CBSE Class 12 Chemistry - Important Formulas all chapters.pdf



Comments



Description

Downloaded from www.studiestoday.com Important Formulas of Physical Chemistry THE SOLID STATE 1. Calculation of numer of particles / atoms / ions in a Unit Cell : 2. Type of Numer of Relationship Unit Cell particles per between edge Unit Cell length (a) and radius (r) of atom/ion Simple cubic 1 a = 2r 4 Body centred cubic 2 a = r 3 Face centred cubic 4 a = 2 2 r 3. Density of unit cell (d) Z ×M d= a3 × NA Where Z is rank of unit cell (no. of atoms per unit cell), m is molar mass/ atomic mass, ‘a’ is edge length of the cube, ‘a3’ is volume of cubic unit cell and NA is Avogatro number. d × NA 4 3 4. Packing efficiency = × π r × 100 M 3 Here ‘M’ is molar mass ‘r’ is radius of atom, ‘d’ is density and NA is Avogaotro’s number (6.022  1023 mol–1). Rank of unit cell can be computed by packing efficiency value Type of Packing Rank of Unit Cell efficiency Unit Cell SC 52.4% 1 BCC 68.% 2 FCC 74% 4 5 XII – Chemistry Downloaded from www.studiestoday.com 6. Raoults law for a solution of non-volatile solute and volatile solvent : pA ° – pA n WB × MA = i xB  i B = i (for dilute solution) pA ° NA MB × WA pA ° – pA Where xB is mole fraction of solute. Raoult’s law for a solution of volatile solute in volatile solvent : pA = pA° xA pB = p B° x B Where pA and pB are partial vapour pressures of component ‘A’ and component ‘B’ in solution. and xB = nA + nB nA +nB xA + xB = 1 Moles of solute 2. Moality (m) = Mass of solvent in kilograms 4. Parts per million (ppm) Number of parts of the component = × 10 6 Total number of parts of all components of the solution 5. pA° and pB° are vapour pressures of pure components ‘A’ and ‘B’ respectively. i is van’t Hoff factor and is pA ° relative lowering of vapour pressure. Mole fraction (x) if the number of moles of A and B are nA and nB respectrively.com . 6 XII – Chemistry Downloaded from www.studiestoday. the mole fraction of A and B will be x nB xA = . Molarity (M) = Volume of solution in litres Moles of solute 3. Downloaded from www.studiestoday.com Solution 1. com . Elevation in boiling point (Tb) Tb = i. Van't Hoff factor (i) Observed colligative property i= Theoretically calculated colligative property Normal molar mass i= Abnormal molar mass 7 XII – Chemistry Downloaded from www. Osmotic pressure () of a solution V = inRT or  = i CRT where  = osmotic pressure in bar or atm V = volume in litres i = Van't Hoff factor c = molar concentration in moles per litres n = number of moles T = Temperature on Kelvin Scale R = 0.083 L bar mol–1 K–1 R = 0. 9.studiestoday. Downloaded from www.studiestoday.0821 L atm mol–1 K–1 10.Kb m where T b = T b – T b° Kb = molal boiling point elevation constant m = molality of solution.Kf m where T f = T f° – T f Kf = molal depression constant m = molality of solution.com 7. Depression in freezing point (Tf ) Tf = i. 8. studiestoday.studiestoday.p. Relationship between relative lowering in vapour prescure and elevation in b. its limiting molar conductivity is given by m = +  + – °– Here ° and °– are the limiting molar conductivities of cation and anion respectively and + and – are the number of cations and anions furnished by one formula unit. Kohlrausch’s law (a) In general if an electrolyte on dissociation gives  + cations and – anions then.com . l/A = cell constant (G*) and is resistivity. 8 XII – Chemistry Downloaded from www. P 2. i is van't Hoff factor. Conductivity (k) 1 1 l K= = × = G × G* P R A 1 Where R is resistance. k is conductivity and C is molar concentration. pA° is vapour pressure of pure solvent.. Downloaded from www. Relationship between k and Λ m 1000 × k Λm = c Where Λ m is molar conductance. Kb is molal elevation constant and MA is molar mass of solvent Electrochemistry 1. ∆p ∆Tb =i MA × 1000 pA ° Kb Here p is lowering in vapour pressure. Tb is elevation in boiling point.com i > 1 For dissociation of molecules  i < 1 For association of molecules i = 1 For ideal solution  11. G = – 2. G = – nF Ecell Where G = standard Gibbs energy change and nF is the amount of charge passed. Nernst Equation for electrode reaction : Mn+ + ne–  M.303 RT log Kc 9 XII – Chemistry Downloaded from www. 2.com .303 RT 1 E = Eθ – log nF [Mn+ ] – ne For Cell potential of electrochemical reaction aA : bB  → cC + dD 2.059v Eθ cell = log KC n 5. (c) Dissociation constant (K. Downloaded from www.303RT = Eθcell – Ecell log [QC ] nF 4.com (b) Degree of dissociation () is given by : c Λ α = m° Λm Here °m is molar conductivity at the concentration C and °m is limiting molar conductivity of the electrolyte. Relationship between E° cell and equilibrium constant (Kc) 2.303RT E θ cell = log K C nF 0.studiestoday.) of weak electrolyte 2  Λ cm  C  Λ om  Cα 2 K= = 1–α  Λm   1– Λ o  m 3.studiestoday. studiestoday. R is universal gas contant and T is absolute temperature.com Chemical Kinetics 1.303 R  T T  2 a 2 1 (b) 1 1 2 Where k1 is rate constant at temperature T1 and k2 is rate constant at temperature T 2.com . [R]° is initial molar concentration and [R] is final concentration at time ‘t’. k E T –T  log k = 2. Ea is the energy of activation. –Ea/ RT gives the fraction of collisions having energy equal to or greater than Ea. (b) Half life period ( t 12 ) for first order reaction : 0. Integrated rate law equation for first order reaction 2. Integrated rate law equation for zero order reaction [R]  – [R] (a) k = t Where k is rate constant and [R]0 is initial molar concentration. 2 2. Anhenius epuation (a) k = A –Ea/RT e Where ‘A’ is frequency factor. Downloaded from www.693 t1 = 2 k 3.studiestoday.303 log [R] (a) k = t [R ] Where k is rate constant. t1 = [R]  (b) 2 2k t1 is half life period of zero order reaction. 10 XII – Chemistry Downloaded from www.
Copyright © 2024 DOKUMEN.SITE Inc.