OCR GCSE Chemistry (J248 Gateway Science): papers, marks and grade boundaries

OCR GCSE Chemistry at a glance

OCR has two GCSE chemistry specifications: Chemistry A (Gateway Science, J248) and Chemistry B (Twenty First Century Science, J258). This guide covers Chemistry A. It is linear, with all papers sat in the May and June series at the end of the course, and you are entered for Foundation or Higher tier.

Foundation entries can reach grades 5 to 1, Higher entries 9 to 4. Papers 2 and 4 mix in some synoptic questions and rely on what you learned in C1 to C3.

What the papers cover

• C1 Particles: the particle model and atomic structure.
• C2 Elements, compounds and mixtures: purity and separating mixtures, bonding and the properties of materials.
• C3 Chemical reactions: introducing chemical reactions, energetics, types of reaction and electrolysis.
• C4 Predicting and identifying reactions and products: predicting reactions from the periodic table and identifying products.
• C5 Monitoring and controlling chemical reactions: rates, controlling reactions and equilibria.
• C6 Global challenges: improving processes and products, organic chemistry and interpreting earth systems.
• C7 Practical skills: the practical activities, worth 15% of the marks, tested in both papers.

Every paper starts with 15 multiple choice marks, followed by 75 marks of written work, which includes one six mark level of response question. The specification expects you to use a supplied periodic table to write formulae and balanced equations, so you never have to memorise relative atomic masses.

Calculator and maths in OCR GCSE Chemistry

OCR permits a scientific or graphical calculator in all four papers, subject to the JCQ rules. Typical calculations use relative formula mass, moles, reacting masses, concentration, rates and percentage yield. Always show the formula, the substitution and the units.

Worked examples in OCR style

Reacting masses

What mass of magnesium oxide forms when 6.0 g of magnesium burns in oxygen? The equation is 2Mg + O₂ → 2MgO. Use Mg = 24 and O = 16.

The ratio of Mg to MgO is 2 : 2, so 0.25 mol of MgO forms. Its relative formula mass is 24 + 16 = 40.

The mass increases from 6.0 g to 10 g because the oxygen from the air joins the magnesium. Practise related skills in our Atomic Structure course:

Concentration

5.3 g of sodium carbonate (Mr 106) is dissolved to make 250 cm³ of solution. The amount is 5.3 ÷ 106 = 0.050 mol, and 250 cm³ is 0.25 dm³:

Rates and yield

If a reaction makes 48 cm³ of gas in 60 seconds, the mean rate is 48 ÷ 60 = 0.80 cm³/s. For yield, if 7.2 g of a product is made and the maximum possible is 9.0 g, the percentage yield is:

Extended response

For a six mark question such as comparing the properties of ionic and covalent compounds, write about structure, bonding and the property in a linked way, such as "ionic compounds conduct when molten because the ions are free to move". A list of unlinked facts earns fewer marks.

Grades and June 2026 grade boundaries

OCR adds your two paper marks into a total out of 180 and compares it with the boundaries for your tier. These tables are from OCR’s document published on 25 September 2026 for the June 2026 series. They change every year.

Higher tier boundaries

Foundation tier boundaries

Worked through: a Higher student with 78 and 66 marks has 144 out of 180, which is above the grade 7 boundary of 139 and below the grade 8 boundary of 151, so it is a grade 7.

Using the daily paper as a short timed mock

Free daily papers run on both the Chemistry Foundation and Chemistry Higher tracks, refreshed every day: 8 questions, 25 to 35 marks, marked on submission. They are not OCR papers and are far shorter than a real one, which makes them handy for a drill on moles or bonding.

• Foundation covers: the periodic table, rates of reaction, states of matter, atomic structure, ionic and covalent bonding, crude oil and fuels, acids, alkalis and salts, the atmosphere and separating mixtures.
• Higher covers: atomic structure and isotopes, energy changes, organic chemistry, moles and reacting masses, chemical analysis, electrolysis, bonding, concentration and titration, rates and collision theory, and reversible reactions.

For more on mocks, see our GCSE mocks guide, the GCSE Chemistry guide and the GCSE Chemistry mock paper page.

Exam answers

Uni-Sine does not publish official answers or mark schemes for OCR GCSE 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 GCSE Chemistry

• Unbalanced equations. Check the atom count on each side before reading off a mole ratio.
• A wrong Mr. Brackets and subscripts change the total, so add every atom.
• Confusing cm³ and dm³. Divide by 1000 to convert cm³ to dm³.
• Saying "ionic bonds conduct" without the condition: they conduct only when molten or dissolved.
• Missing the context of an extended response, such as the particular substances named in the question.

Read next

UK · GCSEOCR GCSE Chemistry grade boundaries 2025: all gradesOCR GCSE Chemistry grade boundaries for June 2025: Gateway A and Twenty First Century B, Higher and Foundation, with 2024 for comparison.