Question

HQ5.49 Use standard enthalpies of formation to calculate the standard enthalpy of reaction for the following reaction: 2 H 2 ​ S(g) + 3 O 2 ​ (g) → 2 H 2 ​ O(l) + 2 SO 2 ​ (g) ΔH ∘ rxn ​

Answer 1

Answer is: the standard enthalpy of reaction is -1124,2 kJ/mol.
ΔHf(H₂S) = -20.5 kJ/mol
ΔHf(O₂)=0 kJ/mol.
ΔHf(H₂O) = -285.8 kJ/mol.
ΔHf(SO₂) = -296.8 kJ/mol.
ΔHrxn = ∑ΔHf (products of reaction) - ∑ΔHf (reactants).
ΔHrxn - enthalpy change of chemical reaction.
ΔHf - enthalpy of formation of reactants or products.
ΔHrxn = (2 · (-285,8) + 2 · (-296,8)) - (2 · (-20,5)) · kJ/mol.
ΔHrxn = -1124,2 kJ/mol.