Practical questions
You will complete eight required core practical activities if you are studying GCSE Chemistry, and 18 if you are studying GCSE Combined Science (five of these are in Chemistry).
You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
There are two core practical activities in the Separate Chemistry 2 section:
- identify the ions in unknown salts
- investigate the temperature rise produced in a known mass of water by the combustion of alcohols
Edexcel questions courtesy of Pearson Education Ltd.
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Dr Alex Lathbridge answers questions about practicals.
Sample question 1 – Foundation
Question
The temperature rise in water when liquid fuels burn can be found using the equipment shown in the diagram.
A student compares the temperature rise produced in the water when propanol burns with the temperature rise produced when ethanol burns.
State two factors that the student must keep the same in both experiments in order to have a fair comparison.
[2 marks]
Any two from:
- mass/volume of water [1]
- height of container above wick [1]
- length of wick/height of flame [1]
- the container needs to be the same shape/size/material [1]
- same number of moles of alcohol [1]
Sample question 2 – Foundation
Question
Sodium hydroxide solution is warmed with a solution of ammonium ions.
Ammonia gas is given off.
Describe the test to show the gas is ammonia.
[2 marks]
- Test gas with damp red litmus paper [1]
- Paper turns blue [1]
Sample question 3 – Higher
Question
A student carries out a flame test on an unknown solid. A red flame is seen.
The student concludes that the solid is lithium carbonate.
Explain why this conclusion is not justified.
[2 marks]
- The red flame test shows the presence of calcium ions/Ca2+ and not lithium ions/Li+ [1]
- The student did not test for carbonate ions/CO32- [1]
Sample question 4 – Higher
Question
Sodium hydroxide solution is also used to distinguish between iron(II) ions, Fe2+ and iron(III) ions, Fe3+, in solution.
You are given a solution containing iron(II) ions and another solution containing iron(III) ions.
Describe what is seen when sodium hydroxide solution is added to each of these solutions.
[2 marks]
- Iron(II) – green precipitate/solid [1]
- Iron(III) – red-brown/brown precipitate/solid [1]
