Unit 3: Equilibrium, Acids and Bases, and Redox

Conjugate acid-base pairs, how they differ by one proton, the inverse strength relationship, and amphiprotic species, with a worked example and common exam mistakes.

Acid-base indicators, how they behave as weak acid equilibria, their colour change range, and how to choose an indicator matched to a titration equivalence point, with a worked example and common exam mistakes.

Corrosion, explaining rusting as an electrochemical process with anodic and cathodic regions, and evaluating prevention methods including sacrificial anodes and protective coatings, with a worked example and common exam mistakes.

Self-ionisation of water, defining the ionic product Kw, relating pH and pOH, and explaining the temperature dependence of Kw with a worked example and common exam mistakes.

Strong versus weak acids and bases, the acid and base ionisation constants Ka and Kb, the meaning of pKa, and how they quantify strength, with a worked example and common exam mistakes.

Dynamic equilibrium and Le Chatelier's principle, with worked predictions and the most common exam mistakes.

Electrolytic cells, how an external voltage drives non-spontaneous reactions, predicting products of molten and aqueous electrolysis, and industrial uses, with a worked example and common exam mistakes.

Polyprotic acids, their stepwise ionisation, why each successive Ka is smaller, and how this affects pH and titrations, with a worked example and common exam mistakes.

Galvanic cells, the roles of anode and cathode, electron and ion movement, the salt bridge, and cell notation, with a worked example and common exam mistakes.

Buffers, how a conjugate acid-base mixture resists pH change, with the equilibrium reasoning, a worked example and common exam mistakes.

Oxidation numbers and half-equations, how to assign oxidation states, identify oxidation and reduction, and balance half-equations including in acidic solution, with a worked example and common exam mistakes.

Standard electrode potentials, the reference hydrogen electrode, predicting spontaneity, and calculating standard cell EMF from the potential series, with a worked example and common exam mistakes.

Reaction quotient, how Q is calculated and compared with Kc to predict the direction of net reaction, with a worked example and common exam mistakes.

Quantitative electrolysis, using the relationships Q = It and Q = nF with the Faraday constant to calculate the amount of substance deposited or liberated at electrodes, with a worked example and common exam mistakes.

Bronsted-Lowry acids and bases, conjugate pairs, strong versus weak, Kw and pH calculations, with worked examples and common mistakes.

Volumetric analysis, the technique and calculations of acid-base titration, the shape of titration curves for different acid-base combinations, and the equivalence point, with a worked example and common exam mistakes.

Oxidation numbers, half-equations, galvanic and electrolytic cells and standard electrode potentials, with a worked cell-potential calculation and common mistakes.

Kc, the reaction quotient Q, and ICE-table calculations, with a fully worked numerical example and common errors.

Solubility equilibria, covering the solubility product Ksp, how it links to molar solubility, the common ion effect, and predicting precipitation with worked examples and common exam mistakes.