You will complete 12 required Specified Practical Activities if you are studying GCSE Chemistry, and 27 if you are studying GCSE Combined Science (nine of these are in Chemistry). These help you develop some key practical techniques in Chemistry.
You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
There are two Specified Practical Activities in the 'Pure substances and mixtures' section:
Questions courtesy of Eduqas.
Chromatography can be used to test if racehorses have been given drugs. Urine samples from four horses, A-D, were tested to find out whether they contained caffeine or paracetamol.
The following diagram shows the results obtained.
Explain how the results show that none of the horses had been given caffeine. [1 mark]
There are no caffeine 'spots' present in any of the urine samples from the horses. 
The diagrams show three methods, A, B and C, used to separate mixtures.
The names of the separation methods and some of the pieces of apparatus used are given in the list below.
Choose the answers to parts a) and b) from the list.
a) In method C, name the apparatus labelled X. [1 mark]
b) Give the name of method B. [1 mark]
a) Condenser 
b) Chromatography 
The diagram shows the apparatus which can be used to separate a mixture of ethanol and water. Ethanol has a boiling point of 78°C.
Compound X has a boiling point of 75°C.
a) Suggest why this method would not be very effective in separating compound X and ethanol. [2 marks]
b) Suggest how you could adapt the method to improve the separation of compound X and ethanol. [1 mark]
a) Only a small difference between boiling points. 
A large amount of ethanol vapour would also reach the condenser at the boiling point of compound X/75 °C. 
b) Add a fractionating column.