Practical questions
You will complete eight Practical Activity Groups (PAGs) if you are studying GCSE Chemistry. If you are studying GCSE Combined Science you will complete 16, of which five are in Chemistry.
You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
There are two PAGs in the Chemical reactions section:
- Electrolysis, eg electrolysis of aqueous sodium chloride or aqueous copper sulfate solution
- Production of salts, eg production of pure dry sample of a salt
Learn about practicals with Dr Alex Lathbridge
Listen to the full series on 大象传媒 Sounds.
Dr Alex Lathbridge answers questions about practicals.
Sample question 1 - Foundation
Question
Sodium chloride solution is made by reacting sodium hydroxide solution with dilute hydrochloric acid. State one safety precaution that must be taken when using these solutions.
[1 mark]
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
Any one precaution from:
- wear gloves to prevent contact with skin/safety [1]
- wear spectacles to prevent contact with eyes [1]
Sample question 2 - Higher
Question
Electrolysis is carried out on copper sulfate solution using copper electrodes.
The change in mass at each electrode is measured before and during electrolysis using this method:
- Use a balance to measure the mass of the copper cathode and copper anode.
- Set up the apparatus and run the electrolysis for 30 seconds.
- Remove the electrodes. Immediately place them on the balance and measure their masses again.
What improvements could you make to this method? Explain your answers.
[4 marks]
OCR Gateway Science, GCE Chemistry, Paper J248, 2016 - Higher.
- electrolysis needs to run for longer than 30 seconds [1]
- otherwise insufficient change at electrodes [1]
- after electrolysis anode and cathode need to be washed [1]
- and then dried [1] before measuring the mass [1]