EudiometryEudiometry or gas analysis involves the calculations based on gaseous reactions or the reactions in which at least two components are gaseous, in which the amounts of gases are represented by their volumes, measured at the same pressure and temperature. Some basic assumptions related with calculations are: 1. Gay-Lussac's law of volume combination holds good. According to this law, the volumes of gaseous reactants reacted and the volumes of gaseous products formed, all measured at the same temperature and pressure, bear a simple ratio. N2 (g) + 3H2 (g) 2NH3 (g) 1 vol. 3 vol. 2 vol. Problem may be solved directly is terms of volume, in place of mole. 2. The volumes of solids or liquids is considered to be negligible in comparison to the volume of gas. It is due to the fact that the volume occupied by any substance in gaseous state is even more than thousand times the volume occupied by the same substance in solid or liquid states. 2H2 (g) + O2 (g) 2H2O (l) 2 mole 1 mole 2 mole 2 vol. 1 vol. 0 vol. 3. Air is considered as a mixture of oxygen and nitrogen gases only. It is due to the fact that about 99% volume of air is composed of oxygen and nitrogen gases only. 4. Nitrogen gas is considered as an non- reactive gas. It is due to the fact that nitrogen gas reacts only at very high temperature due to its very high thermal stability. Eudiometry is performed in an eudiometer tube and the tube can not withstand very high temperature. This is why, nitrogen gas can not participate in the reactions occurring in the eudiometer tube. EUDIOMETRY : [For reactions involving gaseous reactants and products] The stoichiometric coefficient of a balanced chemical reactions also gives the ratio of volumes in which gaseous reactants are reacting and products are formed at same temperature and pressure. The volume of gases produced is often given by mentioning certain solvent which absorb contain gases. Solvent gas (es) absorb KOH CO2, SO2, Cl2 Ammonical Cu2Cl2 CO Turpentine oil O3 Alkaline pyrogallol O2 water NH3, HCl CuSO4 /CaCl2 H2O Check out for certain assumption which are to be used for solving problem related to this. EXERCISE # I Q.1 10 ml of a mixture of CO, CH4 and N2 exploded with excess of oxygen gave a contraction of 6.5 ml. There was a further contraction of 7 ml, when the residual gas treated with KOH. Volume of CO, CH4 and N2 respectively is Q.2 When 100 ml of a O2 – O3 mixture was passed through turpentine, there was reduction of volume by 20 ml. If 100 ml of such a mixture is heated, what will be the increase in volume? Q.3 60 ml of a mixture of nitrous oxide and nitric oxide was exploded with excess of hydrogen. If 38 ml of N2 was formed, calculate the volume of each gas in the mixture. Q.4 When a certain quantity of oxygen was ozonised in a suitable apparatus, the volume decreased by 4 ml. On addition of turpentine the volume further decreased by 8 ml. All volumes were measured at the same temperature and pressure. From these data, establish the formula of ozone. Fateh Verma Eudiometry Q.5 ml. 8 ml of oxygen remained. Determine the composition of original mixture. is (A) N2O (B) NO2 (C) N2O3 (D) N2O5 Q. CH4 and CO is 40.D.9 10 ml of a mixture of CH4. Now 30 ml of O2 were added and sparking was continued again. the volume becomes 48 ml. the fraction of C2H2 in mixture is (A) 0. after the explosion the volume of the products [CO2(g) and H2O(g)] was found to be 700 ml under the similar conditions.5 : 13.8 Calculate the volume of