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
Developing Fuels
- 24 subtopics
- 56 things to know
- Components 01, 02 and 03
What Developing Fuels covers
The storyline that carries thermochemistry and the first organic chemistry: gas volumes and the ideal gas equation, enthalpy changes and how they are measured, bond enthalpies and Hess' law, catalysis and cracking, the pollutants from burning fuels, and the alkanes, alkenes and polymers.
Where it is assessed
Components 01, 02 and 03
Storyline content, drawn on by all three written papers.
Check the OCR specification ↗The 24 subtopics
Each one has its own page.
- Molar gas volume and the ideal gas equationRecall questions on molar gas volume at RTP, the ideal gas equation and the gas constant, and the units each quantity must be in.Open →
- Gas volume calculations and measuring a gas in the laboratoryRecall questions on finding a volume or an amount from pV = nRT, reading volume ratios off an equation, and why a measured volume comes out low.Open →
- Bonding and shape in organic moleculesRecall questions on sigma and pi bonding, why rotation is free about C-C but not C=C, and the bond angles around a saturated and an unsaturated carbon.Open →
- Enthalpy changes: definitions and standard conditionsRecall questions on exothermic and endothermic changes, standard conditions and standard states, and the definitions of the standard enthalpy changes.Open →
- Bond enthalpiesRecall questions on why bond enthalpies are averages, whether breaking and making release or absorb energy, and calculating ΔH from them.Open →
- q = mcΔT and measuring an enthalpy change in solutionRecall questions on q = mcΔT and what each symbol means, and on measuring an enthalpy change in a polystyrene cup.Open →
- Burning a fuel, correcting for heat loss, and the assumptions madeRecall questions on the burning-fuel calorimeter, why the result is less exothermic than the data book value, and correcting by extrapolation.Open →
- Hess' law and enthalpy cyclesRecall questions on why an indirect route gives the same answer, building a cycle from combustion or formation data, and checking it has been used correctly.Open →
- Catalysts, heterogeneous catalysis and catalyst poisonsRecall questions on how a catalyst works, adsorption, reaction and desorption on a surface, and why a poisoned catalyst is an economic problem.Open →
- Cracking and how it is carried outRecall questions on why cracking matters to the oil industry, why a product must be unsaturated, and how a hydrocarbon is cracked in the laboratory.Open →
- The pollutants from burning fuels and their effectsRecall questions on particulates, unburnt hydrocarbons, carbon monoxide and the oxides of nitrogen and sulfur, and the effects of each.Open →
- Catalytic converters and cutting emissionsRecall questions on what a catalytic converter removes and how, why it works poorly when cold, and how sulfur dioxide is removed from flue gas.Open →
- Aliphatic and aromatic compounds, functional groups and general formulaeRecall questions on aliphatic, aromatic and arene, saturation, functional groups and homologous series, and the general formulae.Open →
- Deducing formulae and naming a branched compoundRecall questions on deducing a molecular formula from a general one, the stems for one to ten carbons, and choosing and numbering the main chain.Open →
- Combustion of organic compoundsRecall questions on the conditions for complete combustion, the extra products when it is incomplete, and writing balanced combustion equations.Open →
- Addition of bromine and hydrogen halides, and the test for unsaturationRecall questions on why a C=C bond is reactive, the bromine water test and what it shows, and the products with a hydrogen halide.Open →
- Hydrogenation and hydration of alkenesRecall questions on the conditions for hydrogenation and why nickel is used industrially, and on the two routes from ethene to ethanol.Open →
- Addition polymerisationRecall questions on monomers and repeat units, deducing one from the other, and naming the common addition polymers.Open →
- Electrophilic addition mechanismRecall questions on what an electrophile is, the steps by which hydrogen bromide adds to ethene, and the intermediate formed.Open →
- Displayed, shortened and skeletal formulaeRecall questions on what each kind of formula shows, reading a skeletal formula, and choosing which to use.Open →
- Chain, position and functional group isomerismRecall questions on the three kinds of structural isomerism and on listing the isomers of a given molecular formula.Open →
- Why alkenes show stereoisomerism, and the E/Z and cis/trans rulesRecall questions on why there is no rotation about C=C, the condition for stereoisomerism, and the E/Z priority rules.Open →
- Naming and comparing the stereoisomersRecall questions on naming the stereoisomers of but-2-ene and 1,2-dichloroethene, and why their melting and boiling points differ.Open →
- Sustainable fuels: benefits and risksRecall questions on biofuels and alternative fuels, carbon neutrality, and weighing the benefits of a fuel against its risks.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
How is the ideal gas equation rearranged for temperature, what volume of oxygen burns 100 cm³ of methane completely, and why is collecting carbon dioxide over water a poor method?
