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GCSEEdexcel
Chemistry
Exam Questions
Scientific models: what they are and why we use themNewDeveloping hypotheses from scientific ideasNewVariables: independent, dependent and controlNewWriting a clear, testable predictionNewPlanning a method: accuracy, precision and rangeNewRisk assessments: hazards, risks and control measuresNewChoosing apparatus for accuracy (pipettes, burettes, balances)NewRecording results in tables with headings and unitsNewDrawing graphs: choosing scales and plotting pointsNewUsing lines of best fit and interpreting trendsNewReliability: repeats, means and anomaliesNewUncertainty: resolution, range and systematic vs random errorNewEvaluating a method and suggesting improvementsNewUsing SI units, prefixes and standard formNewSignificant figures in practical calculationsNewRequired practical sign-off: what must be recorded and why (Pearson Qualifications)New
Memorising common element symbols and simple formulaeNewWriting formulae for common ionsNewTurning word equations into symbol equationsNewBalancing symbol equations step-by-stepNewState symbols: solid, liquid, gas and aqueousNewWriting ionic equations from full equationsNewIdentifying common hazard symbolsNewMatching hazard symbols to lab precautionsNewEvaluating risk in a practical method and improving safety (Pearson Qualifications)New
How the Dalton model changed with new discoveriesNewInside the atom: protons, neutrons and electronsNewRelative charge and relative mass of subatomic particlesNewWhy atoms have equal numbers of protons and electronsNewAtomic number and mass numberNewIsotopes and why they existNewCalculating protons, neutrons and electrons in atoms and ionsNewRelative atomic mass from isotope abundance dataNewMendeleev’s periodic table: evidence and predictionsNewPeriods and groups: what the table showsNewMetals vs non-metals from position and structureNewElectronic configuration for the first 20 elements (shell model)NewLinking electron configuration to group and periodNewForming ions by electron transfer (dot-and-cross)NewNaming ionic compounds: -ide vs -ateNewWriting ionic formulae from ion chargesNewIonic lattices and why ionic compounds have high melting pointsNewWhen ionic substances conduct electricity (solid vs molten vs aqueous)NewCovalent bonds as shared pairs of electronsNewDot-and-cross for key molecules (H2, HCl, H2O, CH4, O2, CO2)NewIntermolecular forces and why simple molecules have low boiling pointsNewDiamond vs graphite: structure and propertiesNewGraphene and fullerenes: structure and key propertiesNewMetals: delocalised electrons and metallic bondingNewPolymers as long carbon-chain molecules (intro)NewLimits of models (dot-and-cross, ball-and-stick, 2D/3D)NewRelative formula mass (Mr) calculationsNewPercentage by mass calculationsNewEmpirical formula from reacting massesNewEmpirical formula from percentage compositionNewConservation of mass in reactionsNewReacting masses from balanced equationsNewConcentration calculations (g/dm³ and mol/dm³)NewThe mole as “amount of substance”NewLimiting reactants and “excess” in calculations (Pearson Qualifications)New
Particle model: solids, liquids and gasesNewNaming changes of state (melting, boiling, condensing, freezing, sublimation)NewExplaining changes of state using energy and particle movementNewUsing data to predict state at given conditionsNew“Pure” in chemistry vs everyday “pure”NewPure substances vs mixtures: key differencesNewMelting point range vs sharp melting point (purity)NewSimple distillation: when and why it worksNewFractional distillation: separating liquids with different boiling pointsNewFiltration: separating insoluble solids from liquidsNewCrystallisation: making a soluble salt from solutionNewPaper chromatography: stationary and mobile phaseNewInterpreting chromatograms for purity and identityNewCalculating and using Rf valuesNewCore practical: inks by chromatography and simple distillation (Pearson Qualifications)NewChoosing the best separation method from substance propertiesNewMaking water potable: sedimentation, filtration and chlorinationNewDistillation to make seawater potableNewWhy water used in analysis must be salt-free (Pearson Qualifications)New
