Question

What is the frequency factor?
A) The number of times that reactants approach the activation energy per unit of time.
B) The number of times reactants get over activation energy hill.
C) The amount of energy a reaction needs to get started.
D) The number of times that products approach the activation energy per unit time.
E) The number of times products get over the activation energy hill.

Answer 1

Hint: The term frequency factor can be related to the pre-exponential factor in the Arrhenius equation. One can think about the terms of the frequency factor in the Arrhenius equation and decide which option is the correct choice.

Complete step by step answer:
1) First of all we will see the formula of the Arrhenius equation and the terms within it which can lead us to the meaning of the frequency factor. The formula of the Arrhenius equation is as below,
$k = A{e^{\dfrac{{ - {E_a}}}{{RT}}}}$
In the above equation, the term A is the pre-exponential factor
The term Ea is the activation energy
The term T is the temperature
The term R is the value of the gas constant
2) Now in the above equation formula the term A i.e. pre-exponential factor is the value that can be calculated experimentally or numerically. The term pre-exponential factor can also be called the frequency factor.
3) The term frequency factor in the above equation formula describes the number of times two molecules in a reaction collide with each other. This factor is also considered as a constant value.
When molecules collide, they get over the activation energy hence, the frequency factor is the number of times products get over the activation energy hill which shows option D as the correct choice.

Note:
The pre-exponential factor or the frequency factor is also dependent on the temperature as the term is related to molecular collision and it is also the function of the temperature. The units of the pre-exponential factor or the frequency factor change according to the order of the reaction.