Question

What is the ΔG for the following reaction at 25°C?
N2O4(g) → 2NO2(g)
Given:
N2O4(g):ΔG= 98.28 kJ per mole
NO2(g):ΔG= 51.8 kJ per mole

Answer 1

$\Delta G_{global}=\Delta G_{products}-\Delta G_{reagents}\\\\ \text{We should consider the stoichiometry:}\\\\ \Delta G=2\Delta G_{NO_2}-\Delta G_{N_2O_4}\\\\ \Delta G=2\cdot51.8-98.28=103.6-98.28\\\\ \boxed{\Delta G=5.32~kJ}$

Answer 2

 The ΔG for the following reaction at 25°C of N2O4(g) → 2NO2(g) is 5.32 kJ per mole.

2 (51.8) - 98.28 = 5.32 kJ per mole.

This is because the rate of the dissociation of N2O4 is equal to the rate of formation of N2O4.