Key term
Eduqas A-Level Chemistry A410QS
Formulae and Equations
Basic Ideas About Atoms
Topic overviewRadioactive decay and nuclear equationsBehaviour of α, β and γ radiationHalf-life and radioactive decay calculationsRadiation hazards and the uses of radioisotopesIonisation energy and its variation between elementsSuccessive ionisation energies and electronic structureOrbitals and electron configurations of elements 1 to 36Emission and absorption spectraThe hydrogen spectrum, E = hf and the convergence limit
Chemical Calculations
Topic overviewRelative atomic, isotopic, formula and molecular massPrinciples of the mass spectrometerMass spectra, isotopic abundance and relative atomic massEmpirical and molecular formulaeThe mole, the Avogadro constant and molar massMoles, grams and numbers of particlesConcentration and solubilityMolar volume and gas volume correctionsThe ideal gas equationStoichiometry and reacting quantitiesAcid-base titration calculationsAtom economy, percentage yield and percentage error
Bonding
Solid Structures
The Periodic Table
Topic overviewArrangement of the elements and the s-, p- and d-blocksOxidation and reduction as electron transferTrends across periods and down groupsReactions of Group 2 elements with oxygen, water and steamReactions of the aqueous cations Mg²⁺, Ca²⁺ and Ba²⁺Flame coloursReactivity of Group 1 and Group 2 metalsThermal stability of the Group 2 carbonates and hydroxidesSolubility of the Group 2 hydroxides and sulfatesBasic character of the Group 1 and Group 2 oxides and hydroxidesVolatility of the halogens and their reactions with metalsOxidising power, displacement reactions and the silver nitrate testWater treatment, salt preparation and gravimetric analysis
Simple Equilibria and Acid-Base Reactions
Thermochemistry
Rates of Reaction
The Wider Impact of Chemistry
Organic Compounds
Hydrocarbons
Topic overviewAlkanes and the sigma-bonded frameworkCombustion of alkanes and the use of fossil fuelsFree radical substitution and the photochlorination of alkanesAlkenes and the reactivity of the C=C bondE–Z isomerismElectrophilic addition of bromine to alkenesTests for alkenesMarkovnikov addition of hydrogen bromide and carbocation stabilityCatalytic hydrogenation of alkenesAddition polymerisation
Halogenoalkanes
Topic overviewNucleophilic substitution of primary halogenoalkanesElimination reactions forming alkenesBond polarity, bond enthalpy and the ease of substitutionThe silver nitrate test for halogenoalkanesUses of halogenoalkanes and the regulation of their useCFCs and their effect in the upper atmosphereHeating under reflux
Alcohols and Carboxylic Acids
Topic overviewIndustrial preparation of ethanol from etheneFermentation and the distillation of ethanolBiofuels and the issues they raiseClassifying alcohols as primary, secondary and tertiaryDehydration of alcohols to alkenesOxidation of primary alcohols to aldehydes and carboxylic acidsOxidation of secondary alcohols to ketonesThe dichromate(VI) test for alcoholsCarboxylic acids and the sodium hydrogencarbonate testReactions of carboxylic acids with bases, carbonates and hydrogencarbonatesEsterification and separation by distillation
Instrumental Analysis
Redox and Standard Electrode Potential
Redox Reactions
Chemistry of the P-Block
Topic overviewAmphoteric behaviour of aluminium and leadThe inert pair effect in Groups 3, 4 and 5Electron-deficient compounds and expanded octetsAl₂Cl₆ and donor-acceptor compoundsHexagonal and cubic boron nitrideStability of oxidation states II and IV in Group 4Carbon dioxide and lead(II) oxideBonding in the Group 4 chloridesHydrolysis of the Group 4 chloridesReactions of aqueous lead(II) ionsChlorine with cold and warm aqueous sodium hydroxideBleaching and bactericidal action of chlorine and chlorate(I)Sodium halides with concentrated sulfuric acid
Chemistry of the D-Block Transition Metals
