Topic 16.3: Activation energy

16.3.1 Describe qualitatively the relationship between the rate constant (k) and temperature (T).

We know that the rate of reaction depends on two things: the rate constant, k and the concentrations of reactants, raised to a power. Since increasing temperature has no change of concentration, thus it effects the value of k. So k is a general measure of the rate of reaction at a particular temperature

16.3.2 Determine activation energy (Ea) values from the Arrhenius equation by a graphical method

This is the Arrhenius equation that links all the factors together.

k is the rate constant
A is the Arrhenius constant
R is universal gas constant
T is temperature (K)
Ea is activation energy

By rearranging it, we could plot it on the graph using linear law.

Thus the graph shall look like this:

The x-axis is 1/Temp
The y-axis is ln k
The y-intercept will be ln A
The gradient is Ea/R

Thus finding the gradient will give us Ea/R. Then times the result by the gas constant 8.31 J K^-1 mol^-1 to receive the final answer of Ea.

Ea is in kJ mol^-1