The Haber process is used to make ammonia, NH3.
N2 + 3H2 ⇌ 2NH3
The reaction reaches a dynamic equilibrium.
i) What happens to the rate of the forward and backward reactions at dynamic equilibrium?
[1]
ii) What happens to the concentrations of the reacting substances at equilibrium?
[1]
Ammonia is used to make fertilisers.
Fertilisers usually contain nitrogen.
Name the two other elements that fertilisers usually contain. ........................................ and ..........................................
Ammonium sulfate is a salt used as a fertiliser.
Ammonium sulfate can be made in a laboratory in a batch process.
Ammonia solution is titrated with dilute sulfuric acid to make a solution of ammonium sulfate, as shown in the diagram.

Describe how you would make dry crystals of ammonium sulfate from ammonium sulfate solution.
Calcium sulfate is another salt.
A student made some calcium sulfate.
Look at the method he used:
pour 100 cm3 of calcium nitrate solution into a beaker
add drops of sodium sulfate solution until a precipitate appears
allow the precipitate to settle to the bottom of the beaker
pour off the liquid
use a spatula to transfer the solid calcium sulfate onto a piece of filter paper.
Describe and explain two ways that the student could improve his method to increase the amount of pure, dry calcium sulfate made.
1 ........................................................
2 ........................................................
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