Acids and alkalis as H+ and OH– sourcesNewThe pH scale and what pH 7 meansNewIndicators: litmus, methyl orange, phenolphthaleinNewpH and ion concentration (10× rule)NewCore practical: tracking pH during neutralisation (Ca(OH)2/CaO) (Pearson Qualifications)NewConcentrated vs dilute (amount of solute)NewStrong vs weak acids (degree of dissociation)NewBases vs alkalis (soluble base)NewAcids reacting with metals: products and observationsNewAcids reacting with metal oxides/hydroxides: neutralisation to saltsNewAcids reacting with carbonates: CO2 productionNewGas tests: hydrogen (pop) and carbon dioxide (limewater)NewNeutralisation as acid + baseNewNeutralisation at particle level: H+ + OH– → H2ONewMaking soluble salts using an insoluble reactant (excess, filter, crystallise)NewMaking soluble salts using a soluble reactant (titration needed)NewCore practical: preparing hydrated copper sulfate crystals (water bath) (Pearson Qualifications)NewTitration method to make a pure dry salt (overview)NewSolubility rules for common saltsNewPredicting precipitates from solubility rulesNewMaking an insoluble salt by precipitation (filter, wash, dry)NewElectrolytes: ionic compounds molten or in solutionNewElectrolysis as decomposition using direct currentNewIon movement to electrodes (anions → anode, cations → cathode)NewPredicting products: aqueous electrolysis (competition rules)NewPredicting products: molten ionic compoundsNewHalf-equations at anode and cathodeNewOxidation and reduction as electron loss/gainNewElectrolysis: oxidation at anode, reduction at cathodeNewCopper purification using electrolysis (copper electrodes)NewCore practical: electrolysis of CuSO4 with inert vs copper electrodes (Pearson Qualifications)New
Reactivity of metals from reactions with water, acids and salt solutionsNewDisplacement reactions as redox (electron transfer)NewThe reactivity series (including carbon and hydrogen reference points)NewMetals in ores vs native metals (uncombined elements)NewOxidation and reduction in terms of oxygen gain/lossNewExtraction as reduction of oresNewCarbon reduction vs electrolysis: choosing a method (cost + reactivity)NewIron extraction idea (meaning of “reduction by carbon”)NewAluminium extraction by electrolysis (why it’s expensive)NewBioleaching and phytoextraction (why they’re alternatives)NewCorrosion resistance and reactivity series linksNewRecycling metals: environmental and economic benefitsNewLife cycle assessment: raw materials → manufacture → use → disposalNewInterpreting LCA data to make a judgementNewReversible reactions and the ⇌ symbolNewDynamic equilibrium: forward rate = reverse rateNewAmmonia formation as a reversible reaction (Haber overview)NewHaber process conditions: temperature, pressure, catalyst (Pearson Qualifications)NewPredicting equilibrium shifts (temperature, pressure, concentration) (Pearson Qualifications)New
Transition metals: typical properties (density, mp, coloured compounds, catalysis)NewCorrosion as oxidation of metalsNewPreventing rust: exclude oxygen, exclude water, sacrificial protectionNewElectroplating: why and how it improves appearance/corrosion resistanceNewAlloys: why mixing metals changes propertiesNewWhy steel is an alloy (and why pure iron is limited)NewLinking metal uses to properties (Al, Cu, Au; magnalium, brass)NewConcentration in mol/dm³: calculating from moles and volumeNewConverting between g/dm³ and mol/dm³NewCore practical: acid–alkali titration (apparatus, method, endpoint) (Pearson Qualifications)NewTitration calculations: finding unknown concentration or volumeNewPercentage yield: actual vs theoreticalNewWhy yield is usually <100% (incomplete, losses, side reactions)NewAtom economy: what it means for sustainabilityNewCalculating atom economy from equationsNewChoosing pathways using yield, atom economy, rate, equilibrium, by-productsNewMolar volume at r.t.p. (24 dm³ per mole) and what it meansNewUsing molar volume in reacting-mass calculationsNewAvogadro’s law: using mole ratios to compare gas volumesNewHaber process revisited: equilibrium as a dynamic processNewConditions affecting rate of reaching equilibrium (T, P, concentration, catalyst)NewIndustry trade-offs: acceptable yield in acceptable timeNewNPK fertilisers: what the letters mean and why plants need themNewAmmonia + nitric acid → fertiliser salt (ammonium nitrate concept)NewMaking ammonium sulfate in the lab (small-scale method)NewComparing lab vs industrial-scale fertiliser manufactureNewChemical cells: voltage until a reactant is used upNewHydrogen–oxygen fuel cells: reactants and productsNewEvaluating fuel cells for specific uses (pros/cons) (Pearson Qualifications)New
Locating group 1, group 7 and group 0 from periodic table positionNewGroup 1 properties: soft and low melting pointsNewGroup 1 reactions with water (Li, Na, K): observations and productsNewGroup 1 reactivity trend down the groupNewExplaining group 1 trend using electron configurationNewGroup 7 colours and states (Cl2, Br2, I2)NewGroup 7 physical trends down the groupNewTest for chlorine gasNewHalogens reacting with metals to form metal halidesNewHydrogen halides and acidic solutions (pattern down the group)NewHalogen displacement reactions with halide ionsNewUsing displacement to order halogen reactivity (including astatine)NewDisplacement as redox: identifying what’s oxidised and reducedNewExplaining group 7 reactivity trend using electron configurationNewWhy noble gases are inert (full outer shell)NewUses of noble gases from inertness, low density and non-flammabilityNewTrends in noble gas physical properties down the group (Pearson Qualifications)New
