look from the following content. working as quickly as you can without losing accuracy. but you may use the booklet Percent of Total Score for notes or scratch work. Points are not deducted for incorrect answers or unanswered questions. Go on to other questions and come back to the ones you have not answered if you have time. Instructions At a Glance Section I of this exam contains 75 multiple-choice questions. Electronic Device None allowed Use your time effectively. Form I Form Code 4IBP4-S Minimum 20% post-consumer waste 25 . Give only one answer to Writing Instrument each question. Fill in only the circles for Total Time numbers 1 through 75 of the answer sheet. Here is a sample question and answer. Your total score on the multiple-choice section is based only on the number of questions answered correctly. Do not spend too much time on any one question. 1 hour. be sure that the previous mark is erased Pencil required completely. After you have decided which of the suggested answers is best. If you change an answer. ® AP Chemistry Exam SECTION I: Multiple Choice 2012 DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. 30 minutes Number of Questions Indicate all of your answers to the multiple-choice questions on the answer sheet. 50% completely fill in the corresponding circle on the answer sheet. It is not expected that everyone will know the answers to all of the multiple-choice questions. No 75 credit will be given for anything written in this exam booklet. MATERIAL IN THE FOLLOWING TABLE MAY BE USEFUL IN ANSWERING THE QUESTIONS IN THIS SECTION OF THE EXAMINATION. GO ON TO THE NEXT PAGE. -2- . kilojoule(s) R = molar gas constant V = volt(s) n = number of moles mol = mole(s) M= molar m= molal Part A Directions: Each set of lettered choices below refers to the numbered statements immediately following it. Is best represented by two or more resonance forms 3. mL = liter(s). -3- . Throughout the test the following symbols have the definitions specified unless otherwise noted. Select the one lettered choice that best fits each statement and then fill in the corresponding circle on the answer sheet. GO ON TO THE NEXT PAGE. Note: For all questions. Is the molecule in which the intramolecular forces are strongest Unauthorized copying or reuse of any part of this page is illegal. the pressure is 1. (A) BeCl2 (B) SO2 (C) N2 (D) O2 (E) F2 1. Is a polar molecule 2. A choice may be used once. milliliter(s) P = pressure g = gram(s) V = volume nm = nanometer(s) S = entropy atm = atmosphere(s) H= enthalpy mm Hg = millimeters of mercury G= Gibbs free energy J. assume that the temperature is 298 K.00 atmosphere. or not at all in each set. more than once. kJ = joule(s). T = temperature L. CHEMISTRY Section I Time— 1 hour and 30 minutes NO CALCULATOR MAY BE USED WITH SECTION I. Questions 1-3 refer to the following gaseous molecules. and solutions are aqueous unless otherwise specified. NaC2H3O2(s). Occurs when Al(s) and CuCl 2(aq) are mixed 207 into 82 Pb 8. (A) Alpha-particle emission (B) Beta-particle emission (A) Oxidation-reduction reaction (C) Electron capture (B) Brønsted-Lowry acid-base reaction (D) Gamma-ray emission (C) Sublimation (E) Nuclear fission (D) Dehydration (E) Precipitation 4. Occurs when solid sodium acetate. Occurs when aqueous solutions of ammonia and vinegar are mixed 207 5. GO ON TO THE NEXT PAGE. is added to water Unauthorized copying or reuse of any part of this page is illegal.Questions 4-5 Questions 6-8 refer to the following types of chemical or physical changes. -4- . Is the major process by which nuclei lose excess energy without a change in atomic number 6. Accounts for the transformation of 81 T1 7. Has the lowest first-ionization energy 9. Have lowest root-mean-square speed Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE.Questions 9-10 refer to the following gas molecules Questions 11-13 at the conditions indicated. -5- . (A) Cs (A) H2(g) molecules at 10-3 atm and 200∞C (B) Ag (C) Pb (B) O2(g) molecules at 20 atm and 200∞C (D) Br (C) SO2(g) molecules at 20 atm and 200∞C (E) Se (D) NH3(g) molecules at 20 atm and 200∞C (E) NH3(g) molecules at 20 atm and 300∞C 11. Has the highest electronegativity 12. Behave most like an ideal gas 13. Has the largest atomic radius 10. Questions 14-16 refer to the following compounds. Dissolves in water to form an acidic solution 16. Is isomeric with CH3CH2CHO 15. -6- . (A) CH3CH2CH2CH3 (B) CH3CH2CH2OH (C) CH3COCH3 (D) CH3COOH (E) CH3CH2CH2NH2 14. GO ON TO THE NEXT PAGE. Is the LEAST soluble in water Unauthorized copying or reuse of any part of this page is illegal. 0 × 10 -4 mol L-1 s-1 (B) 0. A certain crystalline substance that has a low 20. GO ON TO THE NEXT PAGE. the sample weighed 1. the initial rate nitrate. when cooled to room (B) HClO4 temperature.1632 g. Which of the following is a weak acid in aqueous solution? 22.010 M (A) 7.30 M (D) 5. the (E) H2SO4 sample weighed 1.10 M (C) 2. (D) Reheat the sample until its mass is constant.1857 g.6 × 10 -3 mol L-1 s-1 (E) 1.4 × 10 -3 mol L-1 s-1 (D) 0. there are solution or when melted. (E) Use the average of the mass values obtained after the two heatings to calculate the percentage of water in the hydrated salt. Solid Al(NO3)3 is added to distilled water to X + 2Y Æ Z + 3Q produce a solution in which the concentration of 21.02 × 1023 hydrogen atoms (B) 6. a student heated a 1. in this solution? What was the initial rate of decrease in [Y] ? (A) 0. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet.2346 g sample of the salt for 30 minutes. tion of aluminum ion.8 × 10 -3 mol L-1 s-1 (E) 0. Part B Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. In 1.1 × 10 -2 mol L-1 s-1 19. [Al3+]. To determine the percentage of water in a (A) HCl hydrated salt. is 0. -7- . 17.00 mol of potassium zirconium sulfate melting point does not conduct electricity in trihydrate. [NO3-].10 M. Which of the following should the student do next? (A) Use the smallest mass value to calculate the percentage of water in the hydrated salt.8 × 10 -3 mol L-1 s-1. What is the concentra- of decrease in [X] was 2. (B) Repeat the experiment with a new sample of the same mass and average the results.02 × 1023 potassium atoms (C) a polymer (D) 4 moles of oxygen atoms (D) an ionic solid (E) 4 moles of zirconium atoms (E) a molecular solid 18. (C) Repeat the experiment with a new sample that has a different mass. After (C) HNO3 the sample was heated for an additional 10 min- (D) H2S utes and again cooled to room temperature.033 M (C) 0. This substance is likely to be (A) 3 × 6. K4Zr(SO4)4 ⴢ 3 H2O.066 M (B) 1. For the reaction represented above. Unauthorized copying or reuse of any part of this page is illegal.02 × 1023 sulfur atoms (A) a covalent network solid (B) a metallic solid (C) 4 × 6. 40 mol of Al with 0. What is the maximum number of moles of Al2O3 that can be produced by the reaction of 0.8 atm (E) 16 atm 28. (B) All atoms of a given element must have the same number of protons. (C) Most of the volume of an atom contains only electrons.0 atm (C) 6. The substance under the conditions NH3(aq) + HCl(aq) Æ̈ NH4+(aq) + Cl -(aq) corresponding to point X on the diagram is cooled to 40∞C while the pressure remains 24.20 mol (C) 0. As the substance cools. Shown above is the phase diagram of a pure substance.27 mol (D) 0.40 mol Unauthorized copying or reuse of any part of this page is illegal. Which of the following statements about atoms is NOT correct? (A) Atoms are electrically neutral because they have the same number of protons and electrons.33 mol (E) 0. (D) The nucleus is positively charged. the final pressure in the (B) S(s) + O2(g) Æ SO2(g) container at 0°C is (C) 2 F2(g) + O2(g) Æ 2 OF2(g) (A) 2. and electrons. both the following reactions EXCEPT at 0°C and 1. L of N2(g). Oxygen is acting as an oxidizing agent in all of 25. -8- .0 L rigid container.10 mol (B) 0. neutrons.0 atm (D) 2 Na(s) + O2(g) Æ Na2O2(s) (B) 4. The Brønsted-Lowry bases in the reaction constant. are pumped into an evacuated (A) 2 C(s) + O2(g) Æ 2 CO(g) 4. (E) Almost all of the mass of an atom is in the nucleus.40 mol of O2 ? (A) 0. GO ON TO THE NEXT PAGE. 26. When 6.0 L of He(g) and 10.0 atm.23.4 atm (E) 2 Mg(s) + O2(g) Æ 2 MgO(s) (D) 8. the phase of represented above are the substance changes from (A) NH3(aq) and NH4+(aq) (A) gas to liquid to solid (B) NH3(aq) and Cl -(aq) (B) gas to solid to liquid (C) NH3(aq) and HCl(aq) (C) solid to liquid to gas (D) liquid to solid to gas (D) HCl(aq) and NH4+(aq) (E) liquid to gas to solid (E) HCl(aq) and Cl -(aq) 27. