Entropy is a measure of the disorder of a system. Assume the entropy, S, for H₂O is zero at 0 K. The equation for a reaction that produces methanol is shown. CO2(g) + 3H2(g) → CH3OH(g) + H₂O(g) At 298 K, both products of this reaction are liquid. CO2(g) + 3H2(g) → CH3OH(l) + H₂O(l) ΔH° = -131 kJ mol⁻¹ Standard entropies are shown in the table. [Table: substance, S°/JK⁻¹mol⁻¹ for CO2(g), H2(g), CH3OH(l), H2O(l)] In a methanol-oxygen fuel cell, CH3OH(l) and O2(g) are in contact with two inert electrodes immersed in an acidic solution. The half-equation for the reaction at the methanol electrode is shown. CH3OH + H₂O ⇌ CO2 + 6H⁺ + 6e⁻ E° = -0.02 V

1. (a)Sketch a graph on the axes to show how the entropy changes for H₂O between 0 K and 300 K. [Graph axes: S/JK⁻¹ mol⁻¹ vs temperature/K from 0 to 300] [2][2]
2. (b)Place one tick (✔) in each row of the table to show the sign of the entropy changes, ΔS. | | ΔS is negative | ΔS is positive -----|----------------|-------------- solid dissolving in water | water boiling to steam | [1][1]
3. (c)Use relevant bond energies from the Data Booklet to calculate the enthalpy change, ΔH, for this gas phase reaction. ΔH = ...................................... kJ mol⁻¹ [2][2]
4. (d)(i)Calculate the standard entropy change, ΔS°, for this reaction. ΔS° = .............................................. JK⁻¹ mol⁻¹ [2][2]
5. (d)(ii)Calculate the standard Gibbs free energy change, ΔG°, for this reaction at 298 K. ΔG° = .............................................. kJ mol⁻¹ [2][2]
6. (d)(iii)Predict the effect of increasing the temperature on the feasibility of this reaction. [1][1]
7. (e)(i)Use the Data Booklet to write an equation for the overall cell reaction. [1][1]
8. (e)(ii)Use E° values to calculate the E°cell for this reaction. E°cell = ................................................ V [1][1]

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