CO2 evolved by the combustion of 50 ml of a mixture containing 40% C2H4 and 60% CH4 (by volume) Q. There was a volume contraction of 23 mL. Determine the volume ratio V1 : V2 of CO and H2 in the original mixture (A) 6. Q. When 200 ml of the mixture is burnt in excess of O2. The sparks were continued till there was no further increase in volume. When the resulting gases were passed through KOH solution it reduces by 50 % then calculate the volume ratio of VCO : VCO : VN in original mixture.10 40 ml of a mixture of C2H2 and CO is mixed with 100 ml of O2 gas and the mixture is exploded. V. All the volume are at same the temperature and pressure. The volume after sparking measured 20 ml.5 10 ml of ammonia were enclosed in an eudiometer and subjected to electric sparks.6 20 ml of a mixture of C2H2 and CO was exploded with 30 ml of oxygen. there was further reduction of 14 ml.4 200 ml of a gaseous mixture containing CO. EXERCISE # II Single correct Q. The mixture was completely burnt to CO2 and H2O(l).5 (C) 0.7 10 ml of CO is mixed with 25 ml air having 20% O2 by volume.25 Q. 2 2 (A) 4 : 1 : 5 (B) 2 : 3 : 5 (C) 1 : 4 : 5 (D) 1 : 3 : 5 Q. What is the composition of the mixture? Q. Calculate the composition of the mixture. All volumes were measured under identical conditions of temperature and pressure. (A) 220 (B) 340 (C) 440 (D) 560 Fateh Verma Eudiometry .7 20 mL of a mixture of CO and H2 were mixed with excess of O2 and exploded & cooled.125 (B) 0. The volume of all reactants was 600 ml. Q. there was contraction on cooling of 17 ml and after treatment with KOH. Molecular formula of compound if both reactants reacts completely. of ammonia is 8. Calculate the molecular formula of ammonia. The molecular formula of the compound is (A) C3H8 (B) C3H6 (C) C3H4 (D) C4H10 Q. On treatment with KOH. is (A) 30 ml (B) 60 ml (C) 20 ml (D) 10 ml Q. After explosion. What would be the final volume if none of CO and O2 is left after the reaction? Q.2 C6H5OH (g) + O2 (g) CO2 (g) + H2O (l) Magnitude of volume change if 30 ml of C6H5OH (g) is burnt with excess amount of oxygen.5 (B) 5 : 15 (C) 9 : 11 (D) 7 : 13 Q. Nitrogen and Hydrogen are diatomic.8 The % by volume of C4H10 in a gaseous mixture of C4H10.85 (D) 0. The residual gases occupied 104 ml and when these are passed through KOH solution.3 10 ml of a compound containing 'N' and 'O' is mixed with 30 ml of H2 to produce H2O (l) and 10 ml of N2 (g). CO2 and N2 on complete combustion in just sufficient amount of O2 showed contraction of 40 ml.5 When 20 ml of mixture of O2 and O3 is heated. The new volume then measured 27. The gases after the reaction had a volume of 34 ml. the volume becomes 29 ml and disappears in alkaline pyragallol solution. All volume measurements corresponds to room temperature (27°C) and one atmospheric pressure.5. Find volume (in ml) of CO2 produced. C2H4 and CO2 were exploded with excess of air.6 A mixture of C2H2 and C3H8 occupied a certain volume at 80 mm Hg. When the pressure of CO2 was found to be 230 mm Hg at the same temperature and volume. What is the volume precent of O2 in the original mixture? (A) 90% (B) 10% (C) 18% (D) 2% Q.1 A definite amount of gaseous hydrocarbon was burnt with just sufficient amount of O2. Which of the following option(s) satisfy the given conditions. (A) 10 ml C3H8 + 110 ml O2 (B) 20 ml C2H6O + 80 ml O2 (C) 10 ml C3H6O2 + 50 ml O2 (D) 40 ml C2H2O4 + 60 ml O2 Comprehension: Q.9 Two gases A and B which react according to the equation aA(g) + bB(g) cC(g) + dD(g) to