250+ TOP MCQs on Kinetics of Homogeneous Reactions-Comparison of Theories-2 and Answers

Chemical Reaction Engineering Multiple Choice Questions on “Kinetics of Homogeneous Reactions – Comparison of Theories – 2”.

1. Which of the following pairing is incorrect? (Where A is the frequency factor)
A. Arrhenius equation; k = A(e^{frac{-Ea}{RT}} )
B. Transition state theory; k = AT(e^{frac{-Ea}{RT}} )
C. Collision theory; k = AT^0.5(e^{frac{-Ea}{RT}} )
D. Arrhenius equation; k = AT²(e^{frac{-Ea}{RT}} )

Answer: D
Explanation: Arrhenius equation: k = A(e^{frac{-Ea}{RT}} ).
By collision theory, k α T^0.5
By transition state theory, k α T

2. The activation energy for a reaction is 122137.5 J/ mol. If the rate constant at 330K is 0.5 min^-1, then the value of rate constant (in min^-1) at 360K by Arrhenius law is ____
A. 20.42
B. 18.65
C. 30.12
D. 12.32

Answer: A
Explanation: ln((frac{k_2}{k_1}) = -frac{E}{R} (frac{1}{T_2} – frac{1}{T_1}) )
ln((frac{k_2}{0.5}) = -frac{E}{8.314} (frac{1}{360}- frac{1}{330}) )
k₂ = 20.42 min^-1.

3. If the rate constant of a reaction at 275K is 1 min^-1 and the rate constant at 300K is 2 min^-1, what is the activation energy (in J/ mol) as obtained by Arrhenius law?
A. 24655
B. 19019.14
C. 366543.2
D. 18989.32

4. If the rate constant of a reaction at 600K is 100 times the rate constant at 500K, then the value of the activation energy obtained by Transition state theory is ____
A. 120987.12
B. 167435.15
C. 110319.28
D. 156435.54

Answer: C
Explanation: By Transition state theory, ln((frac{k_2}{k_1}) = -frac{E}{R} (frac{1}{T_2} – frac{1}{T_1}) + ln(frac{T_2}{T_1}) )
ln((frac{100k_1}{k_1}) = -frac{E}{8.314} (frac{1}{600} – frac{1}{500}) + ln(frac{600}{500}) )
E = 110319.28.

5. The activation energy of a reaction is 155326 J/ mol. The rate constant of the reaction at and 300K as a function of rate constant at 400K, obtained by the Collision theory is ____
A. k₁ = 1.5 × 10^-7k₂
B. k₁ = 1.2 × 10^-6 k₂
C. k₁ = 1.5 × 10^-6 k₂
D. k₁ = 1.2 × 10^-7 k₂

Answer: A