Ammonia

Uses

The Properties of Ammonia

Haber Process
Ammonia is commercially produced by the Haber Process. This is a flow chart to show the stages in the manufacture of ammonia, starting with the raw materials.

Ammonium Fertilisers
examples of ammonium fertilisers:

• Ammonium phosphate
• Ammonium nitrate
• Ammonium sulphate

The Effectiveness of Ammonium Fertilisers

It could be measured through determining its percentage of nitrogen content.  Plants needs nitrogens to grow.  Usually nitrogen is absorbed by plants in soluble nitrate ions from soils. Ammonium fertilisers consist of ammonium ions. Bacteria in the soils convert ammonium ions into nitrate ions which absorbed by plants together with water.  fFertiliser with higher percentage of nitrogen content is more effective.

To determine nitrogen content in ammonium fertilizer,

Comparison of Common Fertilizers

Fertiliser	Ammonium Sulphate, (NH4)2SO4	Ammonium Nitrate, NH4NO3
Molar mass	(14+(1)4)2+32+(16)4=132	14+(1)4+14+(16)3=80
Percentage of nitrogen in 1 mol	16/132 x 100% = 12.121%	28/80 x 100% = 35%

You should calculate the percentage of nitrogen content in each fertiliser and compare which one has higher percentage of nitrogen content. You'll know which fertiliser from the list is more effective.
From this example, ammonium nitrate is more effective.

Preparation of Ammonium Nitrate
Aim: To prepare ammonium nitrate
Material: 1 mol dm^-3 ammonia solution, NH3

Material : 1 mol dm^-3 ammonia solution, NH₃(aq), 1 mol dm^-3 nitric acid, NO₃, red litmus paper.

Apparatus : 250 cm³ beaker, glass rod, tripod stand, Bunsen burner, wire gauze, filter funnel, filter                                  paper, measuring cylinder, dropper, asbestos tile.

Procedure :

1.     Measure 50 cm³ of 1 mol dm^-3 nitric acid, HNO₃, with a measuring cylinder and pour into a 250 cm³ beaker.

2.     Add 1 mol dm^-3 ammonia solution, NH₃ (aq), drop by drop from a dropper into the nitric acid, HNO₃, while stirring until an excess amount is used (when ammonia is smelt).

3.     Pour the mixture into an evaporating dish.

4.     Boil the mixture until it evaporates to form a saturated solution.

5.     Cool the saturated solution to room temperature until crystal salts form.

6.     Filter and rinse the crystals with a little cold distilled water.

7.     Dry the salt crystals on a filter paper.

Analysis : Neutralisation occurs between nitric acid, HNO₃, and ammonia solution, NH₃(aq), and can                          be represented by the chemical equation below:

2NH₃(aq)   +   HNO₃   -->   NH₄NO₃

Conclusion : Ammonium nitrate, NH₄NO₃, salt can be prepared from the reaction between nitric acid,                               HNO₃, and ammonia solution, NH₃(aq).

Discussion :

1.     The mixture formed in the beaker can be tested from time to time with red litmus paper. The adding of ammonia solution, NH₃(aq), drops are stopped when the red litmus paper turns blue.

2.     The chemical equation of the reaction between ammonia aqueous solution and nitric acid, HNO₃, can be written as below:

HNO₃(aq)   +   2NH₄OH(aq)   -->   NH₄NO₃(aq)   +   2H₂O(l)

However, only about 2% of the dissolved ammonia forms ammonium and hydroxide ions.

References

-Longman Essential Chemistry SPM