How the Unit 6 practical paper works

The paper

• Time and marks: 1 hour 20 minutes, 50 marks.
• Weighting: 20% of the International A2 (IA2), 10% of the full International A level.
• Question types: short-open, open-response and calculation questions, with at least 6 marks of Level 2 maths.
• Content: practical techniques from Units 4 and 5 (Core Practicals 9 to 16), plus the tests for anions, cations, gases and organic functional groups from Units 1 and 2.
• First assessed in June 2020; sat in January, June and October.

What the questions look like

A typical paper (January 2022) had four questions:

1. Inorganic analysis: complete a table of observations and inferences for an unknown salt, then suggest its formula.

2. Organic analysis: molecular formula from percentage composition and a mass spectrum, then deduce a structure from test results and IR data.

3. Titration and kinetics: make a standard solution, calculate the formula of a salt from a redox titration, then describe a continuous monitoring method and read rates from tangents.

4. Melting temperature: describe the procedure and what impurities do.

Questions are mostly 'describe', 'explain', 'justify', 'deduce' and 'calculate', and some ask for labelled diagrams or work drawn on a graph.

What examiners reward

From the October 2024 report:

• Read the question and use the information given: calculate a concentration from the data rather than reading it roughly from a graph.
• Set out calculations clearly and do not round part-way.
• Learn technical terms (a burette is not the biuret test).
• Practise drawing apparatus, such as filtration under reduced pressure.
• Know how a method is carried out, not only the theory: knowing that pH = pKa at half-neutralisation is not enough if you cannot describe how to get a half-neutralised solution.

Worked example

In an analysis table, a student adds aqueous sodium hydroxide to solution Y and sees a green precipitate that turns brown at the surface on standing. Write the observation and inference correctly.

1. Observation (what is seen): green precipitate, turning brown on standing in air.
2. Inference (what it shows): Fe2+ ions are present; the precipitate is Fe(OH)2, which is oxidised by air to Fe(OH)3.

Answer: Observation: green ppt turning brown. Inference: Fe2+ (Fe(OH)2 oxidised to Fe(OH)3).

Check yourself

1. How long is the Unit 6 paper?
   • 1 hour 45 minutes
   • 2 hours
   • 50 minutes
   • 1 hour 20 minutes
   Show answer

   1 hour 20 minutes. It is 1 h 20 min for 50 marks, like Unit 3.

2. What percentage of the International A2 (IA2) is Unit 6 worth?
   • 10%
   • 20%
   • 30%
   • 40%
   Show answer

   20%. 20% of the IA2 and 10% of the full A level.

3. Which tests can appear on the Unit 6 paper as well as the A2 techniques?
   • Only tests for transition metal ions
   • No qualitative tests
   • Only the flame tests
   • The anion, cation, gas and organic group tests from Units 1 and 2
   Show answer

   The anion, cation, gas and organic group tests from Units 1 and 2. The specification says Unit 6 also assesses the Unit 1 and 2 tests.

4. Which entry belongs in the 'observation' column of an analysis table?
   • Off-white precipitate that darkens on standing
   • Mn2+ ions present
   • Manganese(II) hydroxide forms
   • The solid is a transition metal compound
   Show answer

   Off-white precipitate that darkens on standing. Observations are what you see; the others are inferences.

5. A student wants to find pKa for a weak acid with a pH meter. Which method is correct?
   • Put the pH meter in the mixture at the end point
   • Measure the pH of the alkali before the titration
   • Measure the pH when exactly half of the acid has been neutralised
   • Measure the pH after adding a large excess of alkali
   Show answer

   Measure the pH when exactly half of the acid has been neutralised. At the end point all the acid is neutralised; at half-neutralisation [HA] = [A-], so pH = pKa.

6. Give two pieces of advice from examiners for the Unit 6 paper.
   Show answer

   Use the information given in the question, and set out calculations clearly without rounding part-way (also: learn technical terms, practise drawing apparatus).. These come straight from recent examiners' reports.

Practise with instant feedback Print this lesson

Sources

• Pearson Edexcel IAL Chemistry (2018) specification
• Pearson IAL Chemistry teacher practical guide
• Pearson examiners' report, WCH16 October 2024
• Pearson WCH16 January 2022 question paper (unused)

Last updated 8 November 2026. Spotted a mistake? Tell us.