Answer:
ΔH° = -1255.8 kJ
Explanation:
Step 1: Data given
ΔHf∘ C2H2 = 227.4 kJ/mol
ΔHf∘ O2 = 0 kJ/mol
ΔHf∘ CO2 = -393.5 kJ/mol
ΔHf∘ H2O = -241.8 kJ/mol
Step 2: The balanced equation
2C2H2(g)+5O2(g) ⟶ 4CO2(g)+2H2O(g)
C2H2(g)+5/2O2(g) ⟶ 2CO2(g)+H2O(g)
Step 3: Calculate ΔH° of the reaction
ΔH° = (2*ΔHf∘ CO2 + ΔHf∘ H2O) - (ΔHf∘ C2H2)
ΔH° = (2* -393.5 kJ/mol + (-241.8) kJ/mol) - 227.4 kJ/mol
ΔH° = -787 - 241.8 - 227. kJ/mol
ΔH° = -1255.8 kJ