Edexcel A-Level Chemistry: Physical and Inorganic II (Topics 12-17) overview

What this block demands

Topics 12 to 17 are the calculation core of the second year. They cover why reactions are feasible, how electron transfer can be quantified, the distinctive chemistry of the transition metals, the mathematics of rate, the quantitative treatment of equilibrium, and the control of acidity. The examiners test confident, well-laid-out calculations with correct units and the ability to distinguish feasibility from rate.

This guide walks through the six topics in specification order and sets out the exam patterns Edexcel repeats. Each topic has a matching dot-point page with practice questions.

Thermodynamics and electrode potentials

Topic 12 (Thermodynamics) adds Born-Haber cycles and lattice energy, enthalpies of solution and hydration, entropy, and the decisive idea of Gibbs free energy, $\Delta G = \Delta H - T\Delta S$. A reaction is feasible when $\Delta G \leq 0$, which lets you find the temperature at which it becomes spontaneous.

Topic 13 (Redox II) covers standard electrode potentials, the standard hydrogen electrode, cell EMF, the prediction of feasibility from electrode potentials, and redox titrations such as manganate(VII) against iron(II). A positive EMF means feasible, not necessarily fast.

Transition metals

Topic 14 (Transition metals) explains variable oxidation states, complex ions and ligands, the origin of colour (d-orbital splitting and absorption of visible light), catalysis (homogeneous via variable oxidation states, heterogeneous via adsorption), and ligand substitution. Remember that scandium and zinc are not transition metals.

Rate, equilibrium and acids

Topic 15 (Kinetics II) turns rate into mathematics: $\text{rate} = k[A]^m[B]^n$, orders found only by experiment, the rate constant, the rate-determining step, and the Arrhenius equation. Topic 16 (Equilibrium II) covers $K_c$ and $K_p$ calculations, mole fractions and partial pressures. Topic 17 (Acid-base equilibria) closes with the Bronsted-Lowry definitions, the pH scale, $K_a$ and $K_w$, titration curves, indicator choice and buffer action.

How this block is examined

A typical Edexcel profile for Topics 12 to 17:

• Calculations. Born-Haber cycles, Gibbs free energy and feasibility temperature, cell EMF and redox titrations, orders and the rate constant, $K_c$ and $K_p$ with units, and pH, $K_a$ and $K_w$ work.
• Explanations. Lattice and hydration enthalpy trends, why a feasible reaction can be slow, transition-metal colour and catalysis.
• Data questions. Interpreting rate-concentration data, titration curves and electrode-potential tables.
• Extended answers. Born-Haber reasoning, buffer action, and ligand substitution.

Check your knowledge

A mix of recall and calculation questions across Topics 12 to 17. Attempt them under timed conditions, then check against the solutions.

1. A reaction has $\Delta H = +30\ \text{kJ mol}^{-1}$ and $\Delta S = +120\ \text{J K}^{-1}\text{mol}^{-1}$. Find the temperature above which it is feasible. (3 marks)
2. Two half-cells have $E^\ominus$ values of $+0.80\ \text{V}$ and $-0.44\ \text{V}$. Calculate the cell EMF. (2 marks)
3. Explain why aqueous copper(II) ions are coloured. (3 marks)
4. A reaction obeys $\text{rate} = k[A][B]^2$. State the overall order and the effect of doubling $[B]$. (2 marks)
5. For $H_2 + I_2 \rightleftharpoons 2HI$, $[H_2] = 0.20$, $[I_2] = 0.20$, $[HI] = 1.60\ \text{mol dm}^{-3}$. Calculate $K_c$. (2 marks)
6. Calculate the pH of $0.050\ \text{mol dm}^{-3}$ hydrochloric acid. (2 marks)