Diesel and petrol engines can also produce smoke and soot. The amount of smoke produced depends on the efficiency of the engine. Smoke absorbed into the lungs can cause disease. Fractional Distillation Air is separated by fractional distillation. The following are removed before cooling water vapour carbon dioxide polluting gases such as SO 2 polluting solids such as smoke and dust particles.
Nitrogen comes off as the first fraction, oxygen is second.
Oxygen is used in large amounts for steel making in welding and cutting to assist people with breathing difficulties. Nitrogen is used to make ammonia for fertiliser to keep food fresh by filling packaging with N 2 instead of air. The noble gases are extremely unreactive monatomic gases. Their electronic structure provides a key to understanding the way all other elements react. Neon is used in advertising signs to give a red light.