give two gases C and D are taken (amount not known) in an Eudiometer tube (operating at a constant Pressure and temperature) to cause the above.11 A mixture of 100 ml of CO. 20 ml (C) 50 ml. 20 ml (D) 30 ml. There was contraction of 2 ml. On sparking II only partial decomposition of NH3 took place and the resulting mixture on passing through water showed a concentration by 20 ml.10 A mixture of C3H8 (g) & O2 having total volume 100 ml in an Eudiometry tube is sparked & it is observed that a contraction of 45 ml is observed what can be the composition of reacting mixture. ClOP (P an integer) and NH3 in the molar ratio 1 : 4 : 6 having a total volume 110ml is taken and underwent sparking I. a alkane & O2 undergo combustion in Eudiometry tube. CO2 and O2 was sparked. (C) Vapour Density of the mixture will remain same throughout the course of reaction. If on causing the reaction there is no volume change observed then which of the following statement is/ are correct.13 A 10 ml mixture of N2. From this information calculate (i) Formula of oxide of chlorine (A) ClO2 (B) Cl2O (C) ClO (D) Cl2O7 Fateh Verma Eudiometry . causing only decomposition of oxide of chlorine to Cl2 (gas) and O2 (gas) resulting a rise in volume by 20 ml. contraction in volume was found to be 80 ml.14 A gaseous mixture of Cl2. (a) Gas produced after introduction of H2 in the mixture? (A) H2O (B) CH4 (C) CO2 (D) NH3 (b) Volume of N2 present in the mixture? (A) 2 ml (B) 4 ml (C) 6 ml (D) 8 ml (c) Volume of O2 remained after the first combustion? (A) 4 ml (B) 2 ml (C) 0 (D) 8 ml (d) Identify the hydrocarbon.More than one correct: Q. causing a reduction in volume of 8 ml. On sparking III of the resulting mixture some drops of water were formed with only one more product and the mixture when passed through KOH (absorbs Cl2 only) showed no volume change. 30 ml Q. 50 ml. which results in 25% volume contraction. (A) CH4 (B) C2H6 (C) C3H8 (D) C4H10 Q. (A) 15 ml C3H8 & 85 ml O2 (B) 25 ml C3H8 & 75 ml O2 (C) 45 ml C3H8 & 55 ml O2 (D) 55 ml C3H8 & 45 ml O2 Q. 60 ml. Q. (A) (a + b) = (c + d) (B) average molecular mass may increase or decrease if either of A or B is present in limited amount. 30 ml. when residual gases are passed through KOH. To the remaining mixture comprising of only one gas excess H2 was added & after combustion the gas produced is absorbed by water. (D) Total moles of all the component of mixture will change. 10 ml (B) 30 ml. the composition of initial mixture may be (in the same order) (A) 30 ml. When the resulting gaseous mixture was passed through KOH solution. 40 ml.12 An organic compound is burnt with excess of O2 to produce CO2(g) and H2O(l). 3 ml Q. C Q.10 C2H2 = 16 ml. B Q.10 A.3 NO = 44 ml.(ii) Percentage decomposition of NH3 on sparking (A) 66.2 B Q. CO = 24 ml EXERCISE # II Q.4 C Q. N2O = 16 ml Q.5 ml Q. 2 ml. CO = 14 ml Q. B Q.9 A.67 (B) 33.7 30 ml Q.9 CH4 = 4.6 C2H2 = 6 ml. CO2 = 1. (A) 25 (B) 10 (C) 45 (D) none of these ANSWER KEY EXERCISE # I Q.8 C Q.3 C Q.4 O3 Q.1 5 ml.33 (C) 50% (D) none of these (iii) Reactions which would have occured on sparking III(one or more than one) (A) H2 + Cl2 HCl (B) 3H2 + N2 2NH3 1 (C) H2 + O2 H2O(l) (D) Data insufficient 2 (iv) Volume change that would be observed when the mixture after III sparking is over is passed (through alkaline pyragallol).5 B Q.6 A Q. C (iv) A Fateh Verma Eudiometry . C Q.13 (a) D (b) B (c) C (d) A Q.1 A Q.7 D Q.5 NH3 Q.2 10 ml Q.14 (i) A (ii) A (iii) A.11 A.12 A.5 ml.8 70 ml Q.