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 no PAGs in the Global challenges section.
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 student investigates the corrosion of two metals. He places strips of metals in some damp gases.
Look at his results:
| Copper | Iron | Lead | |
| Appearance at start | Shiny brown | Shiny silver | Shiny silver |
| Appearance after two weeks in damp oxygen | Green patches on surface | Orange-brown patches on surface | Dull and silvery |
| Appearance after two weeks in damp acidic air | Thick layer of green on surface | Lots of orange-brown flakes on surface | Black layer on surface |
| Appearance after two weeks in damp nitrogen | Shiny brown | Shiny silver | Lots of orange-brown flakes on surface |
| Appearance at start | |
| Copper | Shiny brown |
| Iron | Shiny silver |
| Lead | Shiny silver |
| Appearance after two weeks in damp oxygen | |
| Copper | Green patches on surface |
| Iron | Orange-brown patches on surface |
| Lead | Dull and silvery |
| Appearance after two weeks in damp acidic air | |
| Copper | Thick layer of green on surface |
| Iron | Lots of orange-brown flakes on surface |
| Lead | Black layer on surface |
| Appearance after two weeks in damp nitrogen | |
| Copper | Shiny brown |
| Iron | Shiny silver |
| Lead | Lots of orange-brown flakes on surface |
The student makes two conclusions:
- oxygen is needed for corrosion
- more corrosion happens in acidic air than in any other conditions
Explain whether the student is correct or not. Use evidence from the table in your answer. [2 marks]
OCR Gateway Science, GCE Chemistry, Paper B741, June 2015.
The following are vaild points that could be included in your answer. It is important that you do not bullet point your answer but write your sentences in full.
Yes, because:
- none of the metals corrode in nitrogen or in the absence of oxygen or air [1]
- all of the metals show more change in acidic air [1]
No marks if answer is no.
Sample question 2 - Higher
Question
Ammonium sulfate is a salt.
It is made using the reaction between the alkali ammonia and sulfuric acid:
2NH3 + H2SO4 → (NH4)2SO4
Describe how a sample of solid ammonium sulfate is prepared in a laboratory.
Explain why this method is not suitable to be used industrially. [4 marks]
OCR Gateway Science, GCE Chemistry, Paper J248, 2016 - Higher.
The following are vaild points that could be included in your answer. It is important that you do not bullet point your answer but write your sentences in full.
- titrate ammonia against sulfuric acid to find volumes needed for complete neutralisation [1]
- add these volumes together but without an indicator [1]
- evaporation water from the reaction mixture [1]
- burette and other apparatus not suitable for using large quantities [1]
Sample question 3 - Higher
Question
Scrap iron can be used to extract copper from solutions of copper salts. For example:
Fe + CuSO4 → Cu + FeSO4
1 tonne of scrap iron parts is added to an excess of copper sulfate solution. The theoretical yield is 1.13 tonnes of copper. The actual yield after removing and drying the copper is just under 200 kg.
Suggest two reasons why the actual yield of copper is less than the theoretical yield. [2 marks]
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
The following are vaild points that could be included in your answer. It is important that you do not bullet point your answer but write your sentences in full.
Two of the following:
- reaction incomplete/most iron atoms inside the parts
- iron was impure/copper sulfate was impure
- other unwanted/side reaction(s) occur
- copper lost during removal/drying
[2]
