colourless gas at room temperature and pressure
Melting point -169oC
Boiling point -104oC
slightly sweet smell
soluble in non-polar solvents & insoluble in polar