NCEA Level 3 Chemistry: the three externals, the exam and practice

NCEA Level 3 Chemistry standards

That is 15 external credits and up to 13 internal credits. NZQA's past exams and assessment schedules are on its Chemistry past exams page.

The NCEA Level 3 Chemistry exam

NZQA's 2027 assessment specifications say the exam is on printed paper, questions may use unfamiliar contexts, and any context-specific formulae are given. Show all working, give answers to an appropriate number of significant figures (usually three) with units, and use the molar masses supplied.

What each external covers

Thermochemistry and particles (91390)

Electron configurations of the first 36 elements using s, p and d notation; periodic trends in atomic radius, ionisation energy and electronegativity; Lewis structures, shapes with up to six electron pairs and polarity; attractive forces between particles, including hydrogen bonding; and thermochemical principles such as specific heat capacity, phase changes and enthalpy changes of combustion, formation, reaction, vaporisation, sublimation and fusion.

Organic compounds (91391)

Compounds with alkene, haloalkane, amine, alcohol, aldehyde, ketone, carboxylic acid, ester (including triglycerides), acyl chloride and amide groups; constitutional isomers and stereoisomers; substitution, addition, elimination, oxidation and other reactions with specified reagents; and physical properties, including rotation of plane-polarised light.

Equilibrium in aqueous systems (91392)

Sparingly soluble ionic solids and their solubility product Ks, the common ion effect, complex ions and predicting precipitation; and acidic and basic solutions of monoprotic acids, bases, salts and buffers, including pH calculations and titration curves.

Worked examples

Aqueous equilibrium: solubility from Ks

Silver chloride has Ks = 1.8 × 10⁻¹⁰ at 25 °C. For an AB salt, Ks = s², so its solubility in water is:

Aqueous equilibrium: pH of a weak acid

Find the pH of 0.010 mol L⁻¹ ethanoic acid, Ka = 1.74 × 10⁻⁵. Assuming little of the acid ionises, [H₃O⁺] = √(Ka × c) = √(1.74 × 10⁻⁷) = 4.17 × 10⁻⁴ mol L⁻¹, so the pH is 3.38.

Thermochemistry: heating water

Heating 200 g of water by 15.0 °C needs q = mcΔT = 200 × 4.18 × 15.0 = 12,540 J, or 12.5 kJ.

Practise recognising functional groups in our Organic Chemistry course, then press Mark to check your answer in the course:

Grades, credits and endorsements

Every NCEA standard is graded Not Achieved, Achieved, Merit or Excellence, and earns its credits at whatever grade you reach. Achieved shows you meet the standard, Merit shows deeper understanding, and Excellence shows it applied to harder, unfamiliar problems.

• The certificate: NCEA Level 3 needs 60 credits at Level 3 or above, plus the 20-credit literacy and numeracy co-requisite, which you can gain any time before you leave school. Since 2024 you can no longer carry 20 credits over from the level below.
• Certificate endorsement: 50 credits at Merit or better gives a Merit endorsement; 50 at Excellence gives an Excellence endorsement.
• Course endorsement: 14 or more credits at Merit or Excellence in one subject in one year, with at least 3 from internal and 3 from external standards in most subjects.

Use the daily paper as a practice exam

Uni-Sine publishes a free daily paper on the NCEA Level 3 Chemistry track. It is a short timed paper: 8 questions worth 25 to 35 marks, marked instantly, with worked answers. It is not a full NCEA exam and it is not written by NZQA, so treat it as a quick daily practice test alongside NZQA's past papers.

• What it covers well: acids, bases and buffers, carbonyl compounds, amines and polymers, organic synthesis and lattice enthalpies, which support 91392, 91391 and parts of 91390.
• What it does not cover: solubility products and the common ion effect, electron configuration and periodic trends, specific heat capacity, and the internals. It also includes transition metals, electrode potentials, entropy, rate equations, Kp and NMR, which are not NCEA Level 3 externals.

A good routine is one daily paper under timed conditions, then a careful look at every mark you dropped, then one NZQA past paper a week in the weeks before the exam.

NCEA changes for 2026, 2027 and beyond

NCEA still applies in 2026 and 2027, so the standards on this page are the ones you will sit. New Level 3 standards are due to be fully in place by 2029, and in 2030 a new New Zealand Advanced Certificate of Education (NZACE) replaces NCEA Level 3 for Year 13. The Government agreed the structure of the new qualification system on 26 March 2026, and the Ministry of Education confirmed further details and the timeline on 16 May 2026.

Common mistakes in NCEA Level 3 Chemistry

• Using the strong-acid shortcut for a weak acid. Weak acids need Ka; [H₃O⁺] is not equal to the acid concentration.
• Forgetting the common ion. A salt is less soluble in a solution that already contains one of its ions.
• Confusing structural isomers and stereoisomers. Optical isomers need a chiral carbon with four different groups.
• Missing the link to particles. Explain properties such as boiling point by the forces between particles, not just by naming them.

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