Question

The rate constant for a first order reaction at $300^{^{\circ}}C$ for which $E_a$ is $35\, kcal\, mol^{-1}$ and frequency constant is $1.45\times10^{11}s^{-1} $ is

• A. $10\times10^{-2}s^{-1}$
• B. $ 5.37\times10^{-10}s^{-1}$
• C. $ 5\times10^{-4}s^{-1}$
• D. $ 7.94\times10^{-3}s^{-1}$

Answer 1

Answer: (D)

$log \,k=log \,A-\frac{E_{a}}{2.303 RT}$
$log k=log\left(1.45\times10^{11}\right)$ $-\frac{35\times10^{3}}{2.303\times2\times573}$
$log\, k=11.16-13.26=-2.1$
Taking antilog, $k=7.94\times10^{-3}$ $s^{-1}$