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 predicting and identifying reactions and products section. These are for GCSE Chemistry students only:
- reactivity trend, eg use of displacement reactions to identify the reaction trend of group 7 elements
- identification of species, eg identify an unknown compound using cation tests, anion tests and flame tests
Learn about practicals with Dr Alex Lathbridge
Listen to the full series on BBC Sounds.
Dr Alex Lathbridge answers questions about practicals.
Sample question 1 - Foundation
Question
A teacher adds a few drops of universal indicator solution to a big container of water.
She then adds a small piece of sodium, and a chemical reaction occurs.
The products of the reaction are hydrogen and sodium hydroxide.
Describe and explain the colour change observed in the mixture of universal indicator and water. [2 marks]
OCR Gateway Science, GCE Chemistry, Paper J248, 2016.
The colour changes from green to purple...[1]
...because water is neutral and sodium hydroxide is alkaline [1].
Sample question 2 - Higher
Question
A teacher demonstrates the reaction of potassium with water.
This is what he does:
- fills a big glass container with water
- places a transparent plastic screen between the container of water and the students
- removes a lump of potassium metal from its container
- uses a knife to cut off a pea-sized piece of potassium
- replaces the lump of potassium in its container, and fastens the lid
- places the pea-sized piece of potassium in the trough of water
a) Suggest a reason for step 2. [1 mark]
b) Suggest a reason for step 5. [1 mark]
c) Describe two observations the students would make in step 6. [2 marks]
OCR Gateway Science, GCE Chemistry, Paper J248, 2016 - Higher.
a) So that if reacting potassium leaves/jumps off the surface of the water, students will not be injured. [1]
b) To avoid the possibility of the big lump of potassium reacting with water. [1]
c) Two from:
- quickly melts to form a ball
- burns violently with sparks and a lilac flame
- reacts rapidly, often with a small explosion
[2]
