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
The Chemical Industry
- 16 subtopics
- 43 things to know
- Components 01, 02 and 03
What The Chemical Industry covers
The storyline that carries kinetics and the quantitative treatment of equilibrium: rate equations and orders, half-lives, the Arrhenius equation, the rate-determining step, what changes an equilibrium constant, and the chemistry and economics of an industrial process.
Where it is assessed
Components 01, 02 and 03
Storyline content, drawn on by all three written papers.
Check the OCR specification ↗The 16 subtopics
Each one has its own page.
- Rate equations, order and the rate constantRecall questions on the definition of rate and its units, what order means, and why the orders cannot be read off the balanced equation.Open →
- Deducing the units of k and rate calculationsRecall questions on working out the units of k for each overall order, and calculating a rate or a concentration from a rate equation.Open →
- Half-livesRecall questions on which order has a constant half-life, how successive half-lives behave for each order, and k = ln 2 / t½.Open →
- Continuous monitoring, quenching and the initial rates methodRecall questions on the three experimental approaches, using a colorimeter, and why the initial rate is the one measured.Open →
- Reading order from concentration-time and rate-concentration graphsRecall questions on the shapes for each order on both kinds of graph, drawing a tangent, and what a linear gradient gives.Open →
- The Arrhenius equation and what each symbol meansRecall questions on the exponential and logarithmic forms, what Ea, A, R and T each represent, and why k rises steeply with temperature.Open →
- The ln k against 1/T plot and finding the activation enthalpyRecall questions on which quantities are plotted, what the gradient and intercept give, and calculating Ea and A from them.Open →
- Rate-determining step and mechanismRecall questions on what the rate-determining step is, what the orders imply about which species take part, and testing a proposed mechanism.Open →
- Effect of conditions on the magnitude of the equilibrium constantRecall questions on why only temperature changes Kc, what heating does to an exothermic and an endothermic reaction, and what a catalyst does not do.Open →
- Economic operating conditions for an industrial processRecall questions on balancing yield against rate, why very high pressure is not always used, and why a catalyst sets a lower temperature limit.Open →
- Writing a Kc expression and deducing its unitsRecall questions on homogeneous equilibria, writing the expression from a balanced equation, and deducing the units for each case.Open →
- ICE-table calculations and measuring Kc experimentallyRecall questions on using an initial, change and equilibrium table, converting amounts to concentrations, and measuring Kc for an esterification.Open →
- Chemical reactions in industrial processesRecall questions on the stages of nitric and sulfuric acid manufacture, why oleum is made, and the green case for a carbonylation route.Open →
- Nitrogen, ammonia and the ammonium ionRecall questions on why nitrogen is unreactive, the shape and bond angle of ammonia and of the ammonium ion, and how the dative bond forms.Open →
- Oxidation states of nitrogen and the tests for nitrate and ammoniumRecall questions on the oxidation state of nitrogen in its oxides and ions, and the Devarda's alloy and hydroxide tests.Open →
- Costs, benefits and risks of industrial processesRecall questions on saleable co-products, the double cost of a by-product, energy recovery, plant capacity and location.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What is the overall order, and what happens to the rate when a zero-order and a first-order concentration are changed?
Numbers
What does doubling a second-order concentration do, and what are the units of k for zero and first order overall?
Numbers
Which order has a half-life independent of concentration, how do successive half-lives show first-order kinetics, and how do they behave for zero order?
Numbers
How do successive half-lives behave for second order, and how are the half-life and the rate constant related for a first-order reaction?
Evaluation
What concentration remains 150 s after a first-order reaction starts at 0.80 mol dm⁻³ with t½ = 50 s, why should more than one half-life be measured, and how long until 87.5% of a first-order reactant with t½ = 4.0 min has gone?
Key term
What is the symbol used for half-life?
Numbers
What is continuous monitoring, how is a colorimeter used, and what is the quenching method for?
Numbers
Why is a thermostatted water bath used, why is the initial rate measured, and how is a rate read off a curve?
Numbers
Why must a tangent be used rather than a chord, why is the gradient of a concentration–time graph negative while the rate is positive, and how is first order recognised from the graph?
Numbers
Doubling [A] quadruples the rate, while trebling [B] leaves it unchanged. Write the rate equation.
Numbers
What is the straight-line form of the Arrhenius equation, what does each symbol mean, and what is the gas constant?
Numbers
Why does k rise steeply with temperature, what does a larger activation enthalpy do, and which quantities are plotted?
Numbers
What is A when the intercept ln A is 24.0, what temperature does 1/T = 3.20 × 10⁻³ K⁻¹ correspond to, and how does a ln k against 1/T plot show k rising with temperature?
Numbers
What is the rate-determining step, how many particles take part up to it when rate = k[A]²[B], and which species are involved in it when A + 2B + C → products has rate = k[A][B]?
Process
A reaction is found to be zero order with respect to one reactant. What does this reveal about the mechanism?
Process
Why is a step involving three particles colliding at once considered unlikely?
Process
Can kinetic evidence ever prove a mechanism is correct?
Process
Which single condition changes Kc, and what happens to it on heating an exothermic and an endothermic reaction?
Numbers
What do a catalyst and a change of concentration each do to the magnitude of Kc and to the position of equilibrium?
