Numbers
OCR A-Level Chemistry B H433
Development of Practical Skills in Chemistry
Topic overviewPlanning experimentsImplementing: apparatus, units and recording dataSignificant figures and titration calculationsGraphs, gradients and drawing a conclusionAnomalous results, precision, accuracy and types of errorCalculating uncertainties and improving a methodHazards, risk and control measuresRecording, processing and judging dataMeasuring pH, mass and volume, and choosing an indicatorReflux, distillation, purification and the standard testsPAG1 to PAG6: moles, enthalpy, qualitative analysis and organic synthesisPAG7 to PAG12: electrochemistry, rates and pH
Elements of Life
Topic overviewThe mole, relative masses and empirical formulaeConcentration, titration and writing balanced equationsOrbitals, sub-shells and electron configurationsSub-atomic particles and the evidence for the model of the atomFusion reactions and the origin of the elementsIonic, covalent, dative and metallic bonding and the four structuresMelting point, conductivity and solubility of each structureShapes of molecules and ionsThe periodic table, the blocks and trends in melting pointIon charges, the common polyatomic ions and writing formulaeGroup 2 chemistry and charge densityIonisation enthalpy and trends in reactivitySolubility rules and the tests for the common anionsHydroxide precipitates, ionic equations and identifying an unknown saltAcids, bases and preparing saltsThe electromagnetic spectrum and photon energy calculationsEmission and absorption spectra, and flame testsMass spectrometry and relative atomic mass
Developing Fuels
Topic overviewMolar gas volume and the ideal gas equationGas volume calculations and measuring a gas in the laboratoryBonding and shape in organic moleculesEnthalpy changes: definitions and standard conditionsBond enthalpiesq = mcΔT and measuring an enthalpy change in solutionBurning a fuel, correcting for heat loss, and the assumptions madeHess' law and enthalpy cyclesCatalysts, heterogeneous catalysis and catalyst poisonsCracking and how it is carried outThe pollutants from burning fuels and their effectsCatalytic converters and cutting emissionsAliphatic and aromatic compounds, functional groups and general formulaeDeducing formulae and naming a branched compoundCombustion of organic compoundsAddition of bromine and hydrogen halides, and the test for unsaturationHydrogenation and hydration of alkenesAddition polymerisationElectrophilic addition mechanismDisplayed, shortened and skeletal formulaeChain, position and functional group isomerismWhy alkenes show stereoisomerism, and the E/Z and cis/trans rulesNaming and comparing the stereoisomersSustainable fuels: benefits and risks
Elements From the Sea
Topic overviewAtom economyExtraction of the halogens from sea mineralsElectrolysis of molten salts and writing electrode half-equationsElectrolysis of aqueous solutions and the electrolysis of brineRedox as electron transferThe rules for assigning oxidation statesOxidation state calculations, and defining oxidation and reductionBalancing a redox equation with oxidation statesThe iodine-thiosulfate titration and its calculationsSystematic nomenclature of inorganic compoundsPhysical properties of the halogensHalogen reactivity and the displacement equationsObserving a displacement, and using an organic solvent or starchSilver halide precipitation and testsPreparation of the hydrogen halidesProperties of the hydrogen halidesChlorine: risks, benefits and usesDynamic equilibriumWriting a Kc expression and calculating KcWhat the magnitude of Kc tells you, and what changes itUsing the Kc expression to explain a shift in positionTemperature, pressure and catalysts on an equilibrium
The Ozone Story
Topic overviewElectronegativity and bond polarityIntermolecular bondsBoiling points and intermolecular bondsActivation enthalpy and enthalpy profilesCollision theory and the Boltzmann distributionFollowing a reaction and finding the rate from a graphCatalysts and alternative reaction routesHomogeneous catalysis and intermediatesComposition of gas mixtures by volumeRecognising and naming haloalkanesPrimary, secondary and tertiary haloalkanes, and the aminesProperties and nucleophilic substitution of haloalkanesSubstitution, nucleophiles and the SN2 mechanismRelative reactivity of the haloalkanesHomolytic and heterolytic fission, radicals and half curly arrowsInitiation, propagation and termination in a radical chain reactionOzone depletion by haloalkanesOzone in the stratosphere and troposphereRadiation of the Earth and the SunEffects of UV and visible radiation on moleculesCalculations with frequency, wavelength and energy
What's in a Medicine?
