Rates, Equilibria and Further Organic Chemistry

Worked examples (8)

• 1Defining lattice energy (2 marks)
• 2The sign of first and second electron affinity (3 marks)
• 3Comparing lattice energies of NaCl and KCl (3 marks)
• 4Born–Haber cycle: finding the lattice energy of NaCl (4 marks)
• 5Enthalpy of solution from lattice and hydration enthalpies (4 marks)
• 6Theoretical vs experimental lattice energy and covalent character (4 marks)
• 7Born–Haber cycle: finding the second electron affinity of oxygen (6 marks)
• 8Hydration enthalpy trend and predicting solubility (5 marks)

Model answers (9)

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Worked examples (8)

• 1Writing a rate equation and stating the overall order (2 marks)
• 2Deriving the units of the rate constant (first order) (3 marks)
• 3Deducing orders from an initial-rate table (4 marks)
• 4Calculating the rate constant with correct units (4 marks)
• 5Using constant half-life to show first order (4 marks)
• 6Deducing the rate-determining step and a mechanism (5 marks)
• 7Finding activation energy from an Arrhenius plot (6 marks)
• 8Deducing SN1 vs SN2 from kinetics (5 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1Predicting the sign of ΔSsystem (2 marks)
• 2Entropy and change of state (2 marks)
• 3Calculating ΔSsystem from standard entropies (3 marks)
• 4Calculating ΔSsurroundings with unit conversion (4 marks)
• 5Total entropy change and feasibility (4 marks)
• 6Temperature at which a reaction becomes feasible (5 marks)
• 7Why an endothermic reaction can be spontaneous (5 marks)
• 8Full feasibility calculation with unit conversions (6 marks)

Model answers (9)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4
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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4
• ✓Model answer 8
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1Naming carboxylic acids (2 marks)
• 2Reaction of a carboxylic acid with a carbonate (3 marks)
• 3Carboxylic acids as weak acids (3 marks)
• 4Distinguishing a carboxylic acid from a phenol (4 marks)
• 5Esterification: making and naming an ester (4 marks)
• 6Two preparation routes to a carboxylic acid (5 marks)
• 7Boiling temperature and solubility from hydrogen bonding (5 marks)
• 8Explaining acid strength with carboxylate stability (5 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4
• ✓Model answer 9

Worked examples (8)

• 1Writing a Kc expression with a solid omitted (2 marks)
• 2Kc expression and its units for the Haber process (3 marks)
• 3Partial pressure from mole fraction (3 marks)
• 4Calculating Kc from equilibrium concentrations (4 marks)
• 5Kc from an ICE table (5 marks)
• 6Calculating Kp from partial pressures (5 marks)
• 7Why only temperature changes K (6 marks)
• 8Linking K to total entropy and predicting extent (6 marks)

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Worked examples (8)

• 1Identifying the chiral centre in a molecule (2 marks)
• 2Deciding which molecule is chiral (2 marks)
• 3Effect of enantiomers on plane-polarised light (2 marks)
• 4Drawing a pair of enantiomers (3 marks)
• 5Optical activity and racemic mixtures (4 marks)
• 6Why HCN addition to a carbonyl gives a racemate (4 marks)
• 7Optical activity as evidence for SN1 vs SN2 (6 marks)
• 8Counting chiral centres and stereoisomers (5 marks)

Model answers (9)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4 (synoptic with halogenoalkanes)
• ✓Model answer 8
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1pH of a strong monoprotic acid (2 marks)
• 2Finding [H⁺] from a given pH (2 marks)
• 3Identifying conjugate acid–base pairs (2 marks)
• 4pH of a weak acid from Ka (4 marks)
• 5pH of a strong base using Kw (4 marks)
• 6pH of a buffer (Henderson–Hasselbalch) (4 marks)
• 7Finding Ka and pKa of a weak acid from pH — CP11 (5 marks)
• 8Titration curve and choosing an indicator (6 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4 (Core Practical 11)
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1Classifying and naming carbonyl compounds (2 marks)
• 2Why the C=O bond is attacked by nucleophiles (2 marks)
• 3Reduction products of an aldehyde and a ketone (3 marks)
• 4Distinguishing an aldehyde from a ketone (4 marks)
• 5Using 2,4-DNPH and melting temperature to identify a carbonyl (4 marks)
• 6Mechanism of HCN addition to a carbonyl (6 marks)
• 7Why HCN addition gives a racemic mixture (5 marks)
• 8The iodoform (triiodomethane) test (5 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1Naming an ester and giving its formation (2 marks)
• 2Reaction of an acyl chloride with water (2 marks)
• 3Acyl chloride + alcohol making an ester (3 marks)
• 4Acyl chloride + ammonia forming an amide (3 marks)
• 5Acyl chloride + primary amine → N-substituted amide (4 marks)
• 6Acid vs alkaline hydrolysis of an ester (5 marks)
• 7Drawing a polyester repeat unit (6 marks)
• 8Why the acyl chloride route beats the acid route; polymer hydrolysis (6 marks)

Model answers (9)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4
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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4

Worked examples (8)

• 1Number of ¹H NMR peaks from proton environments (2 marks)
• 2Calculating an Rf value (2 marks)
• 3Counting ¹³C NMR peaks (2 marks)
• 4Predicting the ¹H NMR spectrum of ethanol (4 marks)
• 5Applying the n+1 rule (4 marks)
• 6Using D₂O to identify an O–H proton (4 marks)
• 7Deducing a structure from MS + IR + ¹H NMR (6 marks)
• 8Interpreting a full ¹H NMR spectrum (6 marks)

Model answers (9)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 4
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