A 0.1 M solution of weak acid HA has a pH of 4.70 at 25.0°C.

ii) Calculate the standard free energy change (ΔG°) for the acid dissociation at 25.0°C. ΔG° = kJ mol^-1 at 25 °C. [1 mark]

iii) At 75.0°C, the value of ΔG° is +66.0 kJ mol^-1.  Calculate the entropy change (ΔS°) for the acid dissociation, assuming that both the enthalpy and entropy changes (ΔH° and ΔS°, respectively) are constant over the temperature range considered.

The entropy change is J K^-1 mol^-1 [2 marks]