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE.0 mm Hg (D) 5 (E) 26.0 mm Hg.900 ? for O2(g) is (A) 1.1 M solution of which of the following is water? colorless? (A) NiS (A) MgCl2 (B) MgCl2 (B) Ni(NO3 )2 (C) K2CrO4 (C) Na2CrO4 (D) Al2(SO4)3 (D) KMnO4 (E) Pb(NO3)2 (E) CuSO4 34. Which of the following is the best piece of 31.7 mm Hg (E) 6 33. When the equation for the reaction represented pressure at 25°C of an ideal solution of a above is balanced and all coefficients are reduced nonvolatile nonelectrolyte in which the mole to the lowest whole-number terms. -9- .6 mm Hg (C) 3 (D) 24. Under which of the following conditions can an laboratory glassware for preparing 500. Which of the following salts is LEAST soluble in 30.48 mm Hg (A) 1 (B) 2. the coefficient fraction of water is 0. The vapor pressure of pure water at 25°C is 24.40 mm Hg (B) 2 (C) 21. What is the expected vapor 29. A 0.… C3H8(g) + … O2(g) Æ … H2O(g) + … CO2(g) 32.0 mL of endothermic reaction be thermodynamically an aqueous solution of a solid? favorable? (A) Volumetric flask (A) ΔG is positive (B) Erlenmeyer flask (B) ΔS is negative (C) Test tube (D) Graduated beaker (C) TΔS > Δ H (E) Graduated cylinder (D) TΔS = 0 (E) There are no conditions under which an endothermic reaction can be thermodynamically favorable. Unauthorized copying or reuse of any part of this page is illegal. were equal. Which of (A) The concentration of N 2 decreased. 35. (E) The amount of H2 will decrease. (C) The total pressure in the container will (E) The rate of formation of NH 3 molecules was decrease. More NH 3 gas is added to the system at time t2 between time t1 and time t2 ? while the temperature is held constant. (B) The value of the equilibrium constant will (D) The rates of the forward and reverse reactions decrease. N 2 . and NH3 in this system changed over time. the following will most likely occur? (B) The temperature of the system decreased. -10- . Which of the following was true for the system 36. H2 gas and N2 gas were placed in a rigid vessel and allowed to reach equilibrium in the presence of a catalyst according to the following equation. H 2 and N 2 was zero. Questions 35-36 refer to the experiment described below. GO ON TO THE NEXT PAGE. molecules. equal to the rate of disappearance of H 2 (D) The amount of N2 will increase. (A) The value of the equilibrium constant will (C) The number of effective collisions between increase. 3 H2(g) + N2(g) Æ̈ 2 NH3(g) ΔH∞ = -92 kJ/molrxn The diagram below shows how the concentrations of H 2 . What is the percentage yield of O2 if 12. (D) DH for the reaction is lowered. (C) 50% (A) I only (D) 33% (B) II only (E) 10% (C) I and II only (D) II and III only 42. The product is favored over the reactants at (A) 100% equilibrium. The reason for of 6. Fe3+(aq) + SCN -(aq) Æ̈ Fe(SCN)2+(aq) (E) DG for the reaction becomes more positive. -11- .37. From this information. is 240 at 25∞C. GO ON TO THE NEXT PAGE. Keq . the value of 2 KClO3(s) Æ 2 KCl(s) + 3 O2(g) the equilibrium constant. the color changes abruptly at the endpoint of the titration 39. (C) The rate of the reverse reaction is increased.0 M is closest to the abruptness of this color change is that (A) 10 mL (A) a large change in pH occurs near the (B) 20 mL endpoint of the titration (C) 30 mL (B) a buffer solution exists at the endpoint of the (D) 40 mL titration (E) 60 mL (C) phenolphthalein is a strong proton donor (D) the pH of water is very resistant to change (E) phenolphthalein is much more sensitive to the pH of a solution than most other indicators Unauthorized copying or reuse of any part of this page is illegal.0 M HCl to a concentration of only one drop of acid or base. When a strong acid is titrated with a strong base (E) I. correct deductions about 41. II. When heated. The reaction is endothermic. 38. (D) metallic oxalate + O2 (B) The number of effective collisions between (E) metallic oxide + CO2 reactant particles is increased. (B) 67% III. The volume of water that must be added in order and can be switched back and forth by the addition to dilute 40 mL of 9. For the reaction represented above. Which of the following statements best explains produce why an increase in temperature of 5-10 Celsius degrees can substantially increase the rate of a (A) metallic peroxide + CO chemical reaction? (B) metal + CO + O2 (C) metallic hydroxide + CO2 (A) The activation energy for the reaction is lowered. The reaction is quite rapid.3 g the reaction at 25∞C include which of the of KClO3 (molar mass 123 g) is decomposed to following? produce 3. metallic carbonates generally 40.2 g of O2 (molar mass 32 g) according I. and III using phenolphthalein as an indicator. to the equation above? II. is represented above.6 ¥ 10 -3 M (E) 4. At 298 K and 1 atm. Which of the following aqueous solutions has the lowest freezing point? (A) 0. (D) an intermediate This provides evidence that. -12- . (C) Ag+ O3(g).0 ¥ 10 -2 M 46.2 m CaCl2 (C) 0.0 ¥ 10 -4 M (C) 1.6 ¥ 10 -7 M (B) 4.010 M Pb(NO3)2 ? (A) 1. A 1 mol sample of zinc can reduce the greatest Step 1: NO(g) + O3(g) Æ NO2(g) + O2(g) number of moles of which of the following ions? Step 2: NO2(g) + O(g) Æ NO(g) + O2(g) (A) Al3+ (B) Pb2+ 47. which of those among Cl2 molecules the techniques below is the best procedure? (B) forces among Br2 molecules are weaker than (A) Rinse the buret one time with some of the the Br-Br bond titrant solution.2 m NH3 (E) 0. A reaction mechanism for the destruction of ozone.6 ¥ 10 -5. The value of Ksp for PbCl 2 is 1.6 ¥ 10 -3 M (D) 2. (D) Br-Br bond is stronger than the Cl-Cl bond (C) Rinse the buret two times: once with some of (E) Br-Br bond is weaker than the Cl-Cl bond the titrant solution. When a buret is rinsed before a titration. is the lowest concentration of Cl−(aq) that would (E) Rinse the buret two times: each time with be needed to begin precipitation of PbCl2(s) in distilled water. In the overall reaction. (D) Cl . 45. under these (E) a product conditions. the (A) forces among Br2 molecules are greater than 48.2 m NaCl (B) 0. What (D) Rinse the buret two times: each time with some of the titrant solution. whereas chlorine is a gas. GO ON TO THE NEXT PAGE. bromine is a liquid with a (C) a reactant high vapor pressure. (B) Rinse the buret one time with some of the (C) forces among Cl2 molecules are stronger titrant solution and then dry the buret in an than the Cl-Cl bond oven. (A) an inhibitor (B) a catalyst 44. NO(g) is best described as (E) N3. then once with distilled water.43.2 m Al(NO3)3 Unauthorized copying or reuse of any part of this page is illegal.2 m H2SO4 (D) 0. 0. (C) At 25°C. (D) At 25°C. Unauthorized copying or reuse of any part of this page is illegal. (E) At 25°C. Δ G° for the reaction is positive.3. which of the following (A) a Lewis acid-base reaction must be correct? (B) a Brønsted-Lowry acid-base reaction (C) an Arrhenius acid-base reaction (A) The reaction rate decreases as the (D) an oxidation-reduction reaction temperature is increased.3. Δ H° for the reaction is negative. At 25°C. The reaction represented above is best represented above has a value of 1. -13- . At 50°C. the classified as value of the equilibrium constant is less than 1. the equilibrium constant for the reaction 50. (E) a precipitation reaction (B) The reaction is thermodynamically favorable only at temperatures above 25°C. Based on this information. Sr 2+(aq) + F -(aq) Æ̈ SrF +(aq) Ni2+(aq) + 6 NH3(aq) Æ [Ni(NH3)6]2+(aq) 49. Δ S° for the reaction is positive. GO ON TO THE NEXT PAGE. . . . Zn2+(aq) + . . NO3-(aq) → .Æ Cu(s) E° = 0. . GO ON TO THE NEXT PAGE. . the coefficient for Zn(s) is (A) 2 (B) 4 (C) 6 (D) 10 (E) 14 Unauthorized copying or reuse of any part of this page is illegal. . . . When the equation above is balanced and all coefficients are reduced to lowest whole number terms.34 V - Cr (aq) + e Æ Cr (aq) 3+ 2+ E° = -0. . H+(aq) + . According to the half-reactions represented above. .41 V 51. Zn(s) + . NH4+(aq) + . Cu2 +(aq) + 2 e . which of the following occurs in aqueous solutions under standard conditions? (A) Cu2 +(aq) + Cr 3 +(aq) Æ Cu(s) + Cr 2 +(aq) (B) Cu2 +(aq) + 2 Cr 2 +(aq) Æ Cu(s) + 2 Cr 3 +(aq) (C) Cu(s) + 2 Cr 3 +(aq) Æ Cu2 +(aq) + 2 Cr 2 +(aq) (D) Cu(s) + Cr 3 +(aq) Æ Cu2 +(aq) + Cr 2 +(aq) (E) 2 Cu 2 +(aq) + Cr 3 +(aq) Æ 2 Cu(s) + Cr 2 +(aq) . -14- . H2O(l) 52. . A solution of methanol. NH3(g).8 M (A) -190 kJ/molrxn (B) 3. CH3OH . 