Making fertilisers in the lab
Ammonium sulfate and ammonium nitrate are two common compounds used as
fertilisers. They are both easy
to make in the lab by carrying out a simple neutralisation reaction.
The diagram below outlines how to make ammonium sulfate by carrying out a simple neutralisation
Making ammonium sulfate by neutralisation using ammonium hydroxide solution
You can alter the method above to make ammonium nitrate by simply using nitric acid instead of sulfuric in step 1.
- 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 acid. Methyl orange indicator is
red in acid and
yellow in neutral/alkaline solutions.
- To neutralise the acid slowly add,
with constant stirring, the alkaline ammonium hydroxide solution. The
will have been neutralised when the indicator jus
- step 4. - The indicator, in this case methyl orange,
is a coloured dye and must be removed, otherwise the final crystals of
ammnonium sulfate will
be covered in the coloured indicator. 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.
- step 5 - The charcoal needs to be removed from the solution now. This is easily done by
- 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.