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
Nitrogen, phosphorus and potassium in agriculture
- 3 things to know
- Paper 2
Overview
The three elements in an NPK fertiliser and what nitrogen, phosphorus and potassium each do for a plant, why fertiliser compounds must be soluble, choosing a fertiliser for a leaf crop, making ammonium nitrate and ammonium sulfate by neutralisation, fertiliser manufacture as a set of integrated processes with its nitric acid, Contact process and raw materials, and crystallising the solid salt.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is phosphorus needed for in a plant?
Key term
Why must the compounds in a fertiliser be soluble in water?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the three elements supplied by an NPK fertiliser.
Model answer
Nitrogen, phosphorus and potassium.
- 2
What does nitrogen do for a growing plant?
Model answer
It is needed to make proteins, giving strong growth of leaves and stems.
- 3
What is phosphorus needed for in a plant?
Model answer
Healthy root growth and the development of flowers, seeds and fruit.
- 4
What does potassium do for a plant?
Model answer
It helps the plant make and move food and use water, improving fruit quality and resistance to disease.
- 5
Why must the compounds in a fertiliser be soluble in water?
Model answer
Roots can only take up ions that are dissolved in the soil water.
- 6
What is meant by an NPK fertiliser?
Model answer
A fertiliser containing compounds that supply all three of nitrogen, phosphorus and potassium.
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