TCE Chemistry Level 4 (CHM415115) deep dive: criteria 5 to 8 for the 2026 exam

How this deep dive is organised

The TASC Chemistry Level 4 exam gives one rating for each of criteria 5 to 8, one section each. This guide follows the four criteria as the course document describes them and links every TCE Chemistry dot point on the site. Two site pages (buffers and solubility equilibria) go beyond the course document's list and are marked as background. For format and award rules, see the exam strategy guide.

Criterion 5: electrochemistry

Dot points: oxidation and reduction, balancing redox half-equations, electrochemistry, electrolysis and Faraday's laws, corrosion and its prevention.

• Oxidation states: assign them (including hydrogen in metal hydrides, $-1$, and oxygen in peroxides, $-1$), identify what is oxidised and reduced, and rank oxidisers and reducers with the electrochemical series.
• Half-equations in acidic solution: balance atoms, then O with $\text{H}_2\text{O}$, H with $\text{H}^+$, and charge with electrons.
• Galvanic cells: oxidation at the anode, reduction at the cathode, electrons through the external circuit from anode to cathode, the salt bridge maintaining electroneutrality, and cell diagrams with the anode on the left.
• Electrolytic cells: predict products for molten salts and aqueous solutions (inert or reactive electrodes), including electrorefining and electroplating.

Corrosion: iron is oxidised at anodic sites (often stressed areas or where oxygen is scarce), and oxygen is reduced at cathodic sites where its concentration is highest; dissolved ions speed up the process. Rust is ionic, brittle and occupies more volume than steel. Prevention: paint, oil, polymer and metal coatings (noble or sacrificial), and cathodic protection with sacrificial anodes or an applied EMF.

Criterion 6: thermochemistry, kinetics and equilibrium

Dot points: enthalpy and thermochemistry, Hess's law and bond energies, collision theory and reaction rates, catalysts and reaction rate, chemical equilibrium and Le Chatelier, equilibrium constant calculations, acids, bases and pH, weak acids and Ka. Background: buffer solutions, solubility equilibria and Ksp.

• Thermochemistry: bond breaking absorbs energy and bond forming releases it; draw enthalpy diagrams with activation energy; write thermochemical equations; use calorimetry, bond energies and Hess's law.
• Kinetics: average rate is change in amount or concentration over time; collision theory explains the effects of concentration, surface area, temperature, the nature of the reactants and catalysts. A Maxwell-Boltzmann style distribution shows that a small temperature rise greatly increases the fraction of particles with energy above the activation energy.
• Equilibrium: dynamic balance of forward and reverse rates; Le Chatelier's principle and its limitations; Kc calculations and the reaction quotient Q to predict direction.

Criterion 7: properties and reactions of organic and inorganic matter

Dot points: nomenclature and isomerism, organic families and reactions, reactions of alcohols, carboxylic acids and esters, polymers, analytical techniques, bonding and intermolecular forces.

• Organic reactions: substitution of alkanes with halogens; addition to alkenes and alkynes (including asymmetric reagents such as hydrogen halides and steam, which can give isomeric products); complete and incomplete combustion; oxidation of primary alcohols to aldehydes (copper catalyst or limited dichromate) and then to carboxylic acids (stronger oxidisers such as permanganate), secondary alcohols to ketones, tertiary alcohols not oxidised; esterification and ester hydrolysis (including alkaline); addition polymers and polyesters.
• Properties: hydrogen bonding raises boiling points of alcohols, amines and amides; polyalcohols boil much higher than simple alcohols; esters are insoluble and fragrant.
• Analysis: mass spectra (molecular ion and fragments), infrared bands for functional groups, and X-ray crystallography, often combined.
• Inorganic matter: gas properties and kinetic theory; the Bohr model; electron configurations with s, p and d subshells; ionisation energies; periodic trends in electronegativity, core charge, shielding, reactivity and atomic and ionic radii.

Criterion 8: quantitative problems

Dot points: stoichiometry and the mole, volumetric analysis calculations, acid-base titrations and curves, gas laws and molar volume, chemical synthesis.

The course document lists mass calculations, gravimetric analysis (precipitate mass, percentage purity and yield, water of crystallisation), primary standards and dilution, limiting reagents, acid-base and redox titrations, synthesis yield, and gas law calculations. It also states that calculations from criteria 5, 6 and 7 are examined here.

Common mistakes

Check your knowledge

1. What is the oxidation state of hydrogen in sodium hydride, NaH? (Answer: $-1$.)
2. Reversing a reaction with $\Delta H = -92$ kJ gives what enthalpy change? (Answer: $+92$ kJ.)
3. What is the molar volume of an ideal gas at SLC according to the information sheet? (Answer: 24.5 L mol$^{-1}$.)

Then try the criteria 5 to 8 quiz.