58. GO ON TO THE NEXT PAGE.4 g of fluorine.270 kJ/molrxn (E) -1. -15- . (E) Cl2 (C) An external source of potential must have been supplied. A glowing 54. When a magnesium wire is dipped into a solution splint inserted into a bottle full of the gas is of lead(II) nitrate. At 25°C. ∞ for the reaction What is the molarity of the H2SO4 solution at what is the value of D H298 25°C? represented above? (A) 1.60 contains carbon with sp2 hybridization? (C) 0.4 g mL−1. The mole fraction of methanol from solution.1 M (D) 7. Which of the following (E) C2H4Cl2 represents the empirical formula of the compound? (A) SF2 (B) SF3 (C) SF4 (D) SF5 (E) SF6 Unauthorized copying or reuse of any part of this page is illegal. in water is (D) The magnesium wire will be the cathode of a Mg/Pb cell.80 55. If the standard molar heats of formation of solution of aqueous H2SO4 (molar mass ammonia. A sample of a compound contains 3. (D) Br2 (B) Mg(s) is less easily oxidized than Pb(s). Which of the following can be concluded (A) N2 from this observation? (B) NO2 (A) The standard reduction potential. and gaseous water.6 M (B) -290 kJ/molrxn (C) 5. for (C) O2 Pb2+(aq) is greater than that for Mg2+(aq). a black deposit forms on the extinguished. are -46 kJ/mol and -242 kJ/mol. which is collected by water displacement. A chemical supply company sells a concentrated 53. the density of the solution is 1. The gas could be wire. A reaction produces a colorless gas.1 M (C) -580 kJ/molrxn (E) 14 M (D) -1. respectively. 98 g mol−1) that is 50. prepared by mixing together 128 g of methanol (E) Pb(s) can spontaneously displace Mg2+(aq) and 108 g of water.40 (E) 0. 4 NH3(g) + 3 O2(g) Æ 2 N2(g) + 6 H2O(g) 56. E ∞ .50 (A) CH4 (D) 0.640 kJ/molrxn 57. in the solution is closest to (A) 0.21 g of sulfur (D) C2H2Cl2 and 11. percent H2SO4 by mass. Which of the molecules represented below (B) 0.20 (B) CH2Cl2 (C) C2H6 59. H2O(g). which of the following is closest to the molecules in a gas volume of one mole of Hg(l) at this temperature? (A) are in constant motion (A) 0.4 mL (D) have a real. Of the following.14 mL (C) have relatively small masses (C) 1.60. nonzero volume (D) 14 mL (E) move slower as temperature decreases (E) 28 mL Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. the best explanation for the fact 61. -16- .070 mL (B) are relatively far apart (B) 0. Given that the density of Hg(l) at 0°C is about that most gases are easily compressed is that the 14 g mL-1. Measurements that must be made to calculate the molar mass of the gas include all of the following EXCEPT (A) atmospheric pressure (B) temperature of the water (C) volume of gas in the gas-collection tube (D) initial and final mass of the gas cylinder (E) mass of the water in the apparatus Unauthorized copying or reuse of any part of this page is illegal. After all the gas sample has been collected. the water levels inside and outside the gas collection tube are made the same. 62. -17- . GO ON TO THE NEXT PAGE. A sample of an unknown gas from a cylinder is collected over water in the apparatus shown above. (aq) Æ̈ BaSO3(s) + 2 H2O(l) (C) 2 H +(aq) + SO3 2 -(aq) + Ba 2 +(aq) + 2 OH . GO ON TO THE NEXT PAGE.(aq) Æ̈ BaSO3(s) + 2 H2O(l) (D) H SO (aq) + Ba 2 +(aq) + 2 OH . -18- .(aq) Æ̈ 2 H2O(l) (B) H2SO3(aq) + Ba 2 +(aq) + 2 OH .(aq) Æ̈ Ba 2 +(aq) + SO 2 -(aq) + 2 H O(l) 2 3 3 2 (E) H2SO3(aq) + Ba(OH)2(aq) Æ̈ BaSO3(s) + 2 H2O(l) Unauthorized copying or reuse of any part of this page is illegal. Addition of sulfurous acid (a weak acid) to barium hydroxide (a strong base) results in the formation of a precipitate.63. The net ionic equation for this reaction is (A) 2 H +(aq) + 2 OH . 0 kJ/molrxn (A) 2 2 2 2 64. what is the enthalpy change for the sublimation of iodine. GO ON TO THE NEXT PAGE. -19- .1 1 65. Which of the following graphs correctly shows H (g) + I (s) Æ HI(g) ΔH = 26 kJ/molrxn 2 2 2 2 the relationship between potential energy and internuclear separation for two hydrogen atoms? 1 1 H (g) + I (g) Æ HI(g) ΔH = -5. Based on the information above. represented below? I2(s) → I2(g) (B) (A) 15 kJ/molrxn (B) 21 kJ/molrxn (C) 31 kJ/molrxn (D) 42 kJ/molrxn (E) 62 kJ/molrxn (C) (D) (E) Unauthorized copying or reuse of any part of this page is illegal. Which of the following compounds is LEAST 68. Hg 22+(aq). -20- .0 (E) 12.68 M (D) 8. Mn2+(aq).0 (D) 0.10 M (B) 4. What is the molarity of I -(aq) in a solution 67. Based on 1. Which of the following could be the identity of the anion in the solution? (A) Cl . The graph above shows the titration curve that that contains 34 g of SrI2 (molar mass 341 g) in resulted when a sample of 0. the student observes that no precipitates form in the solution. Cu2+(aq).0 L of the solution? the graph.(aq) (B) CO32-(aq) (C) CrO42-(aq) (D) NO3-(aq) (E) SO42-(aq) 70.66. When a student prepares an aqueous solution containing the five cations Ag+(aq). (A) PCl 5 By what factor does the rate of the reaction (B) PBr3 change when the concentrations of both NO2 and (C) NF3 Cl2 are doubled? (D) NI 5 (A) 2 (E) SbF5 (B) 3 (C) 4 (D) 6 (E) 8 69.0 (E) 0.0 Unauthorized copying or reuse of any part of this page is illegal.20 M (C) 6. GO ON TO THE NEXT PAGE. The rate law for the reaction of nitrogen dioxide likely to exist? and chlorine is found to be rate = k [NO2]2[Cl2].1 M monoprotic acid was titrated with a solution of NaOH.068 M (A) 3. and Ba2+(aq).0 (C) 0. the pKa of the acid is closest to (A) 0.034 M (B) 0. a 2 S(s) + 3 O2(g) Æ̈ 2 SO3(g) K3 = ? serious environmental problem. what (E) NH4Cl is the value of the equilibrium constant. An example of such a gas is (A) 1 ¥ 10130 (A) N2 (B) 3 ¥ 1080 (B) O2 (C) 1 ¥ 1065 (C) H2O (D) 2 ¥ 1040 (D) NO2 (E) 7 ¥ 1024 (E) CH4 Unauthorized copying or reuse of any part of this page is illegal. Which of the following compounds contains both 2 S(s) + 2 O2(g) Æ̈ 2 SO2(g) K1 = 2 ¥ 10105 ionic and covalent bonds? (A) SO3 2 SO2(g) + O2(g) Æ̈ 2 SO3(g) K2 = 7 ¥ 1024 (B) C2H5OH (C) MgF2 73.71. for the following reaction? 72. Some pollutant gases in the atmosphere act as contributors to the formation of acid rain. -21- . GO ON TO THE NEXT PAGE. Given the value of the equilibrium constants K1 (D) H2S and K2 for the reactions represented above. K3 . YOU MAY CHECK YOUR WORK ON THIS SECTION. DO NOT GO ON TO SECTION II UNTIL YOU ARE TOLD TO DO SO. A 0.10 M solution of which of the following salts has polar covalent bonds? is most basic? (A) N2 (A) LiNO3 (B) H2O2 (B) Na2SO4 (C) H2O (C) CaCl2 (D) CCl4 (D) Al(NO3)3 (E) CH2Cl2 (E) K2CO3 END OF SECTION I IF YOU FINISH BEFORE TIME IS CALLED. • PLACED YOUR AP NUMBER LABEL ON YOUR ANSWER SHEET • WRITTEN AND GRIDDED YOUR AP NUMBER CORRECTLY ON YOUR ANSWER SHEET • TAKEN THE AP EXAM LABEL FROM THE FRONT OF THIS BOOKLET AND PLACED IT ON YOUR ANSWER SHEET Unauthorized copying or reuse of any part of this page is illegal. MAKE SURE YOU HAVE DONE THE FOLLOWING. -22- .74. Which of the following molecules is nonpolar but 75. .GO ON TO THE NEXT PAGE. It includes cover material and other administrative instructions to help familiarize students with the mechanics of the exam. (Note that future exams may differ in look from the following content. B Section II: Free-Response Questions This is the free-response section of the 2012 AP exam.) . Cross out any errors you make. you may go back to Part A. Question 5 15% Question 6 15% Form I Form Code 4EBP2-S2 Minimum 20% post-consumer waste 25 . At a Glance Total Time 1 hour. you may proceed freely from one Number of Questions question to the next within each part. Manage your time carefully. If you finish Part B before time is called. Pages containing a Question 1 20% periodic table. ® AP Chemistry Exam SECTION II: Free Response 2012 DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. However. Question 3 20% The proctor will announce the times for Part A and Part B. 35 minutes Number of Questions 6 Percent of Total Score 50% Writing Instrument Either pencil or pen with black or dark blue ink Part A Number of Questions 3 Time 55 minutes Electronic Device Instructions Calculator allowed Percent of Section II Score The questions for Part A and Part B are printed in this booklet. but you Question 4 10% may NOT use a calculator. Do not spend too much time on any one Percent of Section II Score question. erased or crossed-out work will None allowed not be scored. but you must write your answers in the areas designated for each response. 