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
What's in a Medicine?
- 17 subtopics
- 39 things to know
- Components 01, 02 and 03
What What's in a Medicine? covers
The storyline that carries the oxygen-containing functional groups and the practical organic work: alcohols and phenols and their reactions, preparing and purifying a solid and a liquid product, green chemistry, elimination, and identifying a compound by mass spectrometry and infrared.
Where it is assessed
Components 01, 02 and 03
Storyline content, drawn on by all three written papers.
Check the OCR specification ↗The 17 subtopics
Each one has its own page.
- Formulae of oxygen-containing homologous seriesRecall questions on the functional groups and general formulae of carboxylic acids, esters, anhydrides, aldehydes and ketones.Open →
- Primary, secondary and tertiary alcoholsRecall questions on what defines each class, how many hydrogens sit on the hydroxyl carbon, and classifying a named alcohol.Open →
- The acidity of phenol compared with alcohols and carboxylic acidsRecall questions on why phenol is a stronger acid than an alcohol but weaker than a carboxylic acid, and its reaction with sodium hydroxide.Open →
- The iron(III) chloride test and esterifying a phenolRecall questions on the neutral iron(III) chloride test, and why a phenol needs an anhydride or acyl chloride rather than a carboxylic acid.Open →
- Esterification and oxidising primary, secondary and tertiary alcoholsRecall questions on the acid-catalysed ester equilibrium, the dichromate colour change, and what distillation and reflux each give from a primary alcohol.Open →
- Dehydration, halogenation and planning a two-step synthesisRecall questions on the conditions for dehydration and for making a haloalkane, and on the order of steps in a two-step route.Open →
- Preparing aspirin, filtering under reduced pressure and recrystallisationRecall questions on the aspirin preparation, Buchner filtration, and each stage of a recrystallisation and why it is done that way.Open →
- Thin layer chromatography, Rf values and percentage yieldRecall questions on the TLC plate and tank, locating colourless spots, calculating an Rf value, and why a recrystallised yield is low.Open →
- Reflux and distillation in an organic preparationRecall questions on what reflux achieves, anti-bumping granules, why the apparatus is never sealed, and where the thermometer bulb sits in a distillation.Open →
- Washing, drying and redistilling a liquid productRecall questions on using a separating funnel, washing with sodium hydrogencarbonate, choosing and removing a drying agent, and why the product is redistilled.Open →
- The aims of green chemistry and atom economyRecall questions on preventing rather than treating waste, the atom economy expression, and why it differs from percentage yield.Open →
- Catalysts, renewable feedstocks and measuring greennessRecall questions on why a catalytic route is greener, renewable feedstocks, co-products against by-products, and what can actually be measured.Open →
- Elimination reactionsRecall questions on what is lost and what is formed, dehydrating an alcohol, why two alkenes can result, and eliminating from a haloalkane.Open →
- The molecular ion and fragment ionsRecall questions on what the horizontal axis shows, what the molecular ion peak gives, and why fragment peaks appear below it.Open →
- Identifying a compound from its fragments and the M+1 peakRecall questions on the common fragment masses, working a structure out from a spectrum, and what causes the M+1 peak.Open →
- How infrared absorption works and the characteristic absorptionsRecall questions on why each bond absorbs at its own wavenumber, and the ranges for O-H, C=O, C≡N, N-H and C=C.Open →
- Reading a spectrum, the fingerprint region and combining techniquesRecall questions on identifying a compound from its absorptions, following an oxidation by infrared, and why infrared is combined with other techniques.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What is the molecular formula of ethanoic anhydride, and what are the general structure and formula of an ester?
Numbers
To which homologous series do ethyl methanoate and propanoic acid belong, where must an aldehyde group sit in the chain, and what is the general formula of a saturated aldehyde?
Key term
How many oxygen atoms does each of an aldehyde, an ester and an acid anhydride functional group contain?
Key term
What defines a primary, a secondary and a tertiary alcohol?
Key term
How many hydrogens are on the carbon bearing the OH group in a secondary alcohol, and how are butan-1-ol and butan-2-ol classified?
Key term
How is 2-methylpropan-2-ol classified, why is 2-methylpropan-1-ol still primary, and why is methanol a special case?
Numbers
Is phenol acidic in water, why is it a stronger acid than an alcohol, and what is its equation with sodium hydroxide?
Numbers
What is seen when phenol is added to sodium carbonate, which reagents does a carboxylic acid react with that a phenol does not, and what is the equation for ethanoic acid with sodium carbonate?
Key term
Which reagent converts a phenol into an ester, why can a carboxylic acid not do it directly, and what is formed from phenol and ethanoic anhydride?
Numbers
What is the equation for ethanol with ethanoic acid, why is it reversible, and what does ethanoic anhydride give instead?
Key term
What oxidising mixture is used on alcohols, what colour change is seen, and which ion causes the green colour?
Numbers
What forms when a primary alcohol is refluxed with excess acidified dichromate, and what are the equations using [O]?
Process
Explain why a tertiary alcohol is not oxidised by acidified dichromate(VI).
Key term
What is observed when phosphorus(V) chloride is added to a dry alcohol?
Numbers
What catalyst is used in the aspirin preparation, how should a recrystallisation solvent treat impurities, and what are the TLC phases?
