Chapter 6 Chemical Kinetics Class 12 Chemistry Maharashtra Board Textbook Solution
1. Choose the most correct option.
i. The rate law for the reaction aA + bB P is rate = k[A] [B]. The rate of reaction doubles if
a. concentrations of A and B are both doubled. b. [A] is doubled and [B] is kept constant c. [B] is doubled and [A] is halved d. [A] is kept constant and [B] is halved.
x. For an endothermic reaction, X Y. If Ef is activation energy of the forward reaction and Er that for reverse reaction, which of the following is correct? a. Ef = Er
ii. For the reaction, CH3Br(aq) + OH-(aq) CH3OH (aq) +Br (aq), rate law is rate = k[CH3Br][OH ] a. How does reaction rate changes if [OH ] is decreased by a factor of 5 ? b. What is change in rate if concentrations of both reactants are doubled?
iii. What is the relationship between coefficients of reactants in a balanced equation for an overall reaction and exponents in rate law. In what case the coefficients are the exponents?
vi. What are the units for rate constants for zero order and second order reactions if time is expressed in seconds and concentration of reactants in mol/L?
iii. A reaction takes place in two steps, 1. NO(g) + Cl2(g) NOCl2(g) 2. NOCl2(g) + NO(g) 2 NOCl(g) a. Write the overall reaction. b. Identify reaction intermediate. c. What is the molecularity of each step?
i. In a first order reaction, the concentration of reactant decreases from 20 mmol dm-3 to 8 mmol dm-3 in 38 minutes. What is the half life of reaction? (28.7 min)
iii. The energy of activation for a first order reaction is 104 kJ/mol. The rate constant at 25 0C is 3.7 × 10-5 s-1. What is the rate constant at 300C? (R = 8.314 J/K mol) (7.4 × 10-5)
v. The rate constant of a reaction at 5000C is 1.6 × 103 M-1s-1. What is the frequency factor of the reaction if its activation energy is 56 kJ/mol. (9.72 × 106 M-1s-1)
viii. The rate constant for the first order reaction is given by log10 k = 14.34 – 1.25 × 104 T. Calculate activation energy of the reaction. (239.3 kJ/mol)