Topic overviewFormulae of oxygen-containing homologous seriesPrimary, secondary and tertiary alcoholsThe acidity of phenol compared with alcohols and carboxylic acidsThe iron(III) chloride test and esterifying a phenolEsterification and oxidising primary, secondary and tertiary alcoholsDehydration, halogenation and planning a two-step synthesisPreparing aspirin, filtering under reduced pressure and recrystallisationThin layer chromatography, Rf values and percentage yieldReflux and distillation in an organic preparationWashing, drying and redistilling a liquid productThe aims of green chemistry and atom economyCatalysts, renewable feedstocks and measuring greennessElimination reactionsThe molecular ion and fragment ionsIdentifying a compound from its fragments and the M+1 peakHow infrared absorption works and the characteristic absorptionsReading a spectrum, the fingerprint region and combining techniques
The Chemical Industry
Topic overviewRate equations, order and the rate constantDeducing the units of k and rate calculationsHalf-livesContinuous monitoring, quenching and the initial rates methodReading order from concentration-time and rate-concentration graphsThe Arrhenius equation and what each symbol meansThe ln k against 1/T plot and finding the activation enthalpyRate-determining step and mechanismEffect of conditions on the magnitude of the equilibrium constantEconomic operating conditions for an industrial processWriting a Kc expression and deducing its unitsICE-table calculations and measuring Kc experimentallyChemical reactions in industrial processesNitrogen, ammonia and the ammonium ionOxidation states of nitrogen and the tests for nitrate and ammoniumCosts, benefits and risks of industrial processes
Polymers and Life
Topic overviewAmino acids, the peptide link and hydrolysing a proteinChromatography of amino acids and Rf valuesProtein structureDNA and RNA structureBase pairing and the genetic codeMolecular recognitionEnzyme kineticsCharacteristics of enzyme catalysisAcidity of carboxylic acidsAmino acids as zwitterionsBasicity of aminesNaming acids, acyl chlorides, anhydrides, esters, aldehydes and ketonesDiols, dicarboxylic acids, amines, amides and the nylonsHydrolysis of esters and amidesReactions of acyl chloridesCondensation polymerisationOptical isomerismFurther interpretation of mass spectraChemical shift and equivalent protons in proton NMRThe n + 1 rule, integration and carbon-13 NMRCombined spectroscopic structure determination
Oceans
Topic overviewSolubility in aqueous and non-aqueous solventsLattice, hydration and solution enthalpies and how they relateMeasuring an enthalpy change of solutionCharge density and the size of enthalpy termsEntropy: qualitative treatmentTotal entropy change and the condition for feasibilityThe limiting temperature, and why a feasible reaction may not happenCalculating the entropy change of the systemThe solubility product expression, its units and calculationsPredicting precipitation and the common ion effectBronsted-Lowry theory of acids and basesStrong acids and strong basesWeak acids, Ka and pKapH of strong acids and strong basespH of weak acids, dilution and the limits of the approximationWhat a buffer is and how it resists a change in pHBuffer calculations, capacity and the natural buffersHow the greenhouse effect works and which gases cause itWhy a molecule absorbs, concentrations in ppm, and ocean chemistry
Developing Metals
Topic overviewManganate(VII) titrations and their calculationsThiosulfate titrations, recording results and good techniqueShapes of complexes and coordination numberBalancing redox equations involving acid-base reactionsSimple electrochemical cellsAction of an electrochemical cellStandard electrode potentials and calculating E°cellRusting and how it is preventedTransition metals: definition, oxidation states and coloursd-block electron configurations of the atoms and their ionsWhy transition metals show variable oxidation statesLigands and complex ionsCoordinate bonding and what makes a ligandBidentate and multidentate ligands, and finding a complex's formulaReactions of Fe2+, Fe3+ and Cu2+ with hydroxide and ammoniaCatalytic activity of transition metalsOrigin of colour in transition metal complexesColorimetry
Colour by Design
Topic overviewHow dyes attach to fibresStructure of a dye moleculeFats and oilsArenes and delocalisationRepresentations of benzene and enthalpy of hydrogenationTests for the common functional groupsIdentifying a polyfunctional molecule from a set of test resultsHalogenation and nitration of benzene and the electrophiles involvedThe nitration mechanism, sulfonation and the Friedel-Crafts reactionsDiazotisation and why it is done coldCoupling reactions, azo dyes and the route from benzeneOxidising an aldehyde and the three carbonyl testsCyanohydrin formation and its use in synthesisUsing the Data Sheet reactions to plan a routeChoosing between routes on yield and atom economyNucleophilic addition mechanismClassifying organic reactions and unfamiliar mechanismsOrigins of colour in organic moleculesHow gas-liquid chromatography separates a mixtureRetention time, peak area and the limits of the technique
Chemical Literacy
Mathematical Skills in Chemistry
Topic overviewUnits, standard form and the mole in calculationsYield, atom economy and logarithmic quantitiesSignificant figures, means and handling dataSymbols, and rearranging the standard equationsSubstituting into rearranged equationsReading spectra and kinetics graphsGradients, calibration lines and the Arrhenius plotShapes and bond angles from electron pair repulsionChiral centres, E/Z isomerism and optical activity
Development of Practical Skills in Chemistry
- 12 subtopics
- 30 things to know
- Components 01 and 03
What Development of Practical Skills in Chemistry covers
The practical strand that runs through the whole course and can be examined in writing on any of the three papers, with most weight on component 03: planning an experiment, choosing and using apparatus, handling significant figures and uncertainties, drawing conclusions from graphs, and the twelve practical activity groups.
