# Chemistry (physical)

posted by
**Alice**
.

At room temperature (25 degrees C) butane is a mixture of 72% anti and 28% gauche conformations. Calculate the difference in energy between the gauche and anti confromations.

This is how I calculated it but I am not sure I am right:

Boltzmann equation: N2/N1 = exp(-(E2-E1)/RT)

By rearranging: E2-E1 = -RTln(N2/N1)

E2-E1 = -8.314JK^-1mol^-1 x 298K x ln(28/72)

= 2340Jmol^-1

=0.56kcalmol-1

I looked up the correct value on the internet and found it to be around 0.9kcalmol^-1. Have I gone wrong somewhere?