The value of ΔG° at 25 °C for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s,rhombic) + 3O₂ (g) → 2SO₃ (g)
Is ________ kJ/mol.

Question

The value of ΔG° at 25 °C for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s,rhombic)+ 3O₂ (g)→ 2SO₃ (g) Is ________ kJ/mol.

Quizplus · Accepted Answer

To determine ΔG°, we can use the equation ΔG° = -nFE°, where n is the number of electrons transferred, F is the Faraday constant, and E° is the standard reduction potential. 
First, we need to find the half-reactions and their reduction potentials:

S (s) → S2- (aq) + 2e-           E°red = -0.24 V

SO3 2- (aq) + H2O (l) + 2e- → HSO4 - (aq) + OH- (aq)          E°red = +0.17 V

The oxidation half-reaction is multiplied by 3 to balance the electrons:

3S (s) → 3S2- (aq) + 6e-

Next, we can write the overall reaction as the sum of the two half-reactions:

3S (s) + 2SO3 2- (aq) + 2H2O (l) → 3S2- (aq) + 2HSO4 - (aq) + 2OH- (aq)

The number of electrons transferred is 6, so n = 6.

Now we can calculate E°cell:

E°cell = E°reduction - E°oxidation 
E°cell = (+0.17 V) - (-0.24 V) 
E°cell = +0.41 V

Finally, we can use the equation ΔG° = -nFE° to find ΔG°:

ΔG° = -nFE° 
ΔG° = -(6 mol)(96,485 C/mol)(+0.41 V) 
ΔG° = -740.8 kJ/mol

Therefore, the answer is D, -740.8 kJ/mol.

The Value of ΔG° at 25 °C for the Oxidation