OCR A Level Chemistry A
OCR A Level Chemistry A Module 2: Foundations in Chemistry Exam Questions
Free OCR A Level Chemistry A exam questions for Module 2: Foundations in Chemistry, with a mark scheme for every pack. Covers atomic structure, isotopes, amount of substance, acids and titrations, redox and oxidation numbers, bonding, shapes and intermolecular forces.
Module 2: Foundations in Chemistry exam questions
4 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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A-Level Chemistry Flashcards for 2027 Onwards
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About OCR A Level Chemistry A Module 2: Foundations in Chemistry
Module 2 of OCR A Level Chemistry A lays the foundations for the whole course. It covers atoms, isotopes and relative masses, formulae and equations, amount of substance calculations, acids, bases and neutralisation, redox and oxidation numbers, electron configurations and the different types of bonding and structure, including shapes of molecules and intermolecular forces. Because these ideas are needed everywhere, Module 2 can be assessed on all three A Level papers. Examiners test definitions, multi-step mole calculations, titration practicals, oxidation number reasoning and explanations of shapes and boiling points, so accuracy with units and significant figures is important.
What you need to know
- 2.1.1 to 2.1.2 Atoms and equations Isotopes, relative isotopic mass and relative atomic mass (weighted mean relative to 1/12 of carbon-12); calculating Ar from mass spectra. Writing formulae from ions and balanced equations with state symbols.
- 2.1.3 Amount of substance n = m/M, n = cV, pV = nRT and 24.0 dm3 mol-1 at RTP; empirical and molecular formulae; water of crystallisation; percentage yield and atom economy.
- 2.1.4 Acids Acids release H+ in aqueous solution; strong acids fully dissociate, weak acids partially. Neutralisation forms salts with bases, carbonates and alkalis. Prepare standard solutions and carry out acid-base titrations.
- 2.1.5 Redox Oxidation number rules, naming with Roman numerals (for example nitrate(V)), and identifying oxidation and reduction in reactions of metals with acids.
- 2.2.1 Electron structure Shells, subshells and orbitals; filling order including 4s before 3d; configurations of atoms and ions up to krypton.
- 2.2.2 Bonding and structure Ionic, covalent and dative bonding; electron pair repulsion shapes and bond angles; electronegativity and polarity; induced dipole-dipole (London) forces, permanent dipole-dipole forces and hydrogen bonding; properties of giant and simple structures.
Common mistakes in Module 2: Foundations in Chemistry
- Leaving out water of crystallisation when calculating molar mass of hydrated salts.
- Assuming the molar gas volume of 24.0 dm3 applies at any conditions. Use pV = nRT when temperature and pressure are given, with SI units.
- Writing oxidation numbers as 2+ instead of +2, or forgetting that hydrogen is -1 in metal hydrides.
- Describing a hydrogen bond with no lone pair shown or with a bent O to H to O arrangement.
- Treating ammonium salts as forming from a reaction with water. Ammonia acts as a base by accepting H+ to form NH4+.
Try three Module 2: Foundations in Chemistry exam-style questions
1. 2.50 g of hydrated copper(II) sulfate, CuSO4.xH2O, is heated to constant mass, leaving 1.60 g of anhydrous CuSO4. Calculate x. (Mr CuSO4 = 159.6, Mr H2O = 18.0) (3 marks)
Show the mark scheme answer
Mass of water = 0.90 g, moles = 0.90 / 18.0 = 0.0500 mol; moles CuSO4 = 1.60 / 159.6 = 0.0100 mol; ratio 0.0500 / 0.0100 = 5, so x = 5.
2. Predict the shape and bond angle of the NH4+ ion and explain your answer. (3 marks)
Show the mark scheme answer
Four bonding pairs around nitrogen and no lone pairs; electron pairs repel equally to be as far apart as possible; tetrahedral, 109.5 degrees.
3. Explain, in terms of intermolecular forces, why the boiling point of H2O is higher than that of H2S. (3 marks)
Show the mark scheme answer
H2O forms hydrogen bonds between molecules because O is highly electronegative and has lone pairs; H2S has only permanent dipole-dipole and London forces, which are weaker; so more energy is needed to overcome the forces in water.
Module 2: Foundations in Chemistry FAQs
What does OCR A Level Chemistry A Module 2: Foundations in Chemistry cover?
It covers atomic structure and isotopes, formulae and equations, amount of substance, acids and titrations, redox and oxidation numbers, electron configurations, bonding, shapes of molecules and intermolecular forces.
Which papers is Module 2 examined in?
Module 2 is foundational content and can be assessed on all three OCR A Level Chemistry A papers: Periodic table, elements and physical chemistry; Synthesis and analytical techniques; and Unified chemistry.
What calculations do I need for Module 2?
You need relative atomic mass from isotope data, moles from mass, concentration and gas volumes, pV = nRT, empirical formulae, water of crystallisation, titration calculations, percentage yield and atom economy.
