Energetics, Group Chemistry, Halogenoalkanes and Alcohols

Worked examples (8)

• 1Identifying the intermolecular forces present (2 marks)
• 2Explaining the boiling-temperature trend in alkanes (3 marks)
• 3Drawing a hydrogen bond between water molecules (3 marks)
• 4Comparing boiling temperatures of chain isomers (4 marks)
• 5Why ethanol boils higher than propane (4 marks)
• 6Ranking molecules by boiling temperature (5 marks)
• 7Why ice is less dense than liquid water (6 marks)
• 8Solubility and 'like dissolves like' (6 marks)

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Worked examples (8)

• 1Conditions for a successful collision (2 marks)
• 2Defining activation energy (2 marks)
• 3Why increasing concentration increases rate (3 marks)
• 4Effect of surface area on rate (3 marks)
• 5Maxwell–Boltzmann distribution and increasing temperature (5 marks)
• 6Measuring rate as 1/time (disappearing cross) (4 marks)
• 7How a catalyst increases rate using the distribution (5 marks)
• 8Why the temperature effect is not just ‘faster movement’ (6 marks)

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Worked examples (8)

• 1Heat energy released using q = mcΔT (2 marks)
• 2Classifying reactions and giving the sign of ΔH (2 marks)
• 3Writing an equation for a standard enthalpy of formation (3 marks)
• 4Enthalpy of combustion per mole from calorimetry (4 marks)
• 5Enthalpy of neutralisation from calorimetry (5 marks)
• 6Hess's Law using ΔfH data (5 marks)
• 7Hess's Law using ΔcH data (6 marks)
• 8Mean bond enthalpy calculation (6 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2 Core Practical 2
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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2

Worked examples (8)

• 1Defining oxidation and reduction (2 marks)
• 2Oxidation number of an element in a simple compound (2 marks)
• 3Oxidation number of chromium in the dichromate(VI) ion (2 marks)
• 4Identifying what is oxidised and the oxidising agent (4 marks)
• 5Building a half-equation for manganate(VII) (4 marks)
• 6Oxidation numbers in the exceptions: H₂O₂ and NaH (3 marks)
• 7Combining half-equations into a full redox equation (6 marks)
• 8Disproportionation of chlorine in cold alkali (5 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2
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Worked examples (8)

• 1Naming and classifying a halogenoalkane (2 marks)
• 2Why the C–X bond is attacked by nucleophiles (2 marks)
• 3Nucleophilic substitution with hydroxide (4 marks)
• 4Reaction with cyanide — extending the chain (4 marks)
• 5Predicting substitution versus elimination (4 marks)
• 6Reaction with excess ammonia — two-step mechanism (5 marks)
• 7Elimination mechanism with ethanolic KOH (5 marks)
• 8CP5: rate of hydrolysis and bond enthalpy (6 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2

Worked examples (8)

• 1Reactivity trend down Group 1 (2 marks)
• 2Equation for a Group 2 metal with water (2 marks)
• 3Identifying a metal from its flame colour (2 marks)
• 4Predicting Group 2 solubility trends (3 marks)
• 5Explaining the origin of a flame colour (4 marks)
• 6Reactions of Group 1 and 2 metals with oxygen (3 marks)
• 7Thermal stability of nitrates and carbonates (6 marks)
• 8Full explanation of reactivity down Group 2 (5 marks)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2

Worked examples (8)

• 1Reading the molecular ion peak (2 marks)
• 2Identifying a fragment from a mass loss (2 marks)
• 3Identifying a functional group from an IR absorption (2 marks)
• 4Interpreting a chlorine M/M+2 pattern (4 marks)
• 5Distinguishing propanal from propanone (4 marks)
• 6Confirming oxidation of an alcohol from IR (4 marks)
• 7Deducing a structure from mass + IR data (6 marks)
• 8Bromine isotope pattern and identification (6 marks)

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Worked examples (8)

• 1Colours and states of the halogens (3 marks)
• 2Identifying a halide from silver nitrate + ammonia (2 marks)
• 3Predicting a halogen displacement reaction (2 marks)
• 4Explaining the boiling temperature trend (3 marks)
• 5Oxidising power down Group 7 with displacement evidence (4 marks)
• 6Concentrated sulfuric acid with NaCl vs NaBr (4 marks)
• 7Concentrated sulfuric acid with sodium iodide (6 marks)
• 8Disproportionation of chlorine and water treatment (6 marks)

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Worked examples (8)

• 1Features of a dynamic equilibrium (3 marks)
• 2Effect of adding a reactant (2 marks)
• 3Effect of a catalyst on equilibrium (2 marks)
• 4Effect of temperature on an exothermic equilibrium (4 marks)
• 5Effect of pressure — counting gas moles (4 marks)
• 6Why 450 °C in the Haber process (5 marks)
• 7Justifying the Contact process conditions (6 marks)
• 8Applying Le Chatelier to an unfamiliar equilibrium (6 marks)

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Worked examples (8)

• 1Naming functional groups and series (3 marks)
• 2Classifying reactions by type (3 marks)
• 3Nucleophile, electrophile and radical (3 marks)
• 4Bond polarity and where a nucleophile attacks (4 marks)
• 5Curly arrows for a heterolytic step (4 marks)
• 6Empirical, molecular and structural formulae (4 marks)
• 7Assigning E/Z with CIP priorities (5 marks)
• 8Homolytic vs heterolytic fission with curly arrows (6 marks)

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Worked examples (8)

• 1Naming and classifying alcohols (2 marks)
• 2Oxidation products of 1°, 2° and 3° alcohols (3 marks)
• 3Distillation vs reflux for oxidising a primary alcohol (4 marks)
• 4Distinguishing an aldehyde from a ketone (4 marks)
• 5Dehydration of an alcohol to an alkene (4 marks)
• 6Identifying alcohol class from oxidation behaviour (5 marks)
• 7Esterification and the ester product (5 marks)
• 8CP6: preparing and purifying a halogenoalkane (6 marks)

Model answers (9)

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• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2
• ✓Model answer — Adapted from Edexcel IAL Chemistry Unit 2 (Core Practical 6)