Making fertilisers
Ammonium The substance formed when the hydrogen ion in an acid is replaced by a metal ion. are sources of Able to dissolve in solvent. For example, sugar is soluble in water because it dissolves to form sugar solution. nitrogen, so they can be used as ânitrogenousâ A nutrient added to the soil to increase the soil fertility.. They are manufactured on an industrial scale, but they can also be made in the laboratory on a smaller scale.
Ammonium nitrate, NH4NO3, and ammonium sulfate, (NH4)2SO4, are two nitrogenous fertilisers.
Making ammonium sulfate in the lab
Ammonium sulfate can be made in the lab using dilute ammonia solution and dilute sulfuric acid:
ammonia + sulfuric acid â ammonium sulfate
2NH3(aq) + H2SO4(aq) â (NH4)2SO4(aq)
Both A substance that reacts together with another substance to form products during a chemical reaction. are soluble, so A quantitative procedure in which two solutions react in a known ratio, so if the concentration of one solution is known and the volumes of both are measured, the concentration of the other solution can be determined. must be used.
A simple method
Here is an outline of one way to make ammonium sulfate in the lab. Eye protection must be worn.
- Put some dilute sulfuric acid into a beaker.
- Add a few drops of methyl orange A substance that has different colours, depending upon the pH of the solution it is in..
- Add dilute ammonia solution drop by drop, stirring in between.
- Continue step 3 until the colour permanently changes from red to yellow.
- Add a few more drops of dilute ammonia solution.
- Pour the reaction mixture into an evaporating basin, and heat carefully over a boiling water bath.
- Stop heating before all the water has When a liquid changes state to a gas. and leave aside for A solid containing particles (atoms, molecules or ions) joined together to form a regular arrangement or repeating pattern.to form.
- pour away excess water and leave the crystals to dry in a warm oven, or pat dry with filter paper
Question
Explain why a few more drops of dilute ammonia solution are added at step 5, after the end-point.
This is to make sure that all the dilute sulfuric acid has reacted. During heating at stage 6, any In chemistry, a substance is in excess if there is more than enough of it to react with another reactant. ammonia gas leaves the evaporating basin, so only ammonium sulfate solution is present.
The industrial production of ammonium sulfate
The industrial production of ammonium sulfate happens on a much larger scale than its production in the lab. A fertiliser factory often begins with the Basic material that goods are made from such as crops, metals, wood and animal products such as wool and leather. needed to make ammonia and sulfuric acid, rather than buying these two reactants from elsewhere. Several stages are needed.
The lab preparation of ammonium sulfate is a âbatchâ process. A small amount of product is made slowly at any one time, and the apparatus cleaned ready to make another batch.
The industrial production of ammonium sulfate is a âcontinuousâ process. The product is made quickly all the time, as long as raw materials are provided.