Where it is assessed
Components 01 and 03
Practical skills, assessed in writing on both papers that carry them.
Check the OCR specification ↗The 12 subtopics
Each one has its own page.
- Planning experimentsRecall questions on independent, dependent and control variables, fair testing, and choosing conditions and apparatus before starting.Open →
- Implementing: apparatus, units and recording dataRecall questions on converting between cm³, dm³ and m³, the units of concentration and amount, and recording readings as they are taken.Open →
- Significant figures and titration calculationsRecall questions on how many figures a calculated result may carry, standard form, mean titres, and working a titration through to a concentration.Open →
- Graphs, gradients and drawing a conclusionRecall questions on lines of best fit, interpolation and extrapolation, calibration curves, gradients and tangents, and tying a conclusion to the data.Open →
- Anomalous results, precision, accuracy and types of errorRecall questions on spotting an anomalous titre, precision against accuracy, and random against systematic error.Open →
- Calculating uncertainties and improving a methodRecall questions on percentage uncertainty, combining uncertainties, weighing by difference, and reducing heat loss in a calorimetry experiment.Open →
- Hazards, risk and control measuresRecall questions on the hazards of the common reagents, corrosive against irritant, fume cupboards, and why eye protection is worn throughout.Open →
- Recording, processing and judging dataRecall questions on what a complete record contains, using a spreadsheet to process results, primary against secondary data, and judging a source.Open →
- Measuring pH, mass and volume, and choosing an indicatorRecall questions on the resolution of a burette and a balance, making up a standard solution, and matching an indicator to a titration.Open →
- Reflux, distillation, purification and the standard testsRecall questions on reflux and distillation, separating and drying an organic layer, recrystallisation, melting point, Rf values and the standard test-tube tests.Open →
- PAG1 to PAG6: moles, enthalpy, qualitative analysis and organic synthesisRecall questions on the moles determination, enthalpy measurement, Group 2 qualitative analysis, and preparing and purifying an organic product.Open →
- PAG7 to PAG12: electrochemistry, rates and pHRecall questions on the electrochemical cell experiment, continuous monitoring and initial rates, Arrhenius plots, and distinguishing acids by pH.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
A plan calls for hydrogen chloride gas to be collected over water. What is wrong with it?
Evaluation
In planning, what is the difference between a hazard and a risk?
Numbers
How do you convert between cm³ and dm³, and what are the units of concentration and of amount of substance?
Numbers
Why is a rise of 7.5 °C the same as 7.5 K, what is 2.50 g dm⁻³ sodium hydroxide (Mᵣ 40.0) in mol dm⁻³, and what is 250 cm³ in m³?
Numbers
Convert 100 kPa to pascals.
Key term
Why is a burette reading of 12.5 cm³ recorded as 12.50 cm³?
Key term
How many significant figures does 0.0250 contain?
Numbers
Why is the initial rate found from the tangent at time zero?
Key term
A mixture gives a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid, and no effervescence with the acid. What valid conclusion can be drawn?
Key term
Why must a conclusion refer directly to the recorded data?
Evaluation
What is the difference between precision and accuracy, which error does averaging reduce, and what is the uncertainty in a titre from a burette read to ±0.05 cm³?
Evaluation
How are percentage uncertainties combined when quantities are multiplied or divided?
Numbers
What effect does overshooting the end point have on the titre and on the calculated concentration?