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Why might a measured gas volume come out low, to how many significant figures should an amount from a 48 cm³ syringe reading be quoted, and what happens to a gas volume if its kelvin temperature doubles?
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What amount of gas, in moles, is present in 720 cm³ of oxygen at RTP?
Numbers
Why is a π bond weaker than a σ bond, why can groups rotate about C–C but not about C=C, and what is the bond angle around a saturated carbon?
Numbers
What is the shape and bond angle around each carbon of a C=C double bond?
Key term
How many σ bonds and how many π bonds are there in a molecule of ethene?
Key term
What is an endothermic reaction, what does the sign of ΔH tell you, and what is a standard state?
Numbers
Can an enthalpy change of formation be positive, why is neutralisation defined per mole of water, and what are the units?
Numbers
How does ΔH for 2H₂ + O₂ → 2H₂O compare with ΔH for H₂ + ½O₂ → H₂O, what equation defines the enthalpy change of formation of ethanol, and which formation enthalpy is also a combustion enthalpy?
Key term
Why is a temperature always specified alongside a standard enthalpy change?
Key term
Why does the definition of bond enthalpy use the word average, and is bond breaking or bond making exothermic?
Numbers
In terms of bonds, what makes a reaction exothermic, and how does bond enthalpy relate to bond length and bond order?
Numbers
Which is shorter, a C–C or a C=C bond, what do bond enthalpies of 347 and 612 kJ mol⁻¹ show about the π bond, and why do bond enthalpy calculations strictly apply only to gases?
Key term
Why does almost every reaction need some energy supplied before it will start?
Key term
Why does it not matter whether ΔT is in °C or K, and why are a polystyrene cup and a copper calorimeter each chosen?
Key term
Give two reasons why an experimental enthalpy change of combustion comes out less exothermic than the data book value.
Evaluation
Why is it assumed that a dilute solution has the same density and specific heat capacity as water?
Key term
Why is the energy absorbed by the polystyrene cup itself usually ignored?
Process
Why can an enthalpy change be found by an indirect route, why are elements left out, and how do you check a cycle?
Process
Why is finding an enthalpy change from a Hess cycle described as an indirect determination?
Key term
On an enthalpy level diagram for an exothermic reaction, where do the products lie?
Key term
What is a catalyst, what makes one heterogeneous, and what is an example from the chemistry of fuels?
Key term
Why must the adsorption not be too strong?
Key term
Why does a cracking catalyst gradually lose its activity in use?
Numbers
How are particulates formed, under what conditions does carbon monoxide form, and what is the equation for incomplete combustion of octane?
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What are the equations for nitrogen monoxide forming in an engine, and where do the oxides of sulfur come from?
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What are the equations for a catalytic converter removing carbon monoxide, and for removing sulfur dioxide with calcium oxide?
Key term
What do aliphatic and aromatic mean, and what is an arene?
Numbers
What is the molecular formula of benzene, and what do saturated and unsaturated mean?
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What are the general formulae of the alkanes, the alkenes and the cycloalkanes?
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An alkane molecule contains 20 hydrogen atoms. Deduce its molecular formula and name.
Numbers
Deduce the molecular formula of the straight-chain alcohol with four carbon atoms.
Key term
What condition is needed for complete combustion, what extra products appear when it is incomplete, and why does incomplete combustion happen?
Numbers
What are the equations for the complete combustion of propane, octane and ethene?
Numbers
What are the equations for burning ethanol and methanol, and why does an alcohol need less oxygen per carbon than an alkane?
Key term
Why is combustion classified as an oxidation reaction?
Numbers
Why is a C=C bond more reactive than a C–C bond, what do bond enthalpies of 347 and 612 kJ mol⁻¹ show about the double bond, and what is the equation for ethene with bromine?
Numbers
What is seen when bromine water is shaken with an alkane, why does the test still work on a molecule with several functional groups, and what is the equation for ethene with hydrogen bromide?
Numbers
What is the equation for hydrogenating ethene, why is nickel preferred to platinum, and what forms when water adds to a C=C?
