Topic - Ammonia

HOW TO OBTAIN AMMONIA - THE HABER PROCESS

• The raw materials for this process are hydrogen and nitrogen. Hydrogen is obtained by reacting natural gas - methane - with steam, or through the cracking of oil. Nitrogen is obtained by burning hydrogen in air. Air is 80 per cent nitrogen; nearly all the rest is oxygen. When hydrogen is burned in air, the oxygen combines with the hydrogen, leaving nitrogen behind.
• Nitrogen and hydrogen will react together under these conditions:
• • a high temperature - about 450ºC
  • a high pressure - about 200 atmospheres (200 times normal pressure)
  • an iron catalyst

• The reaction is reversible.
• nitrogen + hydrogen = ammonia

• N2(g) + 3H2(g) = 2NH3(g)
• The (g) indicates that the substance is a gas.
• The flow chart shows the main stages in the Haber process. The reaction is reversible, and some nitrogen and hydrogen remain mixed with the ammonia. The reaction mixture is cooled so that the ammonia liquefies and can be removed. The remaining nitrogen and hydrogen are recycled.

PROPERTIES OF AMMONIA

• colourless gas with sharp smell
• lighter than air
• very soluble in water; the resulting solution contains ammonium and hydroxide ions
• an alkaline gas - turns damp red litmus blue, due to its hydroxide ions
• puts out a burning splint - won't burn in air…