Question

Calculate the Gibbs free energy change at 1200°C for the following reaction:

MgS (s) + 3/2 O2 (g) → SO2 (g) + MgO (s)

Answer 1

Reaction

MgS(s) + (3/2)O2(g) -----------> SO2(g) + MgO(s)

Now we will first write the standard heat of formation

Hf for MgS(s) = 145.23 KJ/mol

Hf for O2 = 0 KJ/mol

Hf for SO2(g) = - 296.1 KJ/mol

Hf for MgO(s) = -601.24 KJ/mol

Now we will calculate the standard entropy

S for MgS(s) = 225.49 KJ/mol

S for O2 = 205.21 J/mol

S for SO2(g) = +248.21 J/mol

S for MgO(s) =+26..85 J/mol

Now gibbs energy of reaction is defined as

T = 1200 oC = 1200+273.15 = 1473.15 oC