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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
- 5 subtopics
- 15 things to know
- Papers 1 and 3
What Acid-Base Equilibria covers
Covers the Brønsted-Lowry definitions and the pH scale, strong and weak acids with Ka and Kw, pH calculations and titration curves, and buffers including the ones that hold blood pH steady.
Where it is assessed
Papers 1 and 3
Advanced Inorganic and Physical Chemistry, then the synoptic paper.
Check the Pearson Edexcel specification ↗The 5 subtopics
Each one has its own page.
- Bronsted-Lowry acids and bases, and the pH scaleRecall questions on proton transfer and conjugate pairs, on the definition of pH, and on converting between pH and hydrogen ion concentration.Open →
- Strong and weak acids, Ka and KwRecall questions on full and partial dissociation, on writing Ka and pKa, and on the ionic product of water and its role in alkali calculations.Open →
- Calculating pH, and titration curvesRecall questions on the pH of strong and weak acids and of alkalis, on the effect of dilution, and on the four titration curve shapes and their indicators.Open →
- Buffer solutions and the Henderson-Hasselbalch equationAcidic and basic buffers and how an acidic buffer removes added H⁺ and OH⁻ ions, the Henderson–Hasselbalch equation, why pH equals pKₐ at half-equivalence so Kₐ can be read from a titration curve, and why a weak acid gives a less exothermic enthalpy of neutralisation.Open →
- Buffers in blood, and the core practicalHow 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.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
How does an acidic buffer resist a change in pH?
Numbers
Once hydrogen ion concentration is known, how is pH calculated?
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For a strong monoprotic acid, what is the relationship between hydrogen ion concentration and acid concentration?
Numbers
At what pH is blood normally maintained?
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What are the products when carbonic acid in blood reacts with added hydroxide ions?
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What is transferred between species during an acid-base reaction?
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Dilute a strong acid tenfold — how far does the pH move?
Numbers
State the expression used to calculate Kₐ from the measured pH and initial concentration of a weak acid.
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Define a buffer solution.
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What is a conjugate acid-base pair?
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What does it mean for an acid to be described as strong?
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What quantities are plotted on the axes of a titration curve?
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What components make up an acidic buffer?
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In the blood buffer system, which species acts as the weak acid and which acts as the conjugate base?
Take Acid-Base Equilibria further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Brønsted–Lowry acid vs Brønsted–Lowry base
Brønsted–Lowry acid: species donating a proton. Brønsted–Lowry base: species accepting a proton.
Strong acid vs Weak acid
Strong acid: proton donor fully dissociated in water. Weak acid: proton donor only partially dissociated in water.
Equivalence point vs End point
Equivalence point: the stage at which reactants have reacted in exact stoichiometric amounts. End point: the stage at which an indicator changes colour.
Questions from this topic
Each one with the model answer underneath.
- 1
Define a Brønsted–Lowry acid.
Model answer
On the Brønsted–Lowry definition, an acid gives away H⁺.
- 2
Define a Brønsted–Lowry base.
Model answer
On the Brønsted–Lowry definition, a base takes up H⁺.
- 3
What is transferred between species during an acid-base reaction?
Model answer
Protons (H⁺ ions) are transferred from the acid to the base.
- 4
What is a conjugate acid-base pair?
Model answer
A conjugate acid-base pair consists of two species that differ by exactly one proton; the conjugate acid has one more proton than its conjugate base.
- 5
What forms when an acid donates a proton?
Model answer
The acid forms its conjugate base.
- 6
What forms when a base accepts a proton?
Model answer
The base forms its conjugate acid.
What is inside Levo
Six ways to work the same material.
Acid-Base Equilibria revision questions
- What does Acid-Base Equilibria cover in Edexcel A-Level Chemistry?
- 5 subtopics: bronsted-lowry acids and bases, and the ph scale, strong and weak acids, ka and kw, calculating ph, and titration curves, buffer solutions and the henderson-hasselbalch equation and buffers in blood, and the core practical. Each one has its own page with questions and model answers.
- How is Acid-Base Equilibria organised?
- By the Edexcel 9CH0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Acid-Base Equilibria, 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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