Relative Atomic Mass
Ar = weighted average mass of one atom relative to 1/12 the mass of a carbon-12 atom. No units.
Cambridge O Level 5070
🧪 O Level Chemistry Formula Sheet 2026
Key equations and relationships for Cambridge O Level Chemistry (5070) — stoichiometry, rates, energetics, electrochemistry and organic chemistry.
Stoichiometry Rates Energetics Electrochemistry Organic
Our formula sheets are free to download — save this one as PDF for offline revision.
Aligned with the latest 2026 syllabus and board specifications. This sheet is prepared to match your exam board’s official specifications for the 2026 exam series.
All O Level Chemistry Formulas and Key Relationships
Cambridge O Level Chemistry (5070) requires precise use of formulas and chemical equations. This reference sheet covers all quantitative relationships from the syllabus, with notes on units and common errors that cost marks in Paper 2.
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Stoichiometry and mole calculations
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Rates, energetics and equilibrium
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Electrochemistry and electrolysis
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Organic chemistry quick reference
Atomic Structure and the Mole
Moles
n = moles (mol), m = mass (g), Mr = relative molecular/formula mass (g/mol)
n = m / Mr Moles from Volume of Gas (RTP)
At room temperature and pressure (RTP), 1 mole of any gas = 24 dm³ (24 000 cm³). V in dm³.
n = V / 24 Moles from Concentration
n = moles (mol), c = concentration (mol/dm³), V = volume (dm³). Convert cm³ to dm³ first (÷ 1000).
n = c × V Concentration
c = concentration (mol/dm³), n = moles (mol), V = volume (dm³)
c = n / V Percentage Yield
Both yields in same units (g or mol).
% yield = (actual yield / theoretical yield) × 100% Percentage Purity
% purity = (mass of pure substance / total mass of sample) × 100% Empirical Formula
Divide masses by Ar → divide by smallest → find whole number ratio → write formula.
Chemical Energetics
Enthalpy Change
m = mass of solution (g), c = specific heat capacity (4.18 J/g°C for water), ΔT = temperature change (°C). Negative ΔH = exothermic.
ΔH = mcΔT Bond Energy Calculation
Energy input to break bonds − energy released forming bonds. All values in kJ/mol.
ΔH = Σ(bonds broken) − Σ(bonds formed) Hess's Law
Enthalpy change of a reaction is independent of the route taken. ΔH = ΔH₁ + ΔH₂ + ... (or use energy cycle diagrams).
Rates of Reaction
Rate of Reaction
Units: mol/s, g/s, cm³/s depending on what is measured.
Rate = amount of reactant used (or product formed) / time Factors Affecting Rate
Concentration ↑ → rate ↑ (more frequent collisions). Temperature ↑ → rate ↑ (more energetic collisions, more exceed activation energy). Surface area ↑ → rate ↑. Catalyst → lowers activation energy → rate ↑.
Electrochemistry
Electrolysis — Charge
Q = charge (C), I = current (A), t = time (s)
Q = It Mass Deposited (Faraday)
M = molar mass (g/mol), n = number of electrons transferred per ion, F = Faraday constant (96 500 C/mol)
m = (M × I × t) / (n × F) Electrode Products
At cathode (negative): cations discharged (metal deposits or H₂ released). At anode (positive): anions discharged (O₂ or halogen gas released). With active anode: metal dissolves.
Organic Chemistry Quick Reference
General Formulae
Alkanes (CₙH₂ₙ₊₂)
Alkenes (CₙH₂ₙ)
Alcohols (CₙH₂ₙ₊₁OH)
Carboxylic acids (CₙH₂ₙ₊₁COOH)
Esterification
Reversible reaction. Catalyst: concentrated H₂SO₄. Product named: [alkyl] [carboxylate].
Alcohol + Carboxylic acid ⇌ Ester + Water Combustion
Balance carefully: carbon → CO₂, hydrogen → H₂O.
CₙH₂ₙ₊₂ + O₂ → CO₂ + H₂O (complete combustion) Acids, Bases and Salts
pH Scale
pH < 7 = acidic, pH 7 = neutral, pH > 7 = alkaline. Each unit = 10× change in H⁺ concentration.
Neutralisation
Moles of acid × its concentration = moles of base × its concentration (at equivalence point).
Acid + Base → Salt + Water Titration Calculation
n₁ and n₂ are the mole ratios from the balanced equation.
c₁V₁ / n₁ = c₂V₂ / n₂ How to Use This Formula Sheet
Boost your Cambridge exam confidence with these proven study strategies from our tutoring experts.
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Mole calculations: show every step
Write formula → substitute → calculate. In O Level Chemistry Paper 2, each step can earn a mark.
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Exothermic vs endothermic
Exothermic: temperature rises, ΔH is negative. Endothermic: temperature falls, ΔH is positive. Learn to read energy profile diagrams.
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Electrolysis electrode rules
Always state which electrode (cathode/anode) and which ion is being discharged. Half-equations earn marks in Paper 2.
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Organic: name + draw + react
For each organic compound: know the name, structural formula, and key reactions (combustion, addition, esterification).
Formula Sheet FAQ
Quick answers about this free PDF and how to use it for exam revision and active recall.
Is the Cambridge O Level Chemistry Formula Sheet 2026 free to download as a PDF?
Yes. This Tutopiya formula sheet is free to use and you can download it as a PDF from this page for offline revision. There is no payment or account required for the PDF download.
What Chemistry topics and equations does this formula sheet cover?
This page groups key Chemistry formulas in one place for revision. Complete formula reference for Cambridge O Level Chemistry (5070). Key equations for stoichiometry, rates, energetics, electrochemistry and organic chemistry with O Level exam tips. Always cross-check with your official syllabus and past papers for your exam session.
Can I use this instead of the official exam formula booklet in the exam?
No. In the exam you must follow only what your exam board allows in the hall—usually the official formula booklet or data sheet where provided. This page is a revision and teaching aid, not a replacement for board-issued materials.
Who is this formula sheet for (Secondary)?
It is written for students preparing for assessments at Secondary in Chemistry, including classroom revision, homework support, and independent study. Teachers and tutors can also share it as a quick reference.
How should I revise with this formula sheet?
Work through past paper questions, quote the correct formula before substituting values, and check units and notation every time. Pair this sheet with timed practice and mark schemes so you see how examiners expect working to be set out.
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This formula sheet aligns with Cambridge O Level Chemistry (5070) syllabus content.
Always balance chemical equations fully. The Faraday constant (96 500 C/mol) is typically provided in the exam paper.