Process
What is a monomer, what happens to the double bond in addition polymerisation, and what is the repeat unit of poly(ethene)?
Numbers
What are the repeat units of poly(propene) and poly(chloroethene), and how is a polymer formula written?
Numbers
Why does a repeat unit share the monomer's molecular formula, and how many repeat units are in a poly(ethene) chain of Mᵣ 42 000 and a poly(chloroethene) chain of Mᵣ 75 000 (monomer Mᵣ 62.5)?
Numbers
Why does poly(ethene) fail to decolourise bromine water even though ethene does?
Key term
What is an addition reaction and an electrophile, and what is the first step when hydrogen bromide adds to ethene?
Process
Describe the second step of the electrophilic addition of hydrogen bromide to ethene.
Key term
Why is the H–Br bond polar to begin with?
Key term
What is produced if ethene reacts with bromine in the presence of sodium chloride solution?
Numbers
In a skeletal formula, what does the end of a line stand for?
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Define structural isomers.
Key term
Give a cycloalkane isomer of but-1-ene and say what type of isomerism this is.
Numbers
How does stereoisomerism about a C=C bond arise, and when are the E/Z and cis/trans names used?
Numbers
Where are the methyl groups in cis-but-2-ene?
Process
Explain the difference between structural isomers and stereoisomers.
Key term
What is the only product formed when hydrogen burns?
Numbers
Write the equation for the combustion of hydrogen.
Take Developing Fuels further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Enthalpy change of formation vs Enthalpy change of combustion
Enthalpy change of formation: the enthalpy change when one mole of a compound forms from its elements in their standard states. Enthalpy change of combustion: the enthalpy change when one mole of a substance burns completely in oxygen.
Exothermic reaction vs Endothermic reaction
Exothermic reaction: a reaction that transfers energy to the surroundings, with a negative enthalpy change. Endothermic reaction: a reaction that takes energy from the surroundings, with a positive enthalpy change.
Homogeneous catalyst vs Heterogeneous catalyst
Homogeneous catalyst: a catalyst in the same physical state as the reactants. Heterogeneous catalyst: a catalyst in a different physical state from the reactants.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by the molar gas volume?
Model answer
It is the volume occupied by one mole of any gas under stated conditions of temperature and pressure.
- 2
State the value of the molar gas volume at room temperature and pressure.
Model answer
It is 24.0 dm³ mol⁻¹.
- 3
Why does one mole of any gas occupy the same volume at a given temperature and pressure?
Model answer
The molecules themselves take up a negligible fraction of the space, so the volume depends on how many molecules are present rather than on what they are.
- 4
Calculate the volume occupied by 0.250 mol of carbon dioxide at RTP.
Model answer
The volume is 0.250 × 24.0 = 6.00 dm³.
- 5
What amount of gas, in moles, is present in 720 cm³ of oxygen at RTP?
Model answer
720 cm³ is 0.720 dm³, so the amount is 0.720 ÷ 24.0 = 0.0300 mol.
- 6
Give the ideal gas equation and say what each symbol represents.
Model answer
The equation is pV = nRT, where p is the pressure, V the volume, n the amount of gas in moles, R the gas constant and T the absolute temperature.
What is inside Levo
Six ways to work the same material.
Developing Fuels revision questions
- What does Developing Fuels cover in OCR A-Level Chemistry B?
- 24 subtopics: molar gas volume and the ideal gas equation, gas volume calculations and measuring a gas in the laboratory, bonding and shape in organic molecules, enthalpy changes: definitions and standard conditions, bond enthalpies, q = mcδt and measuring an enthalpy change in solution, burning a fuel, correcting for heat loss, and the assumptions made, hess' law and enthalpy cycles, catalysts, heterogeneous catalysis and catalyst poisons, cracking and how it is carried out, the pollutants from burning fuels and their effects, catalytic converters and cutting emissions, aliphatic and aromatic compounds, functional groups and general formulae, deducing formulae and naming a branched compound, combustion of organic compounds, addition of bromine and hydrogen halides, and the test for unsaturation, hydrogenation and hydration of alkenes, addition polymerisation, electrophilic addition mechanism, displayed, shortened and skeletal formulae, chain, position and functional group isomerism, why alkenes show stereoisomerism, and the e/z and cis/trans rules, naming and comparing the stereoisomers and sustainable fuels: benefits and risks. Each one has its own page with questions and model answers.
- How is Developing Fuels organised?
- By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Developing Fuels, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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