240 cm³ of ethane (C₂H₆) was burnt in a controlled way and found to raise the temperature of 100 cm³ of water by 33.5 °C. (specific heat capacity of water = 4.18Jg^–1K^–1; 1mol of gas molecules occupies 24.0 dm³ at r.t.p.)

a. How many moles of ethane were burnt?

b. Calculate the heat change for the experiment.

c. Calculate the molar enthalpy change of combustion for ethane, as measured by this experiment.

d. Use the values below to calculate the standard molar enthalpy change for the complete combustion of ethane.

ΔH^Q_f[CO2] = –394 kJ mol^–1

ΔH^Q_f[H2O] = –286 kJ mol^–1

ΔH^Q_f[C2H6] = –85 kJ mol^–1

e. Give possible reasons for the discrepancy between the two results.