Key term
OCR GCSE Chemistry A J248
Chemical Reactions
Topic overviewWriting formulae of elements and compoundsBalanced equations, and deducing formulae from ionsState symbols in equationsConservation of mass, and changes of mass in open systemsExothermic and endothermic reactions, and reaction profilesActivation energy and why reactions need itOxidation and reduction in terms of oxygenAcids, alkalis and neutralisationThe ionic equation for neutralisation, and reactions of acidsThe pH scale, acidity and alkalinityMeasuring pH with indicators and pH metersProducts at the electrodes, and molten ionic compoundsElectrolysis of aqueous solutionsInert and non-inert electrodes
Elements, Compounds and Mixtures
Topic overviewPurity, and melting point dataRelative formula mass and empirical formulaeFormulations, and separating mixturesPaper and thin layer chromatographyInterpreting chromatograms and Rf valuesChoosing a purification methodMetals and non-metals in the Periodic TableElectron arrangement and position in the Periodic TableIonic, covalent and metallic bonding comparedDot and cross diagrams, and the limits of modelsReactions, electron arrangement and Mendeleev's tableCarbon's four bonds, and the variety of organic compoundsDiamond, graphite, fullerenes and grapheneBond strength, intermolecular forces and predicting stateBulk properties of ionic, molecular and giant structuresNanoparticles: size and surface area to volumeUses and risks of nanoparticulate materials
Global Challenges
Topic overviewExtracting metals by reduction and by electrolysisThe Haber process and fertiliser productionNitrogen, phosphorus and potassium in agricultureLife cycle assessmentRecycling, and the decisions behind itAlloys, and the corrosion of metalsComparing glass, ceramics, polymers, composites and metalsFunctional groups and homologous seriesPredicting the products of organic reactionsAddition polymerisationDNA and other natural polymersFractional distillation of crude oilThe fractions, and crude oil as a feedstockDependence on hydrocarbons, and crackingChemical cells and fuel cellsThe Earth's early atmosphere, and how oxygen developedThe greenhouse effect, and evidence for climate changeEffects of carbon dioxide and methane, and air pollutantsProducing potable water
Monitoring and Controlling Chemical Reactions
Topic overviewCarrying out an acid–alkali titrationTheoretical mass and percentage yieldAtom economy and its calculationMeasuring the rate of a reaction, and rate graphsFactors affecting rate, and collision theorySurface area and rateCatalysts and how they workReversible reactions and dynamic equilibriumActivation energy, and enzymes as catalysts
Particles
Predicting and Identifying Reactions
Topic overviewGroups 1, 7 and 0, and why they behave as they doTransition metalsPredicting reactivity from the Periodic TableReactivity of metals with water and acidsTests for oxygen, hydrogen, carbon dioxide and chlorineTests for aqueous cations and anionsFlame tests, and identifying metal ionsIdentifying a species from test resultsInstrumental methods of analysis
Global Challenges
Predicting the products of organic reactions
- 2 things to know
- Paper 2
Overview
The products and equations for the complete combustion of propane and ethanol, adding bromine or hydrogen across the double bond of an alkene and the bromine water test, oxidising alcohols such as ethanol to carboxylic acids, why the functional group decides the reactions of a whole homologous series, and using it to predict the products of unfamiliar compounds.
What you need to know
Answer each one before you reveal it.
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Key term
Give the balanced equation for the complete combustion of propane.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What are the products when a hydrocarbon burns completely in plenty of oxygen?
Model answer
Carbon dioxide and water.
- 2
Give the balanced equation for the complete combustion of propane.
Model answer
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.
- 3
Give the balanced equation for the complete combustion of ethanol.
Model answer
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O.
- 4
What is formed when bromine adds across the double bond of ethene, and what is its formula?
Model answer
Dibromoethane is formed, with the formula C₂H₄Br₂.
- 5
What happens to orange bromine water when it is shaken with an alkene, and why?
Model answer
It is decolourised, because the bromine adds across the carbon–carbon double bond to form a colourless product.
- 6
Which product is formed when hydrogen adds across the double bond of propene?
Model answer
Propane, C₃H₈.
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