Question

How do you solve the Arrhenius equation?

Answer 1

The Arrhenius equation is:

`\mathbf(k = Ae^(-E_a"/"RT))`

where:

• `k` is the rate constant, in units that depend on the rate law. For instance, if `r(t) = k[A]^2`, then `k` has units of `"M"/"s" * 1/"M"^2 = 1/("M"cdot"s")`.
• `A` is the "pre-exponential factor", which is merely an experimentally-determined constant correlating with the frequency of properly oriented collisions.
• `E_a` is the activation energy in units of, say, `"J"`.
• `R` is the universal gas constant. Using `"J"`, `R = "8.314472 J/mol"cdot"K"`.
• `T` is temperature in `"K"`.

People can determine the temperature themselves when they experimentally figure out the rate constant, so you can assume that you know `T` and `k`. The only values in the Arrhenius equation not known are generally `A` and `E_a`, the pre-exponential factor and activation energies.

I go into how to calculate those here.