3 You may use the pages that the questions are printed on to organize your answers or for Time scratch work. reduction potentials. and lists containing equations and constants are also Question 2 20% printed in this booklet. 40 minutes Electronic Device Write clearly and legibly. you may not begin working Part B on Part B until the proctor tells you to do so. GO ON TO THE NEXT PAGE.INFORMATION IN THE TABLE BELOW AND IN THE TABLES ON PAGES 3-5 MAY BE USEFUL IN ANSWERING THE QUESTIONS IN THIS SECTION OF THE EXAMINATION. -2. . 14 . Æ - F2 ( g) + 2 e 2F 2. Æ Fe 3+ +e Fe 2+ 0. Æ 2 H 2 O(l ) 1. Æ K +e + K(s) – 2.05 -3.37 .13 . Æ 2 I. Æ Au 3+ + 3e Au(s) 1.79 .77 I 2 (s) + 2 e . Æ Ag + e+ Ag(s) 0. Æ Cu(s) 0.15 S(s) + 2 H + + 2 e .92 Hg2+ + 2 e .23 - Br2 (l ) + 2 e Æ 2 Br .92 . Æ Cr 3+ +e Cr 2+ – 0. Æ Co 2+ + 2e Co(s) – 0. Æ Be 2+ + 2e Be(s) – 1. Æ Ni 2+ + 2e Ni(s) – 0. – 0. Æ Sn 2+ + 2e Sn(s) – 0. Æ Cu 2+ +e Cu+ 0. 0.71 . . Æ Cu 2+ + 2e Cu(s) 0.18 .28 .50 - Cl2 (g ) + 2 e Æ 2 Cl .85 . Æ Hg(l ) 0.92 .14 . Æ Sn 2+ 0. Æ Pb 2+ + 2e Pb(s) – 0.53 Cu+ + e .52 .92 . Æ Hg22+ 0. Æ 2+ Co +e Co 1. Æ Cr 3+ + 3e Cr(s) – 0. Æ Hg2 2+ + 2e 2 Hg(l ) 0. Æ Na + e + Na(s) – 2.25 .89 .76 - 2 H 2 O(l ) + 2 e Æ H 2 ( g ) + 2 OH . Æ Mn(s) – 1.87 3+ .80 . Æ Ba 2+ + 2e Ba(s) – 2.36 O2 (g) + 4 H + + 4 e .74 .90 . 1. Æ + Li + e Li(s) – 3. GO ON TO THE NEXT PAGE.40 . Æ Ca 2+ + 2e Ca(s) – 2.87 . Æ Sr 2+ + 2e Sr(s) – 2.00 . Æ Rb + e + Rb(s) – 2. Æ Al 3+ + 3e Al(s) – 1.82 .07 2 Hg2+ + 2 e .83 Mn 2+ + 2 e .15 Sn 4+ + 2 e . Æ Fe(s) – 0.44 .70 . Æ Zn 2+ + 2e Zn(s) – 0. Æ Cs + e + Cs(s) – 2. Æ Mg 2+ + 2e Mg(s) – 2.STANDARD REDUCTION POTENTIALS IN AQUEOUS SOLUTION AT 25∞C Half-reaction E ∞(V) .41 Fe 2+ + 2 e .34 . Æ 2H + 2e + H2 (g) 0. Æ H 2S(g ) 0. 1.66 . Æ Cd 2+ + 2e Cd(s) – 0. 022 ¥ 1023 mol -1 Kb = [B] Electron charge. pOH = . h = 6.5 kJ mol -1 pH = . R = 8.602 ¥ 10 -19 coulomb K w = [OH ][H + ] = 1.31 J mol -1 K -1 1 - 1 = kt = 0. ADVANCED PLACEMENT CHEMISTRY EQUATIONS AND CONSTANTS ATOMIC STRUCTURE E = energy u = velocity E = hv c = lv v = frequency n = principal quantum number h l = wavelength m = mass l= p = mu mu p = momentum -2.log[OH .moles reactant gas S = standard entropy H = standard enthalpy THERMOCHEMISTRY/KINETICS G = standard free energy DS = S products - S reactants E = standard reduction potential DH =  DHf products - DH f reactants T = temperature n = moles DG =  DGf products - DGf reactants m = mass q = heat DG = DH .31 volt coulomb mol -1 K -1 GO ON TO THE NEXT PAGE.Ea 1 + ln A = 8.303 RT log Q A = frequency factor q = mcDT DH Faraday's constant.0 ¥ 108 m s -1 EQUILIBRIUM Planck’s constant.] Boltzmann’s constant.log K a .178 ¥ 10 -18 En = joule n2 Speed of light. -4- .0821 L atm mol -1 K -1 [A] t [A]0 = 62.log [H + ].][HB+ ] Avogadro’s number = 6.T D S c = specific heat capacity = .RT ln K = -2.38 ¥ 10 -23 J K -1 Ka = [HA] [OH .4 L torr mol -1 K -1 ln k = R T() .log K b K c (molar concentrations) Dn K p = K c ( RT ) . where D n = moles product gas .0 ¥ 10 -14 @ 25 C - = K a ¥ Kb 1 electron volt per atom = 96. c = 3.63 ¥ 10 -34 J s [H + ][A . k = 1. Ᏺ = 96.] 14 = pH + pOH Equilibrium Constants [A . e = -1.500 coulombs per mole Cp = DT of electrons ln [A ] t . pK b = .kt Gas constant.303 RT log K Cp = molar heat capacity at constant pressure = -n Ᏺ E Ea = activation energy k = rate constant DG = DG + RT ln Q = DG + 2.ln [A]0 = .] K a (weak acid) pH = pK a + log [HA] K b (weak base) [HB+ ] K w (water) pOH = pK b + log [B] K p (gas pressure) pK a = . GASES, LIQUIDS, AND SOLUTIONS PV = nRT P = pressure Ê V = volume n aˆ 2 ÁË P + 2 ˜¯ (V - nb) = nRT T = temperature V n = number of moles moles A PA = Ptotal ¥ X A , where X A = D = density total moles Ptotal = PA + PB + PC + ... m = mass m u = velocity n= M K = C + 273 PV PV urms = root-mean-square speed 1 1 = 2 2 KE = kinetic energy T1 T2 m r = rate of effusion D= M = molar mass V 3kT 3RT p = osmotic pressure urms = = m M i = van't Hoff factor 1 2 = KE per molecule = mu Kf molal freezing-point depression constant 2 3 Kb = molal boiling-point elevation constant KE per mole = RT 2 A = absorbance r1 M2 a = molar absorptivity = r2 M1 b = path length molarity, M = moles solute per liter solution c = concentration molality = moles solute per kilogram solvent Q = reaction quotient DT f = iK f ¥ molality I = current (amperes) DTb = iK b ¥ molality q = charge (coulombs) p = iMRT t = time (seconds) A = abc E = standard reduction potential K = equilibrium constant OXIDATION-REDUCTION; ELECTROCHEMISTRY Gas constant, R = 8.31 J mol -1 K -1 = 0.0821 L atm mol -1 K -1 [C] c [D] d = 62.4 L torr mol -1 K -1 Q= a b , where a A + b B Æ c C + d D [A] [B] = 8.31 volt coulomb mol -1 K -1 I = q Boltzmann's constant, k = 1.38 ¥ 10 -23 J K -1 t K f for H2 O = 1.86 K kg mol -1 RT 0.0592 Ecell = Ecell - ln Q = Ecell - log Q @ 25 C K b for H2 O = 0.512 K kg mol -1 nᏲ n 1 atm = 760 mm Hg nE log K = = 760 torr 0.0592 STP = 0.00 C and 1.0 atm Faraday's constant, Ᏺ = 96,500 coulombs per mole of electrons GO ON TO THE NEXT PAGE. -5- CHEMISTRY Section II (Total time—95 minutes) Part A Time— 55 minutes YOU MAY USE YOUR CALCULATOR FOR PART A. CLEARLY SHOW THE METHOD USED AND THE STEPS INVOLVED IN ARRIVING AT YOUR ANSWERS. It is to your advantage to do this, since you may obtain partial credit if you do and you will receive little or no credit if you do not. Attention should be paid to significant figures. Be sure to write all your answers to the questions on the lined pages following each question in this booklet. Answer Questions 1, 2, and 3. The Section II score weighting for each question is 20 percent. CH3NH2(aq) + H2O(l) Æ̈ CH3NH3+(aq) + OH−(aq) Kb = 4.4 × 10 − 4 1. Methylamine, CH3NH2 , is a weak base that reacts with water according to the equation above. A student obtains a 50.0 mL sample of a methylamine solution and determines the pH of the solution to be 11.77. (a) Write the expression for the equilibrium constant, Kb , for methylamine. (b) Calculate the molar concentration of OH - in the 50.0 mL sample of the methylamine solution. (c) Calculate the initial molar concentration of CH3NH2(aq) in the solution before it reacted with water and equilibrium was established. The 50.0 mL sample of the methylamine solution is titrated with an HCl solution of unknown concentration. The equivalence point of the titration is reached after a volume of 36.0 mL of the HCl solution is added. The pH of the solution at the equivalence point is 5.98. (d) Write the net-ionic equation that represents the reaction that takes place during the titration. (e) Calculate the concentration of the HCl solution used to titrate the methylamine. (f) Using the axes provided, sketch the titration curve that results from the titration described above. On the graph, clearly label the equivalence point of the titration. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -6- Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -7- ADDITIONAL PAGE FOR ANSWERING QUESTION 1 GO ON TO THE NEXT PAGE. -8- . -9- .ADDITIONAL PAGE FOR ANSWERING QUESTION 1 GO ON TO THE NEXT PAGE. as represented by the net ionic equation above.0360 g sample of pure magnesium and a solution of 2. (a) Calculate the number of moles of magnesium in the 0. A student performs an experiment to determine the volume of hydrogen gas produced when a given mass of magnesium reacts with excess HCl(aq) . (e) The laboratory procedure specified that the concentration of the HCl solution be 2.0 mL graduated cylinder Distilled water 250 mL beakers Balance 50. The student begins with a 0.0 M HCl(aq) using 12. -10- .3 M HCl solution and materials selected from the list below. that the H2(g) produced in the reaction would have if it were dry. Describe the steps for safely preparing 50. Mg(s) + 2 H+(aq) → Mg2+(aq) + H2(g) 2.0 M HCl(aq) . the hydrogen gas produced is collected by water displacement at 23. (d) Calculate the volume. (b) Calculate the number of moles of HCl(aq) needed to react completely with the sample of magnesium.0360 g sample.3 M HCl solution was available. (c) Given that the equilibrium vapor pressure of water is 21 torr at 23.0 mL of 2. calculate the pressure that the H2(g) produced in the reaction would have if it were dry. 10.0°C. Show any necessary calculation(s).0°C. The pressure of the gas in the collection tube is measured to be 749 torr. As the magnesium reacts.00 mL volumetric flask Dropper Unauthorized copying or reuse of any part of this page is illegal.0 M. GO ON TO THE NEXT PAGE. in liters measured at the conditions in the laboratory. but only 12. -11- .ADDITIONAL PAGE FOR ANSWERING QUESTION 2 GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 2 GO ON TO THE NEXT PAGE. -12- . -13- .ADDITIONAL PAGE FOR ANSWERING QUESTION 2 GO ON TO THE NEXT PAGE. what will be the pressure. of the solid that remains after the dehydration reaction is complete. of water vapor in the cylinder at equilibrium at 298 K.49 g sample of pure CaSO4⋅ 2H2O(s) is heated several times until the mass is constant. in atm. The air above the solid is at 1.59 (b) Given that the value of ΔH ° for the reaction at 298 K is +105 kJ/molrxn .4 at 298 K. CaSO4(s). Kp . -14- . Substance DG f at 298 K (kJ/mol) CaSO4⋅ 2H2O(s) −1795. (a) Using the data in the table below. Kp .00 atm and is initially dry (partial pressure of H2O(g) = 0 atm). CaSO4⋅ 2H2O(s) Æ̈ CaSO4(s) + 2 H2O(g) 3. as shown by the reaction represented above. calculate the value of ΔG °. (f) A 2. calculate the value of ΔS ° for the reaction at 298 K. in atm. A sample of CaSO4⋅ 2H2O(s) is placed in a cylinder with a movable piston as shown in the diagram below. is 6. Include units with your answer. (e) If the volume of the system is reduced to one-half of its original volume and the system is allowed to reestablish equilibrium at 298 K. of the water vapor at the new volume? Justify your answer. In the laboratory. GO ON TO THE NEXT PAGE. The hydrate CaSO4⋅ 2H2O(s) can be heated to form the anhydrous salt. in kJ/molrxn . for the reaction at 298 K.70 CaSO4(s) −1320.4 × 10. (d) Given that the equilibrium constant. the hydrate CaSO4⋅ 2H2O(s) can be heated in a crucible to completely drive off the water of hydration to form the anhydrous salt. for the reaction.30 H2O(g) −228. determine the partial pressure. Calculate the mass. CaSO4(s). in grams. (c) Write the expression for the equilibrium constant. Unauthorized copying or reuse of any part of this page is illegal. ADDITIONAL PAGE FOR ANSWERING QUESTION 3 GO ON TO THE NEXT PAGE. -15- . ADDITIONAL PAGE FOR ANSWERING QUESTION 3 GO ON TO THE NEXT PAGE. -16- . Do not turn to the other part of the test until you are told to do so. -17- . ADDITIONAL PAGE FOR ANSWERING QUESTION 3 STOP If you finish before time is called. you may check your work on this part only. but only equations that are written in the answer boxes provided will be scored. Answer Question 4 below. in part (i) write a balanced equation for the reaction and in part (ii) answer the question about the reaction. coefficients should be in terms of lowest whole numbers. In part (i). GO ON TO THE NEXT PAGE. or greater than 7? Explain. -18- . Assume that solutions are aqueous unless otherwise indicated. (i) Balanced equation: (ii) If the ethanoic acid is titrated with the lithium hydroxide. Omit formulas for any ions or molecules that are unchanged by the reaction. is the pH at the equivalence point equal to 7. (a) Solutions of ethanoic (acetic) acid and lithium hydroxide are combined. Represent substances in solutions as ions if the substances are extensively ionized. ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ Unauthorized copying or reuse of any part of this page is illegal. 4. For each of the following three reactions. The Section II score weighting for this question is 10 percent. less than 7. You may use the empty space at the bottom of the next page for scratch work. B B B B B B B B B B B B B B CHEMISTRY Part B Time— 40 minutes NO CALCULATORS MAY BE USED FOR PART B. which reactant. Unauthorized copying or reuse of any part of this page is illegal. (i) Balanced equation: (ii) If 5 mol of silver(I) nitrate and 3 mol of sodium phosphate react as completely as possible. B B B B B B B B B B B B B B (b) Solutions of iron(III) chloride and tin(II) chloride are combined. (i) Balanced equation: (ii) Identify the species that is reduced in the reaction. -19- . ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ YOU MAY USE THE SPACE BELOW FOR SCRATCH WORK. is present in excess? Justify your answer. if any. GO ON TO THE NEXT PAGE. BUT ONLY EQUATIONS THAT ARE WRITTEN IN THE ANSWER BOXES PROVIDED WILL BE SCORED. forming a precipitate. ______________________________________________________________________________________ ______________________________________________________________________________________ (c) Solutions of silver(I) nitrate and sodium phosphate are combined. The Section II score weighting for these questions is 15 percent each. diffuse responses. Explanations should be clear and well organized. and the resulting data were plotted in the graph below. GO ON TO THE NEXT PAGE. A proposed mechanism for the reaction. 2 H2O2(aq) → 2 H2O(l) + O2(g) 5. Examples and equations may be included in your responses where appropriate. B B B B B B B B B B B B B B Answer Question 5 and Question 6. Unauthorized copying or reuse of any part of this page is illegal. is represented by the three equations below. which involves the free radicals HO i and HOO i . Your responses to these questions will be scored on the basis of the accuracy and relevance of the information cited. The decomposition of hydrogen peroxide to form water and oxygen gas is represented by the equation above. (b) The rate of the decomposition reaction was studied in an experiment. Specific answers are preferable to broad. H 2 O2 Æ 2 HO i (slow) H 2O2 + HO i Æ H 2 O + HOO i (fast) HOO i + HO i Æ H 2 O + O2 (fast) (a) Write the rate law consistent with the proposed mechanism above. -20- . Half-Reaction Standard Reduction Potential. GO ON TO THE NEXT PAGE. needed for the concentration of H2O2 to change from (i) 1. Keq ΔG° ΔH° Ea (ii) For any quantity that you circled above. E °.80 M to 0. Explain why.50 M to 0. E ° H2O2 + 2 e− → 2 OH− 0. less than 0. (i) Draw a circle around each of the quantities below that has a different value for the catalyzed reaction than for the uncatalyzed reaction.88 V O2 + 2 H2O + 2 e− → H2O2 + 2 OH− −0. Justify your answer. for the cell. An electrochemical cell based on the decomposition of H2O2 can be constructed based on the half-reactions in the table below. indicate whether its value is greater or less for the catalyzed reaction than for the uncatalyzed reaction. (e) Indicate whether ΔG° for the decomposition reaction is greater than 0. in hours. determine the time. (f) The decomposition of H2O2(aq) is slow at 298 K. but a suitable catalyst greatly increases the rate of the decomposition reaction.75 M (ii) 0. or equal to 0. B B B B B B B B B B B B B B Using the graph.15 V (d) Calculate the value of the standard cell potential. Explain. Unauthorized copying or reuse of any part of this page is illegal. -21- .40 M (c) The experimental data are consistent with the proposed mechanism. -22- .B B B B B B B B B B B B B B ADDITIONAL PAGE FOR ANSWERING QUESTION 5 GO ON TO THE NEXT PAGE. B B B B B B B B B B B B B B ADDITIONAL PAGE FOR ANSWERING QUESTION 5 GO ON TO THE NEXT PAGE. -23- . The following complete Lewis electron-dot diagrams may be useful in answering parts of this question. Explain. HC3H5O2 . have the same length. Explain. HCO2−. (e) Explain the following observations about the two carbon-oxygen bonds in the methanoate (formate) anion. GO ON TO THE NEXT PAGE. -24- . (c) Indicate the hybridization of the carbon atom in each of the following: (i) Methanol (ii) Methanoic (formic) acid (d) Draw the complete Lewis electron-dot diagram for a molecule of propanoic acid. a complete answer must include a discussion of both substances. methanol is a liquid whereas propane is a gas. HCO2−. In each explanation where a comparison is to be made. (i) The two carbon-oxygen bonds in the methanoate (formate) anion. HCO2−. pentane is a liquid whereas propane is a gas. B B B B B B B B B B B B B B 6. (ii) The length of the carbon-oxygen bonds in the methanoate (formate) anion. Unauthorized copying or reuse of any part of this page is illegal. is intermediate between the length