Numbers
Why is a TLC baseline drawn in pencil, how are colourless spots located, and how far does a spot with Rf 0.65 travel when the solvent front moves 12.0 cm?
Numbers
Why must a reference sample share the plate, what do two spots on crude aspirin mean, and why is the yield low?
Process
Explain why an Rf value can never be greater than 1.
Key term
Which two organic reagents are used to prepare aspirin in the laboratory?
Evaluation
What is heating under reflux, why is a heating mantle preferred to a Bunsen, and how do you identify the aqueous layer?
Key term
Why is a separating funnel vented, what is seen when washing with sodium hydrogencarbonate, and which solids dry an organic liquid?
Process
How do you know enough drying agent has been added, how is it removed, and what is Quickfit apparatus?
Evaluation
Give two advantages of working at reduced scale in an organic preparation.
Numbers
Is preventing waste or treating it preferable, what is atom economy, and how does it differ from percentage yield?
Numbers
What percentage of the reactant mass ends up as product at 80% atom economy and 75% yield, why is a catalytic route greener, and why is energy use itself a green chemistry concern?
Key term
What is a renewable feedstock, what is an example, and what is the difference between a co-product and a by-product?
Numbers
State two measures of greenness that can be calculated directly from an equation and a mass of product.
Key term
How many organic products come from each molecule in an elimination, what bond is created, and what is lost in dehydration?
Numbers
What is the equation for dehydrating ethanol, from which atoms are the pieces lost, and why can butan-2-ol give two alkenes?
Numbers
Which alkene comes from dehydrating propan-1-ol, how does elimination compare with addition, and what is eliminated from 2-bromopropane with hot ethanolic potassium hydroxide?
Numbers
What is plotted on the horizontal axis of a mass spectrum, why is it effectively a mass scale, and what is the molecular ion?
Process
Why do peaks appear below the molecular ion, why can no fragment ion appear above it, and why is only one piece of a fragmentation detected?
Numbers
Which ion gives m/z 15, what does a ketone at 58 and 43 tell you, and what is lost from ethanoic acid to give 45?
Numbers
In the aspirin spectrum a peak at m/z 120 follows the one at 138. What neutral molecule has been lost?
Numbers
What is plotted on each axis of an infrared spectrum, and how are the O-H absorptions of an alcohol and an acid told apart?
Numbers
What are the wavenumber ranges of the C=O bond in an ester, a ketone and an aldehyde?
Numbers
What do an absorption at 1745 cm⁻¹ and a broad one from 2500 to 3300 cm⁻¹ indicate, and how does the infrared spectrum change as ethanol is oxidised to ethanoic acid?
Numbers
What quantity is plotted along the horizontal axis of an infrared spectrum?
Take What's in a Medicine? further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Primary alcohol vs Secondary alcohol
Primary alcohol: an alcohol whose hydroxyl carbon carries two hydrogen atoms. Secondary alcohol: an alcohol whose hydroxyl carbon carries one hydrogen atom.
Oxidation under distillation vs Oxidation under reflux
Oxidation under distillation: conditions that remove an aldehyde as it forms, stopping further oxidation. Oxidation under reflux: conditions that return vapour to the flask so oxidation continues to the acid.
Elimination vs Substitution
Elimination: a reaction in which a small molecule is lost and a multiple bond is formed. Substitution: a reaction in which one atom or group replaces another.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the functional group of a carboxylic acid?
Model answer
The carboxyl group, –COOH, in which a carbonyl and a hydroxyl group are joined to the same carbon atom.
- 2
Give the general molecular formula of a saturated aliphatic carboxylic acid with one –COOH group.
Model answer
The general formula is CₙH₂ₙO₂.
- 3
Write the structural formula of ethanoic acid.
Model answer
Ethanoic acid is CH₃COOH.
- 4
What structural feature defines a phenol?
Model answer
A phenol has an –OH group bonded directly to a carbon atom of a benzene ring.
- 5
Give the molecular formula of the simplest phenol.
Model answer
The simplest phenol is C₆H₅OH, molecular formula C₆H₆O.
- 6
Why is 2-phenylethanol not classed as a phenol?
Model answer
Its –OH group is attached to a saturated carbon of a side chain rather than directly to the ring, so it is an alcohol.
What is inside Levo
Six ways to work the same material.
What's in a Medicine? revision questions
- What does What's in a Medicine? cover in OCR A-Level Chemistry B?
- 17 subtopics: formulae of oxygen-containing homologous series, primary, secondary and tertiary alcohols, the acidity of phenol compared with alcohols and carboxylic acids, the iron(iii) chloride test and esterifying a phenol, esterification and oxidising primary, secondary and tertiary alcohols, dehydration, halogenation and planning a two-step synthesis, preparing aspirin, filtering under reduced pressure and recrystallisation, thin layer chromatography, rf values and percentage yield, reflux and distillation in an organic preparation, washing, drying and redistilling a liquid product, the aims of green chemistry and atom economy, catalysts, renewable feedstocks and measuring greenness, elimination reactions, the molecular ion and fragment ions, identifying a compound from its fragments and the m+1 peak, how infrared absorption works and the characteristic absorptions and reading a spectrum, the fingerprint region and combining techniques. Each one has its own page with questions and model answers.
- How is What's in a Medicine? organised?
- By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in What's in a Medicine?, 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.
Or £46 a year, about £3.83 a month. Cancel anytime.