4. Chemical Kinetics

Activation Energy — Quiz

Test your understanding of activation energy with 5 practice questions.

Practice Questions

Question 1

The rate constant of a reaction is measured at two different temperatures. At $20 \text{ °C}$, the rate constant is $4.0 \times 10^{-5} \text{ s}^{-1}$. At $60 \text{ °C}$, the rate constant is $3.2 \times 10^{-3} \text{ s}^{-1}$. Calculate the activation energy ($E_a$) for this reaction. (Given: $R = 8.314 \text{ J/(mol}\cdot\text{K)}$)

Question 2

An energy profile diagram shows that the activation energy for the forward reaction ($E_{a, \text{forward}}$) is $80 \text{ kJ/mol}$ and the overall enthalpy change ($\Delta H$) for the reaction is $+30 \text{ kJ/mol}$. What is the activation energy for the reverse reaction ($E_{a, \text{reverse}}$)?

Question 3

Which of the following statements accurately describes the effect of a catalyst on the activation energy and the transition state of a chemical reaction?

Question 4

The Arrhenius equation is given by $k = A e^{-E_a/(RT)}$. If a plot of $\ln k$ versus $\frac{1}{T}$ yields a straight line, what does the slope of this line represent?

Question 5

Consider two reactions, Reaction P and Reaction Q, at the same temperature. Reaction P has an activation energy of $30 \text{ kJ/mol}$, while Reaction Q has an activation energy of $60 \text{ kJ/mol}$. Which reaction will proceed faster, and why?