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 no Specified Practical Activities in the 'Earth and its atmosphere' section.
Questions courtesy of Eduqas.
Limestone is made of calcium carbonate. It reacts slowly with acid rain and is gradually eaten away.
Design an experiment based on this reaction to identify which of three samples of rainwater is the most acidic. [3 marks]
One of the major consequences of sulfur dioxide emission is the formation of acid rain. Acid rain causes the pH in lakes and reservoirs to decrease.
Scientists studied the change in the pH of a reservoir between 1982 and 2005. The reservoir is in a remote part of the country and difficult to reach.
Give the letter of the equipment that you would choose to record and store the pH of the reservoir several times a day. Give a reason for your choice. [2 marks]
|B||Datalogger and pH sensor|
|B||Datalogger and pH sensor||✔|
(pH readings recorded) continuously/remotely/without someone being there/(pH) readings can be stored 
A group of pupils investigated the pH change which occurs when limestone reacts with acid rain. The group collected rain water during a rain shower.
They added limestone pieces to the rain water and recorded the pH of the mixture for 5 minutes. The data collected was then downloaded to a computer.
The graph below shows the results recorded.
a) Name the type of reaction taking place. [1 mark]
b) Limestone affects the acidity of acid rain. Describe how the graph supports this statement. [2 marks]
a) Neutralisation 
b) (adding limestone) increases the pH 
(higher the pH the) lower the acidity 
Two gas syringes, containing a total 50 cm3 of air, were connected either side of a tube containing copper wire.
The copper wire was heated strongly and the air from the syringes passed over it five times. The hot copper reacted with the oxygen in the air. The apparatus was then allowed to cool to room temperature before the volume of gas remaining in the syringes was measured.
Initial volume of air: 50 cm3
Final volume of gas: 41 cm3
a) Gases expand when heated. State why the apparatus was allowed to cool to room temperature before taking the final reading. [1 mark]
b) i) Calculate the percentage of oxygen in the air using the results from the above experiment. [2 marks]
ii) The actual percentage of oxygen in the air is 21%. Assuming no leakages in the apparatus give one possible reason why the experiment did not give this expected value. [1 mark]
c) i) Name the gas that makes up the biggest proportion of that remaining in the syringes. [1 mark]
ii) Name the very unreactive gas used to fill light bulbs that is also present in the syringes. [1 mark]
a) Allows a valid comparison of the two volumes 
b) i) Volume of oxygen = 50 - 41  = 9 cm3 
ii) Some unreacted oxygen still left in the air/the air has not been passed over the copper sufficient number of times/not enough copper to remove all the oxygen/some of the copper unreacted 
c) i) Nitrogen 
ii) Argon