The vapour pressures of water and ice at −10°C are 0.28 and 0.26 Pa, respectively. What is the free energy change for the process?
H₂O (l, −10°C, 0.28 Pa, 1 mole) → H₂O (s, −10°C, 0.26 Pa, 1 mole)

Question

The vapour pressures of water and ice at −10°C are 0.28 and 0.26 Pa, respectively. What is the free energy change for the process?

H₂O (l, −10°C, 0.28 Pa, 1 mole) → H₂O (s, −10°C, 0.26 Pa, 1 mole)

TestHub · Accepted Answer

Reversible path at −10°C (263 K): (i) l → g at 0.28 Pa, ΔG = 0 (equilibrium); (ii) vapour expands 0.28 → 0.26 Pa, ΔG = RT ln(0.26/0.28) = R × 263 × ln(13/14); (iii) g → s at 0.26 Pa, ΔG = 0. Total ΔG = R × 263 × ln(13/14). Matches (b).

Chemistry - Thermodynamics - II Question with Solution | TestHub

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