Topic overviewOxidation states of the d-block elementsImportant oxidation states and the colours of aqueous ionsBonding in tetrahedral and octahedral complexesThe origin of colour and the splitting of d-orbitalsLigand exchange and change of coordination numberColours and formulae of copper and cobalt complex ionsHeterogeneous and homogeneous catalysisNickel in hydrogenation and iron in the Haber processVanadium(V) oxide and manganese(IV) oxide as catalystsReactions of Cr³⁺, Fe²⁺, Fe³⁺ and Cu²⁺ with excess aqueous hydroxide
Chemical Kinetics
Enthalpy Changes for Solids and Solutions
Entropy and Feasibility of Reactions
Equilibrium Constants
Acid-Base Equilibria
Topic overviewThe Lowry–Brønsted theory and conjugate pairsStrong and weak acids and the dissociation constant KaThe ionic product of water, KwpH of strong acids and strong basespH of weak acids from Ka and pKaTitration curvesHow buffer solutions workBuffer calculationsBuffers in living systems and industrySalt hydrolysis and the choice of indicator
Stereoisomerism
Aromaticity
Alcohols and Phenols
Aldehydes and Ketones
Topic overviewPreparing aldehydes and ketones by oxidation of alcoholsDistinguishing aldehydes and ketones with Tollens’ reagent and Fehling’s solutionReduction of aldehydes and ketones using NaBH₄Nucleophilic addition of HCN to aldehydes and ketonesReaction with 2,4-dinitrophenylhydrazineThe triiodomethane (iodoform) test
Carboxylic Acids and Their Derivatives
Topic overviewRelative acidity of carboxylic acids, phenols, alcohols and waterPreparing carboxylic acids by oxidationReduction and decarboxylation of carboxylic acidsAcid chlorides and their reactionsEsters and their hydrolysisAmides and their hydrolysisNitriles from carboxylic acids and halogenoalkanesHydroxynitriles, hydrolysis and reduction of nitriles
Amines
Amino Acids, Peptides and Proteins
Organic Synthesis and Analysis
Topic overviewPlanning a multi-step synthesisChoosing between alternative routesManipulation and separation techniquesPurification and melting temperatureAddition and condensation polymerisationPolyesters and polyamidesHigh resolution proton NMRCombining spectra to elucidate a structureInterpreting chromatographic dataGas chromatography and HPLC
Specified Practical Work
Topic overviewGravimetric analysis and qualitative analysis of unknown solutionsStandard solutions, standardising an acid and preparing a soluble saltBack titration and double titrationDetermining enthalpy changes by calorimetryFollowing a rate by gas collection, the iodine clock and reaction orderElectrochemical cells, redox titration and the estimation of copperDetermining an equilibrium constant and following a titration with a pH probeHydrolysis of 1-bromobutane and the preparation of an esterOrganic synthesis, purification and identification
Practical Skills and Techniques
Topic overviewChoosing apparatus and recording measurementsVolumetric technique with pipette, burette and volumetric flaskTitration procedure and the choice of indicatorHeating, heating under reflux and distillationFiltration, purification and qualitative testingMelting temperature, chromatography and electrochemical cellsVariables, errors and risk in evaluating a method
Mathematical Skills in Chemistry
Topic overviewStandard form, units and significant figuresRatios, fractions and percentagesChanging the subject and substituting valuesLogarithms, pH and pKaExponentials, the Arrhenius equation and rateGraphs, gradients and interceptsTangents and rates of changeArea under a curveUncertainty and combining errorsThe gas equation and equilibrium expressions
Equilibrium Constants
- 4 subtopics
- 12 things to know
- Component 1
What Equilibrium Constants covers
Equilibrium Constants is examined in Component 1, Physical and Inorganic Chemistry, and drawn on again in Component 3. It covers writing Kc and Kp expressions and their units, Calculating Kc and the amounts present at equilibrium, Kp, partial pressures and mole fractions and temperature and the magnitude of the equilibrium constant.
