The heat combustion of acetylene, C₂H₂(g), at 25°C, is -1299 kJ/mol. At this temperature, ΔH°_f values for CO₂(g) and H₂O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔH°_f for acetylene.

Question

Quizplus · Accepted Answer

The combustion reaction for acetylene is: 2C₂H₂(g) + 5O₂(g) → 4CO₂(g) + 2H₂O(l). Using ΔH° = ΣΔH°f(products) - ΣΔH°f(reactants), we have: -1299 kJ/mol = [4(-393) + 2(-286)] - [2(ΔH°f(C₂H₂))]. Solving for ΔH°f(C₂H₂), we get 227 kJ/mol.

The Heat Combustion of Acetylene, C2H2(g), at 25°C, Is -1299

The Heat Combustion of Acetylene, C₂H₂(g), at 25°C, Is -1299