What is the heat of combustion of ethane, C2H6 in kilojoules per mole of ethane? Enthalpy of formation values can be found in this . Δ𝐻∘rxn = ________ kJ/mol ethane

Question

What is the heat of combustion of ethane, C₂H₆ in kilojoules per mole of ethane? Enthalpy of formation values can be found in this .

Δ𝐻∘rxn = ________ kJ/mol ethane

Answer 1

1) Write the combustion reaction and balance: C₂H₆ + 7/2 O₂ ⇒ 2CO₂(g) + 3H₂O(g) You have to specify that the water is in vapor form (usually the case in a combustion process). We are going to use the ΔH_f at 25 degrees C, but ΔH_rxn are assumed to not change much with T.

2) The ΔH_c = 2ΔH_f,CO2 + 3ΔH_f,H2O - ΔH_f,C2H6 This will be negative, because combustion is exothermic. You will have to look up the Heats of Formation in the appendix at the back of your text (Should be in kJ/mole, but check)