OCR A-level Chemistry (H432): papers, marks and grade boundaries

OCR A-level Chemistry at a glance

OCR offers two A-level chemistry courses: Chemistry A (H432) and Chemistry B, Salters (H433). This guide covers Chemistry A, which is the one most schools teach. It is regulated in England, assessed entirely by written papers at the end of the two years, and sat in a single May and June series. All three papers must be taken in the same series.

The marks add up to 270. Every paper includes synoptic assessment, extended response questions and stretch and challenge questions, which are there to separate A from A*. The practical endorsement does not change your grade: it is a separate pass, based on a minimum of 12 assessed practical activities.

What each paper looks like

Paper 1: Periodic table, elements and physical chemistry

Section A is 15 multiple choice marks and Section B is 85 marks of structured questions, calculations, practical questions and extended response. It examines modules 1, 2, 3 and 5: practical skills, foundations in chemistry (atoms, amount of substance, acids and redox, bonding), the periodic table and energy (Group 2, the halogens, enthalpy, rates and equilibrium), and physical chemistry and transition elements (rate equations, Kc and Kp, pH and buffers, entropy, electrode potentials).

Paper 2: Synthesis and analytical techniques

The same layout: 15 marks of multiple choice, then 85 marks of written questions. It examines modules 1, 2, 4 and 6: core organic chemistry (alkanes, alkenes, alcohols, haloalkanes, infrared and mass spectra) and organic chemistry and analysis (aromatics, carbonyls, carboxylic acids, amines, polymers, chromatography and NMR).

Paper 3: Unified chemistry

One 70 mark paper with no multiple choice section, made of short answer, calculation, practical and extended response questions that can draw on all six modules. Expect questions that join topics together, such as an unfamiliar compound that needs spectra, a titration and a mechanism.

Calculator, data sheet and what you must learn

OCR allows a scientific or graphical calculator in components 01, 02 and 03, subject to the JCQ rules. OCR also publishes a Chemistry A data sheet in the specification, covering constants such as the molar gas volume of 24.0 dm³ mol⁻¹ at room temperature and pressure. You still need to learn definitions such as the enthalpy terms and standard electrode potential, and the rules for working out orders of reaction.

Worked examples in OCR style

Amount of substance: a titration

25.0 cm³ of 0.100 mol dm⁻³ sodium hydroxide is neutralised by 21.40 cm³ of sulfuric acid. Find the concentration of the acid.

The equation is 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O, so the acid is half as many moles:

Give the answer to 3 significant figures, as the data does. Showing the mole ratio line is worth a mark on its own in OCR mark schemes.

Rates: finding a rate equation

Compare experiments 1 and 2: [A] is doubled and the rate is doubled, which gives order 1 in A. Compare 1 and 3: [B] is doubled but the rate rises by a factor of 4, which gives order 2 in B. Putting the orders together:

The units come from dividing mol dm⁻³ s⁻¹ by (mol dm⁻³)³. They are usually a mark of their own. Practise more of these in our Reaction Kinetics course:

Energy: a calorimetry experiment

Burning 0.46 g of ethanol (M = 46.0 g mol⁻¹) warms 100 g of water by 13.5 K. Use c = 4.18 J g⁻¹ K⁻¹.

The data book value is far more exothermic, about −1367 kJ mol⁻¹. The usual evaluation points are heat lost to the surroundings and the air, incomplete combustion, and heat absorbed by the can. Say which direction the error goes: the experiment gives a less negative value than the true one.

Practical skills in the written papers

Module 1 is not examined in a separate paper. Around the course, questions on planning, measurement, uncertainty, titrations, distillation, reflux, qualitative tests and chromatography appear in all three papers, so the required practical work matters even though the endorsement itself is not graded.

Grades and June 2026 grade boundaries

Your grade comes from the total out of 270, not from separate paper grades. OCR adds your three raw marks and compares the total with the boundaries for that series. The table is from OCR’s boundaries document published on 14 September 2026 and shows the June 2026 series. Boundaries change each year with the difficulty of the papers, so use them as a guide only.

Worked through: scoring 70, 66 and 44 gives 180 out of 270, which is above the grade B boundary of 164 and below the A boundary of 200. Reaching A* needs 234, about 87% of all the marks.

Using the daily paper as a short timed mock

Uni-Sine publishes a free daily paper for each A-level chemistry track, and a new one every day. Each is a short timed paper of 8 questions worth 25 to 35 marks, marked instantly with worked answers. It is not a full OCR paper and OCR does not write it. Sit it with a timer and a calculator, then use it as a quick mock between full past papers.

• Chemistry Advanced 1 covers amount of substance, enthalpy changes and Hess’s law, redox, bonding and shapes, kinetics and the Maxwell-Boltzmann distribution, equilibria, periodicity and Group chemistry, alcohols, alkanes, alkenes and halogenoalkanes. That lines up with Paper 1 and the early organic work in Paper 2.
• Chemistry Advanced 2 covers acids, bases and buffers, rate equations, Kp, Born-Haber cycles and entropy, electrode potentials, transition metals, aromatic chemistry, carbonyls, amines and polymers, NMR and organic synthesis, which are modules 5 and 6.
• A daily paper is much shorter than a real one, so it does not replace full papers for timing, extended response and synoptic work. For general advice on running mocks, see our A-level mocks guide and the broader A-level Chemistry guide.

A weekly rhythm that works: one daily paper per paper-style, a careful look at every dropped mark, and a full 2 hours 15 minute past paper from OCR’s own site once a fortnight in the run-up to May.

Taking the WJEC Eduqas course instead? Read our Eduqas A-level Chemistry guide, which has its own papers and boundaries.

Exam answers

Uni-Sine does not publish official answers or mark schemes for OCR A-level Chemistry papers. The answers and a worked mark scheme for each question come with today’s paper once you have submitted it and it has been marked, so you can see where every mark was won or lost.

Common mistakes in OCR A-level Chemistry

• Missing units on rate constants. Work them out every time from the rate equation.
• Rounding too early. Carry the full calculator value through a multi-step calculation and round only at the end.
• Writing mechanisms with loose curly arrows. An arrow starts at a lone pair or bond and ends at an atom or bond.
• Defining enthalpy terms loosely. State the conditions: standard states, 1 mol, 100 kPa and a stated temperature.
• Leaving extended response answers unstructured. Level of response marking rewards a clear, linked chain of reasoning.

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UK · A-levelOCR A-level Chemistry grade boundaries 2026: A* to EOCR A-level Chemistry June 2026 boundaries for Chemistry A (H432) and Salters B (H433), paper by paper, plus AS, with three years compared.