Numbers
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
Acid-Base Equilibria
Buffers in blood, and the core practical
- 3 things to know
- Papers 1 and 3
Overview
How the carbonic acid and hydrogencarbonate buffer holds blood near pH 7.4, Core Practical 9 finding Kₐ from the pH of a weak acid of known concentration, ways of measuring pH, the role of indicators, and decimal places, calculator functions and logarithms in pH calculations.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What are the products when carbonic acid in blood reacts with added hydroxide ions?
Key term
In the blood buffer system, which species acts as the weak acid and which acts as the conjugate base?
Questions from this subtopic
Each one with the model answer underneath.
- 1
At what pH is blood normally maintained?
Model answer
Approximately pH 7.4.
- 2
In the blood buffer system, which species acts as the weak acid and which acts as the conjugate base?
Model answer
Carbonic acid (H₂CO₃) acts as the weak acid; hydrogencarbonate ions (HCO₃⁻) act as the conjugate base.
- 3
Explain how the blood buffer system responds when hydrogen ions are added.
Model answer
Hydrogencarbonate ions react with H⁺ to form carbonic acid, which then decomposes to carbon dioxide and water.
- 4
Describe the reaction that occurs in blood when hydroxide ions are added, involving the carbonic acid buffer system.
Model answer
Carbonic acid reacts with the hydroxide ions to form hydrogencarbonate ions and water, neutralising the added base
- 5
What are the products when carbonic acid in blood reacts with added hydroxide ions?
Model answer
Hydrogencarbonate ions (HCO₃⁻) and water
- 6
What is the purpose of Core Practical 9?
Model answer
To obtain Kₐ: make up a weak acid at a concentration you know, then measure its pH.
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