of the carbon-oxygen bond in methanol and the length of the carbon-oxygen bond in methanal . You may draw a Lewis electron-dot diagram (or diagrams) of the methanoate ion as part of your explanations. (a) At 1 atm and 298 K. Answer the following questions in terms of principles of chemical bonding and intermolecular forces. (b) At 1 atm and 298 K. -25- .B B B B B B B B B B B B B B ADDITIONAL PAGE FOR ANSWERING QUESTION 6 GO ON TO THE NEXT PAGE. -26- .B B B B B B B B B B B B B B ADDITIONAL PAGE FOR ANSWERING QUESTION 6 GO ON TO THE NEXT PAGE. -27- .B B B B B B B B B B B B B B ADDITIONAL PAGE FOR ANSWERING QUESTION 6 GO ON TO THE NEXT PAGE. -28- . BUT YOU MAY NOT USE A CALCULATOR. YOU MAY RETURN TO PART A OF SECTION II IF YOU WISH. • CHECK TO SEE THAT YOUR AP NUMBER LABEL APPEARS IN THE BOX(ES) ON THE COVER(S). STOP END OF EXAM IF YOU FINISH PART B OF SECTION II BEFORE TIME IS CALLED. THE FOLLOWING INSTRUCTIONS APPLY TO THE COVERS OF THE SECTION II BOOKLET. • MAKE SURE YOU HAVE USED THE SAME SET OF AP NUMBER LABELS ON ALL AP EXAMS YOU HAVE TAKEN THIS YEAR. • MAKE SURE YOU HAVE COMPLETED THE IDENTIFICATION INFORMATION AS REQUESTED ON THE FRONT AND BACK COVERS OF THE SECTION II BOOKLET. .GO ON TO THE NEXT PAGE. B Multiple-Choice Answer Key The following contains the answers to the multiple-choice questions in this exam. Answer Key for AP Chemistry Practice Exam, Section I Multiple-Choice Questions 38 B Question # Key 39 B 1 B 40 B 2 B 41 B 3 C 42 A 4 D 43 C 5 B 44 A 6 B 45 E 7 A 46 E 8 B 47 B 9 A 48 D 10 C 49 E 11 D 50 A 12 A 51 B 13 A 52 B 14 C 53 D 15 D 54 A 16 A 55 D 17 E 56 D 18 B 57 A 19 D 58 D 20 C 59 E 21 D 60 B 22 D 61 D 23 B 62 E 24 B 63 B 25 B 64 E 26 A 65 D 27 C 66 D 28 B 67 B 29 D 68 E 30 A 69 D 31 C 70 D 32 C 71 E 33 A 72 D 34 A 73 A 35 D 74 D 36 D 75 E 37 E B Free-Response Scoring Guidelines The following contains the scoring guidelines for the free-response questions in this exam. 23 [OH−] = 10−2.085 M does not earn the second point. pH = 11.com (for AP professionals) and www. [CH3 NH 2 ] One point is earned for the correct −4 (5. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 1 → CH NH +(aq) + OH−(aq) CH3NH2(aq) + H2O(l) ← Kb = 4.0 × 10 −14 [OH−] = = = 5. [CH3 NH3+ ][OH − ] Kb = One point is earned for [CH3NH3+] = [OH−].77.4 × 10 = ( x − 5.com/apstudents (for students and parents). for methylamine. OR pOH = 14 − pH = 2. Kb = [CH3 NH 2 ] (b) Calculate the molar concentration of OH− in the 50.9 × 10−3 ) initial molar concentration.collegeboard.0 mL sample of the methylamine solution. Visit apcentral.77 [H+] = 10−11.9 × 10−3 (c) Calculate the initial molar concentration of CH3NH2(aq) in the solution before it reacted with water and equilibrium was established. © 2012 The College Board. All rights reserved.23 = 5. 4.4 × 10 − 4 3 3 Methylamine.0 mL sample of a methylamine solution and determines the pH of the solution to be 11.7 × 10−12 Kw 1.77 = 1. CH3NH2 . is a weak base that reacts with water according to the equation above. (a) Write the expression for the equilibrium constant.9 × 10−3 ) Note: An approximated molar concentration x = 0.collegeboard. 1 . [CH3 NH3+ ][OH − ] One point is earned for the correct expression. Kb .9 × 10−3 )(5. A student obtains a 50.9 × 10−3 [H + ] 1.7 × 10 −12 One point is earned for correct [OH−]. The equivalence point of the titration is reached after a volume of 36.0 mL sample of the methylamine solution is titrated with an HCl solution of unknown concentration. 0.collegeboard.0 mL = 0. Visit apcentral.collegeboard.com/apstudents (for students and parents). CH3NH2 + H3O+ → CH3NH3+ + H2O OR One point is earned for a correct equation.00425 mol HCl 1000. 2 .000 L © 2012 The College Board.0 mL 1.0 mL of the HCl solution is added. All rights reserved. × = 0.com (for AP professionals) and www. The pH of the solution at the equivalence point is 5.00425 mol CH3NH2 1000.12 M 36.085 mol One point is earned for equal moles of acid and × 50. mL base. mL One point is earned for the correct concentration. 0.98. (d) Write the net-ionic equation that represents the reaction that takes place during the titration. CH3NH2 + H+ → CH3NH3+ (e) Calculate the concentration of the HCl solution used to titrate the methylamine. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 1 (continued) The 50. One point is earned for labeling the equivalence point at V = ~36. 3 . AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 1 (continued) (f) Using the axes provided.collegeboard. sketch the titration curve that results from the titration described above.com (for AP professionals) and www. On the graph.0 mL HCl and a pH of ~5. One point is earned for a curve starting at a pH between 11 and 12. One point is earned for general shape of the curve for a weak acid/strong base titration. Visit apcentral. All rights reserved.collegeboard. clearly label the equivalence point of the titration.98 .com/apstudents (for students and parents). © 2012 The College Board. 1 mol Mg Note: For errors in significant figures or mathematics. that the H2(g) produced in the reaction would have if it were dry. For the entire question.958 atm volume.00296 mol HCl correct number of moles of HCl. × 0. calculate the pressure that the H2(g) produced in the reaction would have if it were dry.00148 mol Mg × = 0. 1 mol Mg As the magnesium reacts.0360 g sample.com/apstudents (for students and parents). All rights reserved.00148 mol Mg 24. (a) Calculate the number of moles of magnesium in the 0.00148 mol H 2 )(0. (0. the hydrogen gas produced is collected by water displacement at 23.collegeboard. One point is earned for the correct number of moles of Mg. (c) Given that the equilibrium vapor pressure of water is 21 torr at 23. Visit apcentral. P = 749 torr − 21 torr = 728 torr One point is earned for the correct pressure.0 M HCl(aq) . 4 .30 g Mg there is a 1 point deduction.0375 L © 2012 The College Board. = 0. nRT One point is earned for PV = nRT  V = P the correct moles of H2(g).0821 L atm mol −1 K −1 )(296 K) One point is earned for the correct V = temperature substitution and calculated 0. (d) Calculate the volume. in liters measured at the conditions in the laboratory. only 1 point total can be deducted for each type of error. (b) Calculate the number of moles of HCl(aq) needed to react completely with the sample of magnesium. as represented by the net ionic equation above. 1 atm One point is earned for agreement 728 torr × = 0.0360 g = 0.0°C. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 2 Mg(s) + 2 H+(aq) → Mg2+(aq) + H2(g) A student performs an experiment to determine the volume of hydrogen gas produced when a given mass of magnesium reacts with excess HCl(aq) .0360 g sample of pure magnesium and a solution of 2.collegeboard. The barometric pressure in the lab is measured to be 749 torr.com (for AP professionals) and www. 2 mol H + One point is earned for the 0.0°C. The student begins with a 0.958 atm 760 torr of units of P (from part(c)) and R. 3 M HCl solution and materials selected from the list below.00 mL volumetric flask Dropper 2.00 mL mark with cylinder.1 mL the correct volume of 12.0 mL of 2.0 mol HCl × 50.0 mL graduated cylinder Distilled water 250 mL beakers Balance 50. 12.com (for AP professionals) and www.com/apstudents (for students and parents). mL × 0. distilled water. but only 12. Use the graduated cylinder to measure 8.3 mol HCl One point is earned for adding acid to Pour some distilled water into the volumetric flask so it is water in the dilution process.3 M HCl.3 M HCl and pour it into the volumetric flask.10 mol HCl 1000.collegeboard.0 M. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 2 (continued) (e) The laboratory procedure specified that the concentration of the HCl solution be 2. © 2012 The College Board.0 mL = 0. Describe the steps for safely preparing 50. Swirl the flask to mix. swirl. Carefully add more distilled water to the flask. and add the liquid to the volumetric flask.0 M HCl(aq) using 12.collegeboard.1 mL of 12. All rights reserved. about half full. 5 . One point is earned for filling Add a few mL of distilled water to the graduated the volumetric to the 50. Show any necessary calculation(s). mL One point is earned for calculating 1000.10 mol HCl = 8. using the dropper for the last few mL to fill the flask to the mark with distilled water. Visit apcentral. 