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

1. Nitrogen for growth of stems and leaves

2. Phosphorus for healthy root growth

3. Potassium for flower and fruit formation

4. 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