GCSE Chemistry
Chemical changes
revision.
Acids and alkalis, electrolysis, rates, catalysts and energy changes.
Chemical changes guides
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Students type: temperature change required practical GCSE Chemistry
Open guide Revision guideEquilibria and Le Chatelier’s principleStudents type: Le Chatelier’s principle GCSE Chemistry
Open guide Revision guideThe Haber processStudents type: Haber process conditions 450°C 200 atm
Open guide Revision guideBond energiesStudents type: bond energy calculations ΔH GCSE Chemistry
Open guide Revision guideReaction profilesStudents type: reaction profile activation energy GCSE Chemistry
Open guide Revision guideExothermic and endothermic reactionsStudents type: exothermic vs endothermic GCSE Chemistry
Open guide Revision guideRates required practicalStudents type: rates of reaction required practical GCSE Chemistry
Open guide Revision guideCatalystsStudents type: how catalysts lower activation energy GCSE
Open guide Revision guideCollision theoryStudents type: collision theory GCSE Chemistry rates
Open guide Revision guideExtracting aluminiumStudents type: aluminium extraction cryolite GCSE Chemistry
Open guide Revision guideElectrolysis of solutionsStudents type: electrolysis of aqueous solutions GCSE Chemistry
Open guide Revision guideElectrolysis of molten saltsStudents type: electrolysis molten lead bromide GCSE Chemistry
Open guideAcids and alkalis
pH, strong and weak acids, neutralisation equations, salt names, carbonates, metals and the titration practical.
Electrolysis
Molten and aqueous electrolysis, cathode and anode, half equations, aluminium extraction and the brine cell.
Rates of reaction
Collision theory, concentration, pressure, surface area, temperature, catalysts, rate graphs and reversible reactions.
Energy changes
Exothermic and endothermic reactions, reaction profiles, activation energy, bond energies and simple cells.
The pH scale and indicators
GCSE Chemistry revision on the pH scale and indicators: H⁺(aq) and OH⁻(aq), universal indicator colours, and the ten-fold change in hydrogen ion concentration.
Neutralisation and salts
GCSE Chemistry revision on neutralisation and salts: acid plus metal, base or carbonate, naming chlorides, sulfates and nitrates, and writing equations with state symbols.
Strong and weak acids
GCSE Chemistry revision on strong and weak acids (Higher): complete versus partial ionisation, pH at the same concentration, and why strength is not the same as concentration.
Titration
GCSE Chemistry revision on titration: burette, pipette, indicator, concordant titres within 0.10 cm³, the mean, and calculating concentration from a worked titre.
The reactivity series
GCSE Chemistry revision on the reactivity series: potassium to gold, displacement, metal plus acid or water, and linking reactivity to how easily atoms form positive ions.
Metal extraction
GCSE Chemistry revision on metal extraction: native metals, reduction of oxides with carbon, electrolysis for metals above carbon, and phytomining or bioleaching for copper.
Electrolysis of molten salts
GCSE Chemistry revision on electrolysis of molten salts: mobile ions, cathode reduction, anode oxidation, and half equations such as Pb²⁺ + 2e⁻ → Pb.
Electrolysis of solutions
GCSE Chemistry revision on electrolysis of aqueous solutions: hydrogen versus metal at the cathode, halogen versus oxygen at the anode, and the brine cell.
Extracting aluminium
GCSE Chemistry revision on extracting aluminium: bauxite, cryolite to lower the melting point, carbon anodes, and half equations for Al³⁺ and O²⁻.
Collision theory
GCSE Chemistry revision on collision theory: successful collisions, activation energy, and how concentration, pressure, surface area and temperature change rate.
Catalysts
GCSE Chemistry revision on catalysts: alternative pathway, lower activation energy, reaction profiles, and named examples including enzymes and iron in the Haber process.
Rates required practical
GCSE Chemistry revision on the rates required practical: marble chips and acid, sodium thiosulfate and HCl, measuring mass, gas volume or a disappearing cross, and fair tests.
Exothermic and endothermic reactions
GCSE Chemistry revision on exothermic and endothermic reactions: energy transfer to or from the surroundings, temperature change, and everyday examples including combustion and sports packs.
Reaction profiles
GCSE Chemistry revision on reaction profiles: activation energy, ΔH, exothermic and endothermic sketches, and how a catalyst lowers the hump but not the enthalpy change.
Bond energies
GCSE Chemistry revision on bond energies: bond breaking is endothermic, bond making is exothermic, and ΔH = energy in to break bonds minus energy out when bonds form.
The Haber process
GCSE Chemistry revision on the Haber process: N₂ + 3H₂ ⇌ 2NH₃, iron catalyst, 450 °C and 200 atmospheres as compromise conditions, recycling, and ammonia for fertilisers.
Equilibria and Le Chatelier’s principle
GCSE Chemistry revision on reversible reactions, dynamic equilibrium in a closed system, and Le Chatelier’s principle for concentration, pressure and temperature, including why catalysts do not change yield.
Temperature change required practical
Plan the GCSE Chemistry temperature-change investigation: exothermic or endothermic dissolving or neutralisation, thermometer readings, insulation, fair test, mean temperature change and graph.
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