For the combustion of methane at 298 K, CH (g) + 2 O (g) → CO (g) + 2 H O(l)

CHEMISTRY · Subjective · A Level · Chemistry · Energetics · Energetics

Problem

For the combustion of methane at 298 K, CH4_4(g) + 2 O2_2(g) → CO2_2(g) + 2 H2_2O(l), complete the tasks below. • Using the standard enthalpies of formation ΔHf∘_f^{\circ}(CH4_4, g) = –74.8 kJ mol–1^{–1} ΔHf∘_f^{\circ}(CO2_2, g) = –393.5 kJ mol–1^{–1} ΔHf∘_f^{\circ}(H2_2O, l) = –285.8 kJ mol–1^{–1}, calculate ΔH298∘\Delta H^{\circ}_{298} for the reaction. • An alternative route proceeds through the sequence 1. CH4_4(g) → C(graphite) + 2 H2_2(g) ΔH∘^{\circ} = +74.9 kJ 2. C(graphite) + O2_2(g) → CO2_2(g) ΔH∘^{\circ} = –393.5 kJ 3. 2 H2_2(g) + O2_2(g) → 2 H2_2O(l) ΔH∘^{\circ} = –571.6 kJ Sum these steps to obtain a second value of ΔH298∘\Delta H^{\circ}_{298}. Do the two values agree within 1 kJ? Provide both numerical results and your conclusion.

Related theory

Browse the problem library