Numbers
How does Kc change when the exothermic ammonia equilibrium is cooled, and what do a very large and a very small Kc indicate?
Process
Explain why quoting a value of Kc without a temperature is meaningless.
Evaluation
Which two chemical considerations are balanced when choosing conditions, why is very high pressure not always used, and why do many catalysts set a lower limit on the operating temperature?
Numbers
What is meant by recycling unreacted feedstock, and why is it done?
Numbers
Given data showing that yield rises only slightly between 200 and 400 atmospheres, what would you conclude?
Key term
What role does the physical state of a catalyst play in plant design?
Numbers
What is a homogeneous equilibrium, what is the general Kc expression, and what are the units for the dinitrogen tetroxide equilibrium?
Numbers
What are the units of Kc for the hydrogen iodide, sulfur trioxide and ammonia equilibria?
Numbers
When does Kc have no units, how is the change in amount fixed by the stoichiometry, and why is the flask volume not needed to find Kc for ethanoic acid + ethanol ⇌ ethyl ethanoate + water?
Key term
When Kc is measured experimentally, why must the reaction mixture be left for a long time before it is sampled?
Numbers
What are the oxidation states of nitrogen in NO and NO₂, why is 3NO₂ + H₂O → 2HNO₃ + NO a disproportionation, and which stage of S + O₂ → SO₂ then 2SO₂ + O₂ ⇌ 2SO₃ is an equilibrium?
Evaluation
Why is sulfur trioxide absorbed in concentrated sulfuric acid rather than water, what happens when the oleum is diluted, and why is making ethanoic acid by CH₃OH + CO → CH₃COOH attractive on green grounds?
Key term
Why is nitrogen gas unreactive, what are the shape and bond angle of ammonia, and how is the ammonium ion formed?
Key term
Why are all four N-H bonds in the ammonium ion identical, and what is the oxidation state of nitrogen in N₂O and NO₂?
Key term
What are the oxidation states of nitrogen in the nitrate(V) ion, the nitrate(III) ion and the ammonium ion?
Numbers
How does a saleable co-product improve the economics of a process, why is an unwanted by-product a double cost, and how does raising the yield from 60% to 75% change the raw material needed?
Process
Why is energy recovery designed into a chemical plant, why does running below design capacity raise the cost per tonne, and how does the location of a plant affect its costs?
Evaluation
Why is the transport of a chemical sometimes riskier than its manufacture?
Evaluation
Why can the hazard of a substance never be reduced by a change in working practice, whereas the risk can?
Numbers
State the usual units of rate of reaction.
Numbers
Write the Arrhenius equation in its exponential form.
Numbers
Nitrogen monoxide is oxidised by 2NO + O₂ → 2NO₂. Give the oxidation state of nitrogen in each oxide.
Key term
Describe the shape and bond angle of an ammonia molecule.
Take The Chemical Industry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Rate constant vs Order of reaction
Rate constant: the proportionality constant in a rate equation, which changes only with temperature. Order of reaction: the power to which a concentration is raised in the rate equation.
Rate-determining step vs Activation enthalpy
Rate-determining step: the slowest step in a mechanism, which fixes the overall rate. Activation enthalpy: the minimum energy needed by colliding particles for a reaction to occur.
Zero-order reactant vs First-order reactant
Zero-order reactant: a reactant whose concentration has no effect on the rate. First-order reactant: a reactant for which doubling the concentration doubles the rate.
Questions from this topic
Each one with the model answer underneath.
- 1
Define the rate of a chemical reaction.
Model answer
The rate of reaction is the change in concentration of a reactant or product divided by the time taken for that change.
- 2
State the usual units of rate of reaction.
Model answer
The usual units are mol dm⁻³ s⁻¹.
- 3
What is a rate equation?
Model answer
A rate equation is an expression showing how the rate depends on the concentrations of the species that affect it, of the form rate = k[A]ᵐ[B]ⁿ.
- 4
Can the orders in a rate equation be predicted from the balanced equation?
Model answer
No, orders can only be found by experiment, because they depend on the mechanism rather than on the overall stoichiometry.
- 5
Define the order of reaction with respect to a given reagent.
Model answer
It is the power to which the concentration of that reagent is raised in the experimentally determined rate equation.
- 6
Define the overall order of a reaction.
Model answer
The overall order is the sum of the individual orders with respect to each species in the rate equation.
What is inside Levo
Six ways to work the same material.
The Chemical Industry revision questions
- What does The Chemical Industry cover in OCR A-Level Chemistry B?
- 16 subtopics: rate equations, order and the rate constant, deducing the units of k and rate calculations, half-lives, continuous monitoring, quenching and the initial rates method, reading order from concentration-time and rate-concentration graphs, the arrhenius equation and what each symbol means, the ln k against 1/t plot and finding the activation enthalpy, rate-determining step and mechanism, effect of conditions on the magnitude of the equilibrium constant, economic operating conditions for an industrial process, writing a kc expression and deducing its units, ice-table calculations and measuring kc experimentally, chemical reactions in industrial processes, nitrogen, ammonia and the ammonium ion, oxidation states of nitrogen and the tests for nitrate and ammonium and costs, benefits and risks of industrial processes. Each one has its own page with questions and model answers.
- How is The Chemical Industry organised?
- By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in The Chemical Industry, 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.