[hallie3]

Use the thermodynamic data provided below to determine ΔG (in kJ/mol) for the vaporization of CCl4 at 139.15 °C if the initial partial pressure of CCl4 is 0.5 atm.

Substance       ΔH°f (kJ/mol)       S° (J mol-1K-1)
CCl4 (l)       -128.4              214.4
CCl4 (g)       -96                      309.6

My attempt:
ΔG =-RTlnK
K = ln(0.5) = -0.6931471806
ΔG = -(0.008314)(139.15 + 273.15)(ln(-0.6931471806))
ΔG =2.37 kJ/mol

However, this is wrong. Where have I gone off? Should I be utilizing the ΔS and ΔH values? And if so, how? Thanks in advance!

[Corribus]

How do you calculate a Gibbs energy from entropy and enthalpy?