Question

The enthalpy difference between the axial and equatorial conformers of methylcyclohexane is 7.11 kj/mol. assuming that the entropy difference between these two conformers is negligible, calculate the equilibrium constant at room temperature for the process

Answer 1

There are two equations of Gibb's free energy, ΔG°:

ΔG° = ΔH° - TΔS°
ΔG° = -RTlnK

Let's use the first equation. Since ΔS° is negligible, it is equal to 0. Therefore, ΔG° = ΔH° = 7.11 kJ/mol. We use this value to the second equation.

7.11 kJ/mol = -(8.314 J/mol·K)*(1 kJ/1000 J)*(25 + 273 K)*(lnK)
lnK = -2.8697
K = 0.05671

Therefore, the equilibrium constant is equal to 0.05671.