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Activation Enthalpy and Arrhenius Equation

Im trying to find the activation enthalpy of the reaction between iodide ions and peroxodisulphate ions. Different sources say to either draw a graph of lnk against 1/T or draw lnRate against 1/T and find the gradient to the Ea. Which do you do surely lnk and lnRate arnt the same arnt they linked by
k= rate / [I-] [S2O8 2-] :s:

s

I understand k = A e-Ea/RT
and so
ln k = -Ea/R x 1/T + ln A
so woulfnt the gradient be -Ea/R and not Ea :s-smilie:

wouldnt you have to multipy it by -R to get the Ea?

Help lol!

Reply 1

charco

Study Forum Helper

yes, the log form of the Arrhenius equation takes the form y = mx + c, where m is the gradient and c the intercept with the y axis.

If you graph lnk against 1/T, the gradient is -Ea/R and the intercept is lnA