Question

Consider the Arrhenius equation, $k=A{e}^{-E_a/\left(RT\right)}$, which of the following would not increase the rate constant of the reaction?

• A. A new value of the constant $A$ was calculated, this new value being higher than the previous one
• B. The temperature of the reaction is increased
• C. Experiments have revealed that the previously accepted activation energy of the reaction was calculated incorrectly. The new value is larger.
• D. The universal gas constant was redetermined to a smaller value

Answer 1

Answer: (C)

Experiments have revealed that the previously accepted activation energy of the reaction was calculated incorrectly. The new value is larger.

$k={A.e}^{{-E}_a/RT}$

(i) If the value of $A$ increases, the value of $k$ increases.

(ii) If the value of $T$ increases, $E_a/RT$ decreases. Therefore $e^{{-E}_a/RT}$ increases. Therefore, $k$ increases.

(iii) If $E_a$ increases,$e^{{-E}_a/RT}$ decreases. Therefore, $k$ decreases.

(iv) If $R$ increases, $e^{{-E}_a/RT}$ increases. Therefore, $k$ increases.