What “rate of reaction” means in real experimentsNewCore practical: rate using gas volume (marble chips + acid) (Pearson Qualifications)NewCore practical: rate using disappearing cross (thiosulfate + acid) (Pearson Qualifications)NewDrawing and interpreting rate graphs (steeper = faster)NewCalculating rate from gradients and time dataNewCollision theory: why reactions happenNewEffect of concentration on rate (collision frequency)NewEffect of temperature on rate (collision energy and activation energy)NewEffect of surface area on rate (exposed particles)NewCatalysts: lowering activation energyNewEnzymes as biological catalysts (basic idea)NewExothermic vs endothermic reactions (energy out vs in)NewReaction profiles: reading energy diagramsNewActivation energy on reaction profilesNewBond breaking vs bond making and energy changesNewCalculating overall energy change using bond energiesNewUsing profiles to compare catalysed vs uncatalysed reactions (Pearson Qualifications)New
Hydrocarbons as compounds of only hydrogen and carbonNewCrude oil as a complex mixture of hydrocarbonsNewCrude oil as a finite resource and why that mattersNewFractional distillation of crude oil: how separation worksNewFractions and their uses (gases, petrol, kerosene, diesel, fuel oil, bitumen)NewWhy fraction properties change with chain length (bp, viscosity, ignition)NewHomologous series: definition and CH2 patternNewComplete combustion of hydrocarbons (products + energy)NewIncomplete combustion: carbon monoxide and sootNewWhy carbon monoxide is toxicNewProblems from incomplete combustion in appliancesNewSulfur impurities and sulfur dioxide formationNewAcid rain from sulfur dioxide: impactsNewNitrogen oxides from high-temperature enginesNewHydrogen vs petrol as a car fuel (advantages and disadvantages)NewFossil fuels: petrol/kerosene/diesel from crude oil; methane from natural gasNewCracking: turning long alkanes into shorter alkanes and alkenesNewWhy cracking is needed (demand for fuels and feedstock)NewEarth’s early atmosphere from volcanic gasesNewEarly atmosphere evidence (little O2, lots CO2, water vapour)NewOcean formation by condensation of water vapourNewCO2 decrease by dissolving in oceansNewOxygen increase from photosynthesis (primitive plants)NewTest for oxygen (relights glowing splint)NewGreenhouse effect: how gases absorb and re-radiate heatNewEvaluating evidence for human-caused climate change (correlation + uncertainty)NewToday’s atmosphere compositionNewImpacts of increased CO2 and methane and possible mitigation (Pearson Qualifications)New
Why each ion test must be uniqueNewFlame tests: identifying Li+, Na+, K+, Ca2+, Cu2+NewCation tests with sodium hydroxide: Al3+, Ca2+, Cu2+, Fe2+, Fe3+, NH4+NewTest for ammonia gasNewCarbonate test: acid then CO2 confirmationNewSulfate test: acid then barium chlorideNewHalide tests: nitric acid then silver nitrate (Cl–, Br–, I–)NewCore practical: identifying ions in unknown salts (Pearson Qualifications)NewUsing test results to deduce the ions presentNewInstrumental methods: why they can be faster/more accurateNewFlame photometry: calibration curve to find concentrationNewFlame photometry: identifying ions from reference resultsNewDrawing and naming alkanes (methane, ethane, propane, butane)NewWhy alkanes are saturatedNewDrawing and naming alkenes (ethene, propene, butenes)NewWhy alkenes are unsaturated and the C=C functional groupNewAddition reaction: alkene + bromine (structures of reactants/products)NewBromine water test for unsaturation (alkenes vs alkanes)NewCombustion of alkanes and alkenes as oxidationNewWhat polymers are (repeating units, high Mr)NewMaking poly(ethene) from ethene (addition polymerisation)NewOther addition polymers: poly(propene), PVC, PTFENewLinking monomers and polymers (deducing one from the other)NewPolymer uses linked to properties (PE, PP, PVC, PTFE)NewPolyesters as condensation polymers (water formed each link)NewProblems with polymers (landfill persistence, combustion gases, sorting)NewEvaluating polymer recycling (economic and environmental trade-offs)NewNatural polymers: DNA, starch and proteins (what they’re made from)NewDrawing alcohols (methanol, ethanol, propan-1-ol, butan-1-ol)NewAlcohol functional group and dehydration to alkenesNewCore practical: comparing heats of combustion of alcohols (Pearson Qualifications)NewDrawing carboxylic acids (methanoic to butanoic)NewCarboxylic acid functional group and acidic propertiesNewOxidising ethanol to ethanoic acid (and extension idea)NewUsing functional groups to predict reactions in a homologous seriesNewEthanol by fermentation (yeast enzymes)NewConcentrating ethanol by fractional distillation after fermentationNewNanoparticles: size compared to atoms and moleculesNewNanoparticles: surface area to volume ratio and uses (e.g. sunscreens)NewNanoparticles: possible risksNewComparing materials using data (glass/clay ceramics, polymers, composites, metals)NewSelecting materials for uses based on properties and data (Pearson Qualifications)New