Evaluation
What are the hazards of 2 mol dm⁻³ sodium hydroxide and of bromine water, and how do corrosive and irritant differ?
Process
Why is eye protection worn even during steps that seem safe?
Evaluation
Why is a pH meter calibrated, to what resolution is a burette read, and what uncertainty do a thermometer and a balance carry?
Numbers
What mass of sodium carbonate (Mᵣ 106.0) makes 250 cm³ of 0.100 mol dm⁻³ solution, what is the concentration when 25.0 cm³ of it is diluted to 250 cm³, and why can no indicator suit a weak acid with a weak base?
Key term
How is a separating funnel used to purify an organic liquid, and what precaution must be taken?
Numbers
Why is a gas syringe used rather than collection over water, and how is a first-order rate constant found from a half-life?
Numbers
How can pH measurement alone distinguish 0.10 mol dm⁻³ hydrochloric acid from 0.10 mol dm⁻³ ethanoic acid?
Numbers
Doubling the concentration of reactant A in an initial rates experiment makes the initial rate four times greater. State the order with respect to A.
Key term
Why is bromine water used in a fume cupboard?
Process
Why is a written method read all the way through before any apparatus is assembled?
Process
Why should a fitted line from a spreadsheet still be checked against the plotted points?
Key term
What is the difference between primary and secondary data?
Numbers
25.0 cm³ of 0.100 mol dm⁻³ solution is diluted to 250 cm³. What is the new concentration?
Process
Why is an enthalpy change measured in a polystyrene cup usually less exothermic than the accepted value?
Process
In what order are the three main operations carried out when a haloalkane is prepared and purified from an alcohol?
Process
In qualitative analysis of organic functional groups, which reagent detects a carbonyl group, and how is an aldehyde then distinguished from a ketone?
Take Development of Practical Skills in Chemistry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Accuracy vs Precision
Accuracy: how close a measurement is to the true value. Precision: how closely repeated measurements agree with one another.
Random error vs Systematic error
Random error: error that varies unpredictably and is reduced by repeating and averaging. Systematic error: error that shifts every reading the same way and is not reduced by repeating.
Interpolation vs Extrapolation
Interpolation: reading a value from within the range of the measured points. Extrapolation: extending a line beyond the measured points to read a value.
Questions from this topic
Each one with the model answer underneath.
- 1
In a chemistry investigation, what is meant by the independent variable?
Model answer
It is the quantity the experimenter deliberately changes, such as the temperature or the initial concentration of a reactant.
- 2
What is the dependent variable?
Model answer
It is the quantity that is measured to see how it responds to the change made, such as the volume of gas collected or the time taken for a colour to appear.
- 3
What is a control variable, and why do control variables matter?
Model answer
A control variable is a quantity kept the same throughout so that it cannot affect the result; without them any change in the dependent variable cannot be attributed to the independent variable.
- 4
You are investigating how temperature affects the rate at which magnesium reacts with hydrochloric acid. Name the independent and dependent variables and two variables you must control.
Model answer
The independent variable is the temperature of the acid and the dependent variable is the volume of hydrogen collected in a fixed time; the concentration and volume of acid, and the mass, surface area and form of the magnesium, must be kept constant.
- 5
When the concentration of one reactant is varied in a rates experiment, why is the total volume of the mixture kept the same in every run?
Model answer
Diluting to a fixed total volume means only the one concentration being investigated changes, so the concentrations of all other species stay constant.
- 6
Why is a water bath rather than a Bunsen flame chosen when a flammable organic liquid must be warmed?
Model answer
The vapour of a flammable liquid can be ignited by a naked flame, so heat is supplied indirectly through hot water instead.
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Six ways to work the same material.
Development of Practical Skills in Chemistry revision questions
- What does Development of Practical Skills in Chemistry cover in OCR A-Level Chemistry B?
- 12 subtopics: planning experiments, implementing: apparatus, units and recording data, significant figures and titration calculations, graphs, gradients and drawing a conclusion, anomalous results, precision, accuracy and types of error, calculating uncertainties and improving a method, hazards, risk and control measures, recording, processing and judging data, measuring ph, mass and volume, and choosing an indicator, reflux, distillation, purification and the standard tests, pag1 to pag6: moles, enthalpy, qualitative analysis and organic synthesis and pag7 to pag12: electrochemistry, rates and ph. Each one has its own page with questions and model answers.
- How is Development of Practical Skills in Chemistry organised?
- By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Development of Practical Skills in Chemistry, on a schedule.
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