Ammonium sulfate and ammonium nitrate are two common compounds that are used as fertilisers. They are both easy to make in the lab by carrying out a simple neutralisation reaction. Word and symbolic equations for the neutralisation reaction that can be used to prepare ammonium sulfate are shown below:

ammonium hydroxide_(aq) + sulfuric acid_(aq) → ammonium sulfate_(aq) + water_(l)

2NH₄OH_(aq) + H₂SO_4(aq) → (NH₄)₂SO_4(aq) + H₂O_(l)

Making ammonium sulfate by neutralisation using ammonium hydroxide solution

Instrctions for making ammonium sulfate crystals

• Step 1. - to make a salt called a sulfate you must use sulfuric acid.


• Step 2.- a few drops of methyl orange indicator are added to the sulfuric acid. Methyl orange indicator is red in acid and yellow in neutral/alkaline solutions.


• Step 3.-To neutralise the sulfuric acid slowly add; with constant stirring the alkaline ammonium hydroxide solution. The sulfuric acid will have been neutralised when the indicator jus turns yellow.


• Step 4. - The indicator; in this case methyl orange; is a coloured dye and must be removed otherwise the final crystals of ammonium sulfate will be covered in the coloured indicator. Now charcoal is good at removing smells, stains and odours. So simply add a few spatulas full of powdered charcoal and stir for a few minutes to remove the methyl orange indicator from the solution.


• Step 5 - The charcoal needs to be removed from the solution now. This is easily done by simple filtration.


• Step 6 - Heat the salt solution over a water bath until approximately 75% of the solution has evaporated.


• Step 7 - Place the remaining salt solution on an evaporating basin and leave in a warm sunny spot to allow the remaining water to evaporate and the ammonium sulfate crystals to grow.

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