CHEMICAL KINETICS QUIZ-5

Q1. For a reaction, the rate constant is 2.34s^(-1). The half-life period for reaction is

•  Data is insufficient
•  3.3 s
•  0.60 s
•  0.30 s

Solution
K=2.34s^(-1) Unit of k suggest that the reaction is of 1st order, hence for 1st order reaction, t_(1/2)=0.693/k =0.693/2.34=0.30s

Q2.Effect of temperature on reaction rate is given by

•  Claisen-Clapeyron equation
•  Arrhenius equation
•  Kirchoff’s equation
•  Gibbs Helmholtz equation

Solution
Effect of temperature on reaction rate is given by Arrhenius equation k=Ae^(-E_a/RT)

Q3.  The rate constant for a chemical reaction has units L mol^(-1) s^(-1),order of the reaction will be

•   1
•  3
•  0
•  2

Solution

Q4. For the non-equilibrium process, A+B⟶ Products, the rate is first order with respect to A and second order respect to B. If 1.0 mole each of A and B are introduced into a 1 litre vessel and the initial rate was 1.0×〖10〗^(-2) mol/litre-sec. The rate (in mol litre^(-1) sec^(-1)⁡ ) when half of the reactants have been used:

•  None of these
•  2.5×〖10〗^(-4)
•  1.2×〖10〗^(-2)
•  1.2×〖10〗^(-3)

Solution

Q5.Rate constant for a reaction is 〖10〗^(-3) s^(-1). The to leave 25% reaction is

•  1386 s
•  6930 s
•  2029 s
•  693 s

Solution
 

Q6. A zero order reaction is one:

•  In which reactants do not react
•  Whose rate does not change with time
• In which one of the reactants is in large excess
•  Whose rate increases with time

Solution
Zero order reactions occur with constant rate.

Q7.The units of the rate constant of a second order reaction are

•  mol^(-1) L^(-1) s^(-1)
•  mol^(-1) Ls
•  mol^(-1) Ls^(-1)
•  mol L^(-1) s^(-1)

Solution

Q8.The rate constant of a reaction is found to be 3×〖10〗^(-3) mol L^(-1) min┴(-1)⁡ . The order of reaction is

•  1
•  Zero
•  2
•  1.5

Solution

Q9.For the elementary step, (CH_3 )_3∙CBr(aq)⟶(CH_3 )_3 C^+ (aq)+Br^- (aq) the molecularity is:

•  Zero
•  Cannot ascertained
•  2
•  1

Solution
Molecularity represents the number of molecules of reactants taking part in an elementary step of reaction

Q10. Which of the following statement is incorrect about the molecularity of a reaction?

•  Molecularity is always a whole number
•  There is no difference between order and molecularity of a reaction
•  Molecularity of a reaction is the number of molecules in the slowest step
• Molecularity of a reaction is the number of molecules of the reactants presents in the balanced equation

Solution
Order may or may not be equal to molecularity.