Question

Arrhenius studied the effect of temperature on the rate of a reaction and postulated that rate constant varies with temperature exponentially as $k=A{e}^{-\frac{E_a}{RT}}$ This method is generally used for finding the activation energy of a reaction. Keeping temperature constant, the effect of catalyst on the activation energy has also been studied.
The pre-exponential factor in the Arrhenius equation of a first order reaction has the unit:

• A. $mol‘L6–1s^{–1}$
• B. $Lmo{l}^{–1}{s}^{–1}$
• C. $s^{–1}$
• D. dimensionless

Answer 1

The correct option is C $s^{–1}$

$e^{-\frac{E_a}{RT}}$ is fraction of molecules having energy greater than activation energy $\left(E_a\right)$, it is dimensionless. So A has same unit of K. For $1^{st}$ order reaction unit of K is $s^{–1}$.