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*Revision Materials and Past Papers* 1 Atomic Structure 2 Amounts of Substance 3 Bonding 4 Energetics 5 Kinetics 6 Chemical Equilibria & Kc 7 Redox Equations 8 Thermodynamics 9 Rate Equations 10 Kp (Equilibrium Constant) 11 Electrode Potentials & Cells 12 Acids and Bases 13 Periodicity 14 Group 2: Alkaline Earth Metals 15 Group 7: The Halogens 16 Period 3 Elements & Oxides 17 Transition Metals 18 Reactions of Ions in Aqueous Solution 19 Intro to Organic Chemistry 20 Alkanes 21 Halogenoalkanes 22 Alkenes 23 Alcohols 24 Organic Analysis 25 Optical Isomerism 26 Aldehydes & Ketones 27 Carboxylic Acids & Derivatives 28 Aromatic Chemistry 29 Amines 30 Polymers 31 Amino Acids, Proteins & DNA 32 Organic Synthesis 33 NMR Spectroscopy 34 Chromatography RP1–RP12 Required Practicals

7.2 Required Practicals

1 Make up a volumetric solution and carry out a simple acid–base titration 2 Measurement of an enthalpy change 3 Investigation of how the rate of a reaction changes with temperature 4 Carry out simple test-tube reactions to identify cations anions 5 Distillation of a product from a reaction 6 Tests for alcohol, aldehyde, alkene and carboxylic acid 7 Measuring the rate of reaction, by an initial rate method, by a continuous monitoring method 8 Measuring the EMF of an electrochemical cell 9 Investigate how pH changes when a weak acid reacts with a strong base and when a strong acid reacts with a weak base 10 Preparation of, a pure organic solid and test of its purity, a pure organic liquid 11 Carry out simple test-tube reactions to identify transition metal ions in aqueous solution 12 Separation of species by thin-layer chromatography

Disclaimer:
The exact reagents, reactions, processes and equipment used in practical activities may vary between schools, colleges, and exam board exemplar methods. The essential techniques, skills, and learning objectives remain the same. Always follow the instructions, risk assessments, and safety guidance provided by your teacher or centre.


PRACTICAL 10 – Organic Preparations

Part A: Preparation of an Organic Solid – Aspirin

Aim:
To prepare a sample of aspirin (acetylsalicylic acid) by reacting salicylic acid with ethanoic anhydride, purify it by recrystallisation, and determine its purity by melting point analysis.

Overview:
Synthesize aspirin, purify by recrystallisation, then analyse purity by melting point.

Reaction Equation

C7H6O3 + (CH3CO)2O → C9H8O4 + CH3COOH

Apparatus and Chemicals

Method – Synthesis

AQA A-Level Chemistry aspirin preparation setup using salicylic acid, ethanoic anhydride, sulfuric acid catalyst, and water bath.
  1. Weigh ~6.00 g salicylic acid into a conical flask.
  2. Add 10 cm3 ethanoic anhydride and swirl.
  3. Carefully add 5 drops of concentrated sulfuric acid.
  4. Warm mixture in a hot water bath (~60 °C) for 20 min.
  5. Cool, then pour into 75 cm3 cold water and stir to precipitate aspirin.
  6. Filter using reduced pressure, wash with cold water, dry product.

Method – Recrystallisation

AQA A-Level Chemistry recrystallisation of aspirin from ethanol and water, followed by cooling and filtration.
  1. Dissolve crude aspirin in 15 cm3 warm ethanol.
  2. Add 40 cm3 warm distilled water, allow to cool.
  3. Leave to crystallise (ice bath may be used).
  4. Filter and dry purified crystals under reduced pressure.

Melting Point Determination

AQA A-Level Chemistry melting point determination of aspirin using a capillary tube and melting point apparatus.
  1. Pack dry sample into a melting point tube.
  2. Heat slowly and record the melting temperature range.
  3. Pure aspirin melts sharply at ~135 °C; a wide range indicates impurities.

Calculations

Safety Notes

Part B: Preparation of a Pure Organic Liquid – Ethyl Ethanoate

Aim: To prepare ethyl ethanoate by refluxing ethanol and ethanoic acid with an acid catalyst, then separate and purify by distillation.

Reaction

CH3COOH + CH3CH2OH ⇌ CH3COOCH2CH3 + H2O

Apparatus and Chemicals

Method – Reflux (Esterification)

AQA A-Level Chemistry reflux setup with round bottom flask, condenser, ethanol, ethanoic acid, and sulfuric acid catalyst.
  1. Add 10 cm3 ethanol and 12 cm3 ethanoic acid to round bottom flask.
  2. Add 15 drops conc. sulfuric acid and anti-bumping granules.
  3. Reflux gently in a water bath for 15 min.

Method – Separation

AQA A-Level Chemistry separating funnel used to remove aqueous layer from ester after neutralisation with sodium carbonate.
  1. Cool the mixture, pour into beaker with 15 cm3 water + 4.5 g sodium carbonate.
  2. Transfer to separating funnel, vent frequently.
  3. Allow layers to separate: organic layer (top) contains ester.
  4. Remove aqueous layer, keep organic.
  5. Add drying agent (anhydrous sodium sulfate), swirl, decant ester.

Method – Distillation

AQA A-Level Chemistry distillation setup for collecting purified ethyl ethanoate fraction at ~77 °C.
  1. Add anti-bumping granules to dry ester solution.
  2. Distil, collect fraction boiling at ~77 °C.
  3. Weigh purified product to determine actual yield.

Calculations

Safety Notes