Question

1. Determine DH⁰_rxn for

S₈ (g)  + 12 O₂ (g) -> 8 SO₃ (g)

Given the following

DH_f⁰ ( O(g)) = 247.5 kJ/mole       DH_f⁰ ( O₂(g)) = 0 kJ/mole            DH_f⁰ ( O₃(g)) = 142.3  kJ/mole

DH_f⁰ ( S(rhombic)) = 0 kJ/mole   DH_f⁰ ( S₈(g)) = 102.3 kJ/mole      DH_f⁰ ( SO₃(g)) = -393.2 kJ/mole

Answer 1

Given:
Hof(S8(g)) = 102.3 KJ/mol
Hof(O2(g)) = 0.0 KJ/mol
Hof(SO3(g)) = -393.2 KJ/mol

Balanced chemical equation is:
S8(g) + 12 O2(g) ---> 8 SO3(g)

ΔHo rxn = 8*Hof(SO3(g)) - 1*Hof( S8(g)) - 12*Hof(O2(g))
ΔHo rxn = 8*(-393.2) - 1*(102.3) - 12*(0.0)
ΔHo rxn = -3247.9 KJ
Answer: -3247.9 KJ