Where it is assessed
Component 1
Physical and Inorganic Chemistry, and drawn on again in Component 3.
Check the Eduqas specification ↗The 4 subtopics
Each one has its own page.
- Writing Kc and Kp expressions and their unitsRecall questions on which quantities go in the numerator, writing Kc from a balanced equation, deducing units by cancelling, writing Kp in terms of partial pressures, what a heterogeneous equilibrium is and which species are omitted, and worked expressions for named equilibria.Open →
- Calculating Kc and the amounts present at equilibriumRecall questions on the initial, change and equilibrium layout, why the changes follow the balancing numbers, converting moles to concentrations and when the volume cancels, worked calculations of Kc from initial amounts, and working back from Kc to an equilibrium amount.Open →
- Kp, partial pressures and mole fractionsPartial pressure of a gas in a mixture, mole fraction of a gas in a mixture and how a partial pressure is calculated from a mole fraction.Open →
- Temperature and the magnitude of the equilibrium constantRecall questions on the effect of raising the temperature on the constant of an exothermic and of an endothermic reaction, why concentration, pressure and a catalyst leave it unchanged, what large and small values indicate, and the relationship between the forward and reverse constants.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
How is Kc worked out from initial amounts, and when does the volume cancel?
Key term
In a Kc expression, which quantities are placed in the numerator?
Key term
State how a partial pressure is calculated from a mole fraction.
Key term
Write the Kc expression for N₂(g) + 3H₂(g) ⇌ 2NH₃(g).
Key term
Which three quantities are tabulated for each species when Kc is worked out from initial amounts?
Key term
What is the sum of all the partial pressures in a gas mixture?
Key term
Describe the effect on the equilibrium constant of raising the temperature of an exothermic reaction.
Key term
Deduce the units of Kc for the equilibrium PCl₅(g) ⇌ PCl₃(g) + Cl₂(g).
Key term
Why must amounts in moles be converted into concentrations before being used in a Kc expression?
Numbers
An equilibrium mixture contains 0.600 mol of N₂O₄ and 0.800 mol of NO₂ at a total pressure of 1.00 atm. Calculate the two partial pressures.
Key term
Describe the effect on the equilibrium constant of raising the temperature of an endothermic reaction.
Take Equilibrium Constants further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
In a Kc expression, which quantities are placed in the numerator?
Model answer
The equilibrium concentrations of the products, each raised to the power of its coefficient in the balanced equation.
- 2
Write the Kc expression for N₂(g) + 3H₂(g) ⇌ 2NH₃(g).
Model answer
Kc = [NH₃]² ÷ ([N₂][H₂]³).
- 3
Deduce the units of Kc for the equilibrium PCl₅(g) ⇌ PCl₃(g) + Cl₂(g).
Model answer
Two concentration terms on top and one below leave one unit uncancelled, so Kc has units of mol dm⁻³.
- 4
Write the Kc expression for H₂(g) + I₂(g) ⇌ 2HI(g) and state its units.
Model answer
Kc = [HI]² ÷ ([H₂][I₂]), and it has no units because the concentration terms cancel.
- 5
Write the Kp expression for N₂(g) + 3H₂(g) ⇌ 2NH₃(g).
Model answer
Kp = p(NH₃)² ÷ (p(N₂) × p(H₂)³).
- 6
Deduce the units of Kp for N₂(g) + 3H₂(g) ⇌ 2NH₃(g) when pressures are measured in atmospheres.
Model answer
The units are atm² ÷ atm⁴, which simplifies to atm⁻².
What is inside Levo
Six ways to work the same material.
Equilibrium Constants revision questions
- What does Equilibrium Constants cover in Eduqas A-Level Chemistry?
- 4 subtopics: writing kc and kp expressions and their units, calculating kc and the amounts present at equilibrium, kp, partial pressures and mole fractions and temperature and the magnitude of the equilibrium constant. Each one has its own page with questions and model answers.
- How is Equilibrium Constants organised?
- By the Eduqas A410QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Equilibrium Constants, 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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