10.3 M HCl solution was available. CaSO4(s).70 CaSO4(s) −1320.30 H2O(g) −228. and T. ΔG ° = ΔH ° − TΔS ° One point is earned for the correct substitution of ΔG °.collegeboard. = −1320.59 One point is earned ΔG ° = Σ ΔG f products − Σ ΔG f reactants for the mole factor for water.com (for AP professionals) and www. calculate the value of ΔG °.22) kJ mol−1 ΔS ° = = T 298 K One point is earned for the correct = 0. for the reaction at 298 K.22 kJ mol (b) Given that the value of ΔH ° for the reaction at 298 K is +105 kJ mol−1.com/apstudents (for students and parents).59) − (−1795. (a) Using the data in the table below.29 kJ K−1 mol−1 OR 290 J K−1 mol−1 answer with correct units. © 2012 The College Board. Visit apcentral.collegeboard. calculate the value of ΔS ° for the reaction at 298 K. as shown by the reaction represented above. ΔH °. All rights reserved. ΔH  − ΔG  (105 − 18. Substance ΔG f at 298 K (kJ mol−1) CaSO4⋅ 2H2O(s) −1795.70 kJ mol−1) One point is earned for answer −1 (units are optional) = 18. Include units with your answer. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 3 → CaSO (s) + 2 H O(g) CaSO4⋅ 2H2O(s) ← 4 2 The hydrate CaSO4⋅ 2H2O(s) can be heated to form the anhydrous salt. in kJ mol−1. 6 .30 + (2 × −228. Because the answer with justification.com/apstudents (for students and parents).025 atm. © 2012 The College Board. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 3 (continued) A sample of CaSO4⋅ 2H2O(s) is placed in a cylinder with a movable piston as shown in the diagram below. of the water vapor at the new volume? Justify your answer. (d) Given that the equilibrium constant. in atm. is 6. not volume. determine the partial pressure. The air above the solid is at 1.4 × 10− 4 at 298 K. pH2O = 6. in atm. (c) Write the expression for the equilibrium constant.00 atm and is initially dry (partial pressure of H2O(g) = 0 atm).4 × 10− 4 One point is earned for the correct partial pressure (units are not required). the vapor pressure of H2O remains 0. One point is earned for the correct expression (use Kp = ( pH2O )2 of partial pressure only).collegeboard.collegeboard. Kp . which in turn One point is earned for the correct is a function of temperature. The pH2O at equilibrium at the new volume will be 0. 7 . All rights reserved.4 × 10−4 = 0. Visit apcentral.025 atm in the new volume.025 atm (e) If the volume of the system is reduced to one-half of its original volume and the system is allowed to reestablish equilibrium at 298 K. what will be the pressure.com (for AP professionals) and www. Equilibrium vapor pressure is dependent on Kp . temperature is still 298 K. Kp . of water vapor in the cylinder at equilibrium at 298 K. Kp = ( pH2O )2  6. for the reaction. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 3 (continued) In the laboratory. 172.14 g mol−1 One point is earned for an 136.collegeboard.14 g CaSO 4 answer consistent with 2.com (for AP professionals) and www. molar mass of CaSO4(s) = 136. the hydrate CaSO4⋅ 2H2O(s) can be heated in a crucible to completely drive off the water of hydration to form the anhydrous salt. Calculate the mass. Visit apcentral.172 g mol−1 One point is earned for the (rounded) correct molar masses. CaSO4(s). in grams. of the solid that remains after the dehydration reaction is complete.172 g CaSO 4 ·2H 2 O © 2012 The College Board. All rights reserved.collegeboard.49 g CaSO4⋅ 2H2O × = 1. (f) A 2.97 g CaSO4 the molar masses. 8 .com/apstudents (for students and parents). molar mass of CaSO4⋅ 2H2O(s) = 172.49 g sample of pure CaSO4⋅ 2H2O(s) is heated several times until the mass is constant. (i) Balanced equation: One point is earned for the correct reactants. Visit apcentral. Fe3+ is reduced. HC2H3O2 is a weak acid and LiOH is a strong base. less than 7. (a) Solutions of ethanoic (acetic) acid and lithium hydroxide are combined. coefficients should be in terms of lowest whole numbers. 2 Fe3+ + Sn2+ → 2 Fe2+ + Sn4+ Two points are earned for the correct products. reaction. OR One point is earned for balancing 2 Fe3+ + 3 Sn2+ → 2 Fe + 3 Sn4+ the equation for both mass and charge. In part (i). is the pH at the equivalence point equal to 7. HC2H3O2 + OH− → C2H3O2− + H2O Two points are earned for the correct products. (i) Balanced equation: One point is earned for the correct reactants. Assume that solutions are aqueous unless otherwise indicated. or greater than 7? Explain.collegeboard.collegeboard. © 2012 The College Board. Omit formulas for any ions or molecules that are unchanged by the reaction. You may use the empty space at the bottom of the next page for scratch work. C H O − + H O ← → HC H O + OH−.com/apstudents (for students and parents). At the equivalence point. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 4 For each of the following three reactions. One point is earned for correct answer. 2 3 2 2 2 3 2 (b) Solutions of iron(III) chloride and tin(II) chloride are combined. One point is earned for balancing the equation for mass and charge. (ii) Identify the species that is reduced in the reaction. but only equations that are written in the answer boxes provided will be graded. (ii) If the ethanoic acid is titrated with the lithium hydroxide. All rights reserved. Represent substances in solutions as ions if the substances are extensively ionized. in part (i) write a balanced equation for the reaction and in part (ii) answer the question about the reaction. The pH will be greater than 7.com (for AP professionals) and www. 9 . the One point is earned for the C2H3O2− is the pH-determining species because of the correct answer with an explanation. (i) Balanced equation: Two points are earned for the correct reactants.com (for AP professionals) and www. is present in excess? Justify your answer.collegeboard. © 2012 The College Board. One point is earned for balancing the equation for both mass and charge.com/apstudents (for students and parents). so sodium phosphate is correct answer with reference to reactant present in excess. 3 Ag+ + PO43− → Ag3PO4 One point is earned for the correct product. All rights reserved. if any. Nine moles of Ag+ would be needed to react completely One point is earned for a with the three moles of PO43−. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 4 (continued) (c) Solutions of silver(I) nitrate and sodium phosphate are combined. which reactant. (ii) If 5 mol of silver(I) nitrate and 3 mol of sodium phosphate react as completely as possible. 10 .collegeboard. data. forming a precipitate. Visit apcentral. rate = k [H2O2] One point is earned for the correct rate law. (b) The rate of the decomposition reaction was studied in an experiment. which involves the free radicals HO· and HOO· . 11 . is represented by the three equations below.com/apstudents (for students and parents). © 2012 The College Board.collegeboard. Visit apcentral. All rights reserved.collegeboard. A proposed mechanism for the reaction. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 5 2 H2O2(aq) → 2 H2O(l) + O2(g) The decomposition of hydrogen peroxide to form water and oxygen gas is represented by the equation above. H 2O2 → 2 HO· (slow) H 2 O 2 + HO· → H 2 O + HOO· (fast) HOO· + HO· → H 2O + O2 (fast) (a) Write the rate law consistent with the proposed mechanism above.com (for AP professionals) and www. and the resulting data were plotted in the graph below. 88 V One point is earned for __________________________________________ the correct value of E °.66 = 0.collegeboard. All rights reserved.50 ± 0. indicating a first-order reaction.05 hour One point is earned for the correct time.80 M to 0.05 hour One point is earned for the correct time. 12 . 2 H2O2 → 2 H2O + O2 1. (ii) 0.15 V (d) Calculate the value of the standard cell potential.21 = 0. The rate law for the proposed mechanism has [H2O2] to the first power.51 ± 0. needed for the concentration of H2O2 to change from (i) 1.40 M Time = 1. (c) The experimental data are consistent with the proposed mechanism. Half-Reaction Standard Reduction Potential.71 − 0.15 V H2O2 + 2 e− → 2 OH− 0. for the cell.com/apstudents (for students and parents). E ° H2O2 + 2 e− → 2 OH− 0.50 M to 0. An electrochemical cell based on the decomposition of H2O2 can be constructed based on the half-reactions in the table below. indicating One point is earned for that the reaction is first order. in hours. The data show that the time remains constant when the concentration of the reactant decreases by one-half.collegeboard. