(a) (i) Identify the processes represented by A, B and D in the cycle.

(a) (ii) Define the enthalpy change, F.

(a) (iii) Determine the value of the enthalpy change, E.

(a) (iv) Define the enthalpy change C for the first value. Explain why the second value is significantly larger than the first.

(a) (v) The inter-ionic distance between the ions in NaF is very similar to that between the ions in MgO. Suggest with a reason, which compound has the higher lattice enthalpy value.

(b) (i) The standard enthalpy change of three combustion reactions is given below in kJ.

• 2C₂H₆(g)+7O₂(g)→  4CO₂(g)+6H₂O(l)           ΔH^Θ=−31202
• H₂(g)+O₂(g)→  2H₂O(l)                                 ΔH^Θ=−572
• C₂H₄(g)+3O₂(g)→  2CO₂(g)+2H₂O(l)           ΔH^Θ=−1411

Based on the above information, calculate the standard change in enthalpy, ΔH^Θ, for the following reaction.

(b) (ii) Predict, stating a reason, whether the sign of ΔS^Θ for the above reaction would be positive or negative.