## Calculating A for the Arrhenius Equation, quest. 15.63

Arrhenius Equation: $\ln k = - \frac{E_{a}}{RT} + \ln A$

Jake Ney lecture 1 discussion 1F
Posts: 26
Joined: Fri Sep 25, 2015 3:00 am

### Calculating A for the Arrhenius Equation, quest. 15.63

15.63 asks: The rate constant of the reaction between CO2 and OH- in aqueous solution to give the HCO3- ion is 1.5x10^10 L/mol*s at 25 degree C. Determine the rate constant at blood temperature (37 degree C), given that the activation energy for the reaction is 38 kJ/mol*s.

I'm assuming that you plug the given values into the Arrhenius Equation to solve for K, but how do you first determine [A], and which compound (CO2, OH- or HCO3-) do we need the concentration of?

Lisa Leung 2H
Posts: 23
Joined: Fri Sep 25, 2015 3:00 am

### Re: Calculating A for the Arrhenius Equation, quest. 15.63

You will have the Arrhenius equations for the two temperatures and subtract the two. So, at T1: $lnk_{1} = ln A - \frac{E_{a}}{RT_{1}}$ and at T2: $lnk_{2} = ln A - \frac{E_{a}}{RT_{2}}$. lnA is eliminated when we subtract the two equations and we get $lnk_{2} - lnk_{1} =- \frac{E_{a}}{RT_{2}} + \frac{E_{a}}{RT_{1}}$.
Hope this helps!