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 5 (continued) Using the graph. E °.88 V O2 + 2 H2O + 2 e− → H2O2 + 2 OH− −0. H2O2 + 2 OH− → O2 + 2 H2O + 2 e− 0. Explain.17 − 0. a correct explanation. determine the time. Visit apcentral.com (for AP professionals) and www.75 M Time = 0.03 V © 2012 The College Board. (f) The decomposition of H2O2(aq) is slow at 298 K. Because E° is positive. ΔG° = −nFE°. A catalyst provides a new reaction One point is earned for a correct mechanism that requires a lower minimum required potential answer with reference to an altered energy for the reaction to occur.com/apstudents (for students and parents). Thus the activation energy is mechanism.collegeboard. the activation energy. lowered. indicate whether its value is greater or less for the catalyzed reaction than for the uncatalyzed reaction. is less for the catalyzed reaction than for the uncatalyzed reaction. Justify your answer. ΔG° is always negative. All rights reserved.collegeboard. One point is earned for the OR correct answer with justification. E° is positive. ΔG° is less than 0. (i) Draw a circle around each of the quantities below that has a different value for the catalyzed reaction than for the uncatalyzed reaction. For spontaneous reactions. ΔG° must be negative. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 5 (continued) (e) Indicate whether ΔG° for the decomposition reaction is greater than 0. © 2012 The College Board. (ii) For any quantity that you circled above.com (for AP professionals) and www. thus the reaction is spontaneous. less than 0. Keq ΔG° ΔH° Ea One point is earned for circling Ea Only Ea should be circled. 13 . but a suitable catalyst greatly increases the rate of the decomposition reaction. Explain why. and none of the other quantities. Note: reference to other circled quantities is ignored. Ea . or equal to 0. Visit apcentral. matter). methanol is a liquid whereas propane is a gas. a complete answer must include a discussion of both substances. Visit apcentral. (a) At 1 atm and 298 K. (b) At 1 atm and 298 K.collegeboard. All rights reserved. Explain. pentane is larger recognizing that pentane and than propane and has a more extensive electron cloud that can be propane both have only LDF’s. Methanol molecules One point is earned for recognizing that are polar and hydrogen bonds (as well as London forces) methanol has hydrogen-bonding IMF’s can form among them. 14 . © 2012 The College Board.collegeboard. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 6 Answer the following questions in terms of principles of chemical bonding and intermolecular forces. In each explanation where a comparison is to be made. thus methanol has the higher boiling point. Because hydrogen bonds are and propane has LDF’s. Propane molecules are nonpolar and only interact with one another via London dispersion forces. However. methanol has greater intermolecular attractions.com (for AP professionals) and www. and the only intermolecular forces One point is earned for in each are London dispersion forces. Thus it takes a higher that pentane has a larger electron temperature for pentane molecules to have enough kinetic energy cloud with greater IMF’s and (on average) to overcome their stronger intermolecular higher BP (reference to state of attractions. Explain. Both molecules are nonpolar.com/apstudents (for students and parents). stronger than London forces. intermolecular attractions. involved in a greater number of London interactions. leading to One point is earned for recognizing stronger intermolecular attractions overall. thus pentane has the higher boiling point. pentane is a liquid whereas propane is a gas. The following complete Lewis electron-dot diagrams may be useful in answering parts of this question. Thus it takes a higher One point is earned for recognizing that temperature for methanol molecules to have enough hydrogen-bonding results in a greater kinetic energy (on average) to overcome their stronger IMF causing methanol to be a liquid. The two identical carbon-oxygen bonds in the methanoate anion each have a bond order of 1. with one carbon- oxygen bond as a single bond and the other as a double bond (and the opposite One point is earned in the other structure). All rights reserved.com (for AP professionals) and www. (ii) The length of the carbon-oxygen bonds in the methanoate (formate) anion.5. H H (e) Explain the following observations about the two carbon-oxygen bonds in the methanoate (formate) anion. 15 . HCO2−. The carbon-oxygen bond in methanol One point is earned for the is a single bond. double bond. HC3H5O2 . double and are longer than double bonds. Resonance structures can be drawn for the methanoate anion. have the same length. One point is earned for the correct diagram H C C C O H .5 resonating bonds of the would have a bond length between that of a single bond and that of a respective molecules. (ii) Methanoic (formic) acid sp2 One point is earned for the correct hybridization. H H :O: . (all electron pairs must be included). HCO2−. and the carbon-oxygen bond in methanal is a correct explanation comparing double bond. Visit apcentral.. (i) The two carbon-oxygen bonds in the methanoate (formate) anion..com/apstudents (for students and parents).collegeboard. and a bond with a bond order of 1. same length. is intermediate between the length of the carbon-oxygen bond in methanol and the length of the carbon-oxygen bond in methanal. resulting in two bonds with the explanation. HCO2−. (d) Draw the complete Lewis electron-dot diagram for a molecule of propanoic acid. AP® CHEMISTRY 2012 SCORING GUIDELINES (INTERNATIONAL) Question 6 (continued) (c) Indicate the hybridization of the carbon atom in each of the following: (i) Methanol sp3 One point is earned for the correct hybridization. © 2012 The College Board. Single bonds between atoms of the same two elements the single. The electrons are shared equally between the two for the correct carbon-oxygen bonds in the methanoate anion.collegeboard. You may draw a Lewis electron-dot diagram (or diagrams) of the methanoate ion as part of your explanations. B Scoring Worksheet The following provides a worksheet and conversion table used for calculating a composite score of the exam. . 6666 = ____________ (out of 9) (Do not round) Question 4 ___________ × 0.4062 = ____________ (out of 8) (Do not round) Question 6 ___________ × 1.2500 = ____________ (out of 9) (Do not round) Sum = ____________ Weighted Section II Score (Do not round) Composite Score ________________ + ________________ = _______________ Weighted Weighted Composite Score Section I Score Section II Score (Round to nearest whole number) AP Score Conversion Chart Chemistry Composite Score Range AP Score 110-150 5 92-109 4 73-91 3 58-72 2 0-57 1 .6666 = ____________ (out of 9) (Do not round) Question 3 ___________ × 1.5000 = ____________ (out of 10) (Do not round) Question 2 ___________ × 1. 2012 AP Chemistry Scoring Worksheet Section I: Multiple Choice ______________ × 1.0000 = _____________________ Number Correct Weighted Section I Score (out of 75) (Do not round) Section II: Free Response Question 1 ___________ × 1.5000 = ____________ (out of 15) (Do not round) Question 5 ___________ × 1. . Visit the College Board on the Web: www. the College Board was created to expand access to higher education. The organization also serves the education community through research and advocacy on behalf of students. AP Chemistry The College Board The College Board is a mission-driven not-for-profit organization that connects students to college success and opportunity. and concerns. activities. educators. Today. The College Board is committed to the principles of excellence and equity. the College Board helps more than seven million students prepare for a successful transition to college through programs and services in college readiness and college success — including the SAT® and the Advanced Placement Program®. the membership association is made up of over 6.000 of the world’s leading educational institutions and is dedicated to promoting excellence and equity in education.collegeboard. .org. Each year. and schools. Founded in 1900. services. and that commitment is embodied in all of its programs.