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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 6 – Identification of Organic Functional Groups

Aim:
To carry out test-tube reactions to identify the presence of alcohols, aldehydes, alkenes, carboxylic acids, and halogenoalkanes.

Overview:
This practical uses simple chemical tests to distinguish between key organic functional groups based on observable changes such as effervescence, colour changes, and precipitate formation.


Apparatus and Chemicals Required

Test 1 – Alcohol Test

AQA A-Level Chemistry test for alcohols using sodium metal showing effervescence from hydrogen gas
  1. Add about 1 cm3 ethanol to a dry test tube.
  2. Add a small piece of sodium metal.
  3. Observe for effervescence (hydrogen gas).
  4. Dispose of excess sodium safely in a beaker of ethanol.

Test 2 – Aldehyde Test (Fehling’s Solution)

AQA A-Level Chemistry aldehyde test using Fehling’s solution producing a brick red precipitate of copper(I) oxide
  1. Mix equal volumes of Fehling’s A and B to make a deep blue solution.
  2. Add 5 drops of Fehling’s to 1 cm3 sodium carbonate solution in a test tube with a few anti-bumping granules.
  3. Add 1 cm3 of ethanal or propanal.
  4. Warm gently for 2 minutes in a hot water bath, then allow to stand.
  5. Observe formation of red precipitate (Cu2O) indicating aldehyde.

Test 3 – Alkene Test (Unsaturation)

AQA A-Level Chemistry alkene test showing bromine water decolorisation in the presence of a C=C double bond
  1. Add 2 drops of cyclohexene to a test tube.
  2. Add 1 cm3 bromine water and shake.
  3. Decolorisation indicates presence of C=C double bond.

Test 4 – Carboxylic Acid Test

AQA A-Level Chemistry carboxylic acid test showing effervescence when acid reacts with sodium hydrogencarbonate
  1. Add a small spatula of solid sodium hydrogen carbonate to a boiling tube.
  2. Add about 2 cm3 of dilute ethanoic acid.
  3. Effervescence (CO2) confirms carboxylic acid.

Test 5 – Halogenoalkane Test

AQA A-Level Chemistry halogenoalkane test giving a cream silver bromide precipitate after alkaline hydrolysis and addition of silver nitrate
  1. Add 5 drops of 1-bromobutane to 1 cm3 sodium hydroxide in a test tube.
  2. Warm in a water bath at ~60 °C for a few minutes.
  3. Acidify with 2 cm3 dilute nitric acid.
  4. Add 1 cm3 silver nitrate solution.
  5. A cream precipitate (AgBr) indicates a bromoalkane.

Safety Notes

Observations