Chemical thermodynamics and chemical equilibrium: every question, 2016 to 2025

Notes: Electrolytes: conductance, Kohlrausch, Debye–Hückel and transport numbers (full notes) · short notes

Notes: Second and third laws: entropy, Gibbs and Helmholtz energies, Maxwell relations (full notes) · short notes

Notes: Chemical potential, partial molar quantities, Gibbs–Duhem equation, fugacity and activity (full notes) · short notes

Notes: Chemical equilibrium: ΔG° and K, Kp, Kc and Kx, van ’t Hoff isochore and isobar (full notes) · short notes

Notes: First law of thermodynamics: work, heat, enthalpy, adiabatic changes, Joule–Thomson effect, thermochemistry (full notes) · short notes

Notes: Solutions: Raoult’s and Henry’s laws, colligative properties, van ’t Hoff factor and activity (full notes) · short notes

2025

• Q1(e) Fall of G with temperature at constant pressure5 marks Answered
• Q1(f) Z > 1 and f > P for the gas P(Vm − b) = RT5 marks Answered
• Q4 Chemical potential in terms of H and U10 marks Answered
• Q5 Debye–Hückel limiting law and the mean activity coefficient10 marks Answered
• Q11(a) Chemical potential of a real gas relative to an ideal gas5 marks Answered
• Q11(b) Kc from Kp for the dissociation of ammonia5 marks Answered
• Q11(c) van ’t Hoff isochore and a solution-phase dimerisation10 marks Answered

2024

• Q1(e) Chemical potential and its change with temperature5 marks Answered
• Q1(f) Relation between Kp, Kc and Kx5 marks Answered
• Q4 Equilibrium constant and standard Gibbs energy change10 marks Answered
• Q6 pH of an acetate buffer after adding NaOH10 marks Question only
• Q13(b) Activity as the thermodynamic counterpart of pressure10 marks Answered

2023

• Q1(e) Chemical potential and its link with Gibbs energy5 marks Answered
• Q1(f) Debye–Hückel limiting law for γ±5 marks Answered
• Q4 ΔG° and ΔS° from an equilibrium constant10 marks Answered
• Q12(a) Gibbs–Duhem equation15 marks Question only
• Q12(b) Ionic strength of a 3:2 electrolyte5 marks Question only

2022

• Q1(e) Reversal of HCl + NH₃ ⇌ NH₄Cl with temperature5 marks Answered
• Q1(f) ΔG for compressing a real gas, from fugacities5 marks Answered
• Q4 Variation of chemical potential with temperature and pressure10 marks Answered
• Q12(a) Change in pH of an acetate buffer on adding HCl10 marks Answered
• Q12(b) Activities of Na⁺ and SO₄²⁻ in a mixed electrolyte10 marks Answered
• Q13(b) Enthalpy of reaction when K doubles between 25 and 35 °C10 marks Answered

2021

• Q1(f) Activity and activity coefficient: units and magnitudes5 marks Answered
• Q4 Chemical potential in terms of G, A, H and U10 marks Answered
• Q12(a) Gibbs–Duhem equation Σ ni dȲi = 0 and its meaning10 marks Answered

2020

• Q1(d) Composition change and non-expansion work5 marks Answered
• Q1(e) Van't Hoff plots5 marks Answered
• Q4 Barium sulfate solubility product10 marks Answered
• Q12 Ammonium chloride dissociation thermodynamics20 marks Answered

2019

• Q1(e) Volume independence of ideal-gas heat capacity5 marks Answered
• Q1(f) Entropy on doubling volume5 marks Answered
• Q1(h) Ammonia buffer5 marks Answered
• Q1(i) Pure-component vapour pressures5 marks Answered
• Q3(b) Isotonic glucose concentration5 marks Answered
• Q5 Raising Carnot efficiency: hotter source or colder sink?10 marks Question only
• Q6(a) Pressure and equilibrium constant5 marks Answered
• Q7 Limits of pH and the pH scale at 25 °C10 marks Question only
• Q12(a) Work and efficiency of the stated cycle15 marks Answered
• Q13(a) Pressure dependence of mole-fraction equilibrium15 marks Answered

2018

• Q1(f) Gibbs and Helmholtz changes5 marks Answered
• Q1(g) Equilibrium-constant conventions5 marks Answered
• Q1(h) Very dilute hydrochloric acid5 marks Answered
• Q1(i) Pressure controlling boiling5 marks Answered
• Q3(a) Units in molar Gibbs energy5 marks Answered
• Q3(b) Equation of state from Gibbs energy5 marks Answered
• Q4 Entropy of equal-volume gas mixing10 marks Answered
• Q5 Molar mass from vapour-pressure lowering10 marks Answered
• Q11(a) Correct conditions for chemical equilibrium5 marks Question only
• Q15(a) Volume contraction on mixing5 marks Answered
• Q15(b) Entropy along two reversible paths15 marks Answered

2017

• Q1(b) Adiabatic expansion of helium6 marks Answered
• Q1(c) Arrhenius acids and bases6 marks Answered
• Q1(d) Carnot efficiency6 marks Answered
• Q1(e) Dimerization and temperature6 marks Answered
• Q1(g) Van't Hoff factor6 marks Answered
• Q2 Difference of heat capacities10 marks Answered
• Q3 Thermodynamics of vaporization10 marks Answered
• Q4 Gibbs–Duhem equation10 marks Answered
• Q5 Electrolyte dissociation from freezing points10 marks Answered
• Q7(b) pH of 10⁻⁸ M NaOH2 marks Question only
• Q11(a) Deriving the freezing-point depression ΔTf = Kf·m10 marks Question only
• Q11(b) Entropy signs for a cooling cup of tea10 marks Question only

2016

• Q1(e) Expansion cooling of helium5 marks Answered
• Q1(f) Temperature dependence of equilibrium5 marks Answered
• Q1(g) Ammonium chloride pH5 marks Answered
• Q1(h) Reverse osmosis5 marks Answered
• Q3 Chemical potential and Gibbs–Duhem equation10 marks Answered
• Q10(b) Reversible expansion of a real gas10 marks Answered