Process
Edexcel A-Level Chemistry 9CH0
Atomic Structure and the Periodic Table
Bonding and Structure
Inorganic Chemistry and the Periodic Table
Topic overviewFlame tests and how they workThermal decomposition of nitrates and carbonatesCarrying out flame tests and testing the gasesGroup 2 elements and their compoundsTrends in Group 7 and predicting fluorine and astatineHalogen displacement reactionsDisproportionation and the reactions of chlorineHalides with concentrated sulfuric acid, and the hydrogen halidesTesting for halide ions with silver nitrateTesting for carbonate and hydrogencarbonate ionsTesting for sulfate and ammonium ions
Formulae, Equations and Amounts of Substance
Topic overviewThe mole, molar mass and empirical formulaThe ideal gas equation and molar volumeEquations, concentration and reacting quantitiesStandard solutions, titration and uncertaintyPercentage yield, atom economy and acid reactionsCore practicals 1 to 3Empirical formula and water of crystallisation by experimentApparatus, uncertainty and mathematical skills
Organic Chemistry I
Topic overviewFormulae, homologous series and functional groupsIUPAC nomenclatureTypes of organic reaction and structural isomerismStereoisomerism and E/Z nomenclaturePractical techniques in organic chemistryAlkanes, crude oil and combustion pollutantsRadical substitutionAlkenes, the double bond and hydrogenationElectrophilic addition, Markovnikov's rule and the test for an alkeneAddition polymers and waste polymersNucleophilic substitution of halogenoalkanesRates of hydrolysis and the SN1 and SN2 mechanismsClassifying and oxidising alcoholsAlcohols: practical techniques and the core practicals
Modern Analytical Techniques I
Energetics I
Kinetics I
Equilibrium I
Acid-Base Equilibria
Energetics II
Redox II
Transition Metals
Topic overviewElectron configuration and what makes a transition metalComplex ions, ligands and the colour of transition metal ionsCoordination number, monodentate ligands and the shapes of complexesBidentate and multidentate ligands, and ligand exchangeVanadium and chromium chemistryReactions with sodium hydroxide and ammoniaCobalt and copper complexesLigand exchange, amphoteric behaviour and the chelate effectTransition metals as catalysts
Kinetics II
Organic Chemistry II
Topic overviewChiralityAldehydes, ketones and their oxidationReduction and nucleophilic addition of HCNTesting for a carbonyl group: 2,4-DNPH and the iodoform reactionCarboxylic acids and their reactionsEsters and acyl chloridesReflux, extraction and recrystallisationDistillation, melting temperature and working safely
Organic Chemistry III
Topic overviewThe structure of benzene and the evidence for itElectrophilic substitution of benzeneNitration, halogenation, Friedel-Crafts and phenolAmines: structure and basicityReactions of amines and preparing themAmides and condensation polymersAmino acids, zwitterions and proteinsEmpirical and molecular formulae from analytical dataGrignard reagents and multi-step synthesisPurification techniques and the aspirin preparation
Equilibrium I
The equilibrium constant Kc
- 4 things to know
- Papers 1 and 3
Overview
What Kc describes, writing Kc expressions from equilibrium concentrations, including for N₂(g) + 3H₂(g) ⇌ 2NH₃(g), leaving pure solids and liquids out of heterogeneous equilibria, and working out the units of Kc.
What you need to know
Answer each one before you reveal it.
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Numbers
For the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g), write the Kc expression.
Key term
What does the equilibrium constant Kc describe?
Key term
For the reaction aA + bB ⇌ cC + dD, write the expression for Kc.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does the equilibrium constant Kc describe?
Model answer
The ratio of the concentrations of products to reactants at equilibrium, each raised to the power of its balancing number.
- 2
For the reaction aA + bB ⇌ cC + dD, write the expression for Kc.
Model answer
Kc = [C]ᶜ[D]ᵈ / ([A]ᵃ[B]ᵇ), using equilibrium concentrations.
- 3
What concentrations are used in the Kc expression?
Model answer
The concentrations of the species at equilibrium.
- 4
In a heterogeneous equilibrium, which species are left out of the Kc expression?
Model answer
Pure solids and pure liquids.
- 5
For the equilibrium N₂(g) + 3H₂(g) ⇌ 2NH₃(g), write the Kc expression.
Model answer
Kc = [NH₃]² / ([N₂][H₂]³).
- 6
Why can a solid be omitted from the Kc expression?
Model answer
Its concentration is effectively constant and is incorporated into the value of Kc.
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