1. The rate constant for a second order reaction has units of L mol^-1 s^-1. What are the units of the frequency factor, A, for a second order reaction?
I copied this from Wikipedia.
"The units of the pre-exponential factor A are identical to those of the rate constant and will vary depending on the order of the reaction. If the reaction is first order it has the units s−1, and for that reason it is often called the frequency factor or attempt frequency of the reaction. Most simply, k is the number of collisions that result in a reaction per second, A is the number of collisions (leading to a reaction or not) per second occurring with the proper orientation to react[6] and e^{{-E_a}/{(RT)}}\ \ \ is the probability that any given collision will result in a reaction. It can be seen that either increasing the temperature or decreasing the activation energy (for example through the use of catalysts) will result in an increase in rate of reaction."
So the answer is L/mol*sec
To determine the units of the frequency factor, A, for a second order reaction, we need to consider the overall units of the rate constant.
The rate constant (k) for a second order reaction is given by the equation:
k = A * [reactant]^(n-1)
Where:
- A is the frequency factor,
- [reactant] is the concentration of the reactant, and
- n is the order of the reaction.
In this case, we have a second order reaction, where n = 2.
Now let's examine the units of the rate constant (k). We are given that the units of k are L mol^(-1) s^(-1), which means that the units of the frequency factor (A) must cancel out the units of concentration [reactant]^(n-1) to give the desired units for k.
Since the units of concentration [reactant] will be in mol/L, we can rearrange the equation for k:
k = A * [reactant]^1
Now, let's consider the units of A. To cancel out the units of concentration [reactant], the units of A must be L^(n-1). In this case, since n = 2, the units of A will be L^(2-1) = L mol^(-1) s^(-1), which is the same as the given units for k.
Therefore, the units of the frequency factor, A, for a second order reaction are L mol^(-1) s^(-1).