Chapter 15:Ammonia and it's uses
Nitrogen
- Major constituent of the air (78%)
- Inactive gas in comparison with oxygen
- Essential for the formation of animal and plant protein
Nitrogen Cycle
- Atmospheric nitrogen is taken into the soil as nitrates.
- It is converted into nitrates by fixing bacteria.
- These nitrates are then absorbed into plants to become protein.
- Plants are then eaten by animals forming animal protein.
- Bacteria decays this protein when plant/animal dies releasing nitrogen back into the atmosphere.
Ammonia
- Ammonia is the most important compound of nitrogen (NH3)
- It is industrially produced by the Haber process.
Habber process
Ammonia is industrially produced by the Habber process from nitrogen and hydrogen gases.
- [ ] These two gases are combined directly in a ratio of 3:1 and passed over an iron catalyst at 450°C and 200 atompshere of pressure.
- [ ] The catalyst used is the metal iron with prometers of iron oxide.
- [ ] When ammonia is produced it is liquidified and the excess is recycled.
NITROGEN + HYDROGEN ➡️AMMONIA
[ ] N2(g) + 3H2(g) ➡️3NH3(g)
[ ] This is an exothermic reaction. It is reversible with forward.
Testing for Ammonia
- IT IS THE ONLY ALKALINE GAS WHICH IS COMMON
- IT TURNS MOIST RED LITMUS PAPER BLUE.
- IT ALSO FUMES WITH HYDROGEN CLORIDE AND FORMS WHITE FUMES OF AMMONIUM CHLORIDE.
USES OF AMMONIA
- Manufacture of nitrogenous fertilizers
- Oxidized to nitric acid
- Plastics
- Artificial fibres
FERTILIZERS
- Nitrogen for growth of stems and leaves
- Phosphorus for healthy root growth
- Potassium for flower and fruit formation
- Calcium, sodium, magnesium, iron, zinc are also needed by plants in smaller amounts for healthy plant growth
Eutrophication
- This is a water pollution problem caused by nitrates being leached from farm land because of the high solubility of nitrates.
Liming soil
- Reduces nitrogen content of nitrogenous fertilizers as lime is an alkali which reacts with ammonia salts to release Ammonia gas