lnk = lnA - Ea / RT question

Please can someone check if this is right?

k = 6.51 x 10^-3 mol-1dm3
T = 300K
A = 2.57 x 10^10 mol-1dm3
R = 8.31 JK-1mol-1

Using lnk = lnA - Ea / RT find Ea in kJmol-1


I did:

ln6.51 x 10^-3 = ln2.57 x 10^10 - Ea / 8.31 x 300
-12550.79... = ln2.57 x 10^10 - Ea
Ea = ln2.57 x 10^10 + 12550.79...
Ea = 12574.768... Jmol-1
Ea = 12.6 kJmol-1 (3.s.f)

I make it 72.3 kJ

I got 72.3kj/mol too. Double check your rearranging. To make it easier, rearrange before you put your numbers in.

I also got 73.2kj/mol. Show us the steps of your rearranging.

ln6.51 x 10^-3 = ln2.57 x 10^10 - Ea / 8.31 x 300
-12550.79... = ln2.57 x 10^10 - Ea
Ea = ln2.57 x 10^10 + 12550.79...
Ea = 12574.768... Jmol-1
Ea = 12.6 kJmol-1 (3.s.f)

ln6.51 x 10^-3 = ln2.57 x 10^10 - Ea / 8.31 x 300
-12550.79... = ln2.57 x 10^10 - Ea

You went wrong at this part. You multiplied the whole left side by RT when it is only EA/RT on the right hand side, not (lnA-Ea/RT) but rather lnA-(Ea/RT).