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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 9 – pH Titration Curve: Weak Acid with Strong Base

Aim:
To investigate how the pH of a solution of ethanoic acid changes as sodium hydroxide is added.

Overview:
Calibrate a pH meter, then titrate ethanoic acid with sodium hydroxide while recording pH to produce and interpret a weak acid–strong base titration curve.

See pH Curves for more background theory.

Part 1: Calibrate the pH Meter

Apparatus and Reagents:

Method Summary

AQA A-Level Chemistry pH meter calibration with buffers at pH 4.00, 7.00 and 9.20, rinsing the probe between readings and plotting a calibration graph.
  1. Rinse the probe, place in pH 7.00 buffer, and record the reading.
  2. Repeat with pH 4.00 and 9.20 buffers, rinsing between each.
  3. Plot measured pH readings (x-axis) vs true buffer pH (y-axis) to generate a calibration graph.

Part 2: Measure the pH of the Acid–Base Mixture

Apparatus and Reagents:

Method Summary

AQA A-Level Chemistry titration setup with two burettes (ethanoic acid and sodium hydroxide), a pH probe in a beaker, and incremental additions around the equivalence point.
  1. Rinse and fill one burette with ethanoic acid, the other with NaOH.
  2. Use 20.0 cm3 of ethanoic acid in a clean beaker.
  3. Insert the pH probe and stir gently.
  4. Add NaOH in 2.0 cm3 portions, record pH after each.
    When 18 cm3 NaOH has been added, use 0.20 cm3 additions up to 22.0 cm3.
    Then return to 2.0 cm3 additions until 40.0 cm3 total NaOH is added.
  5. Rinse the probe when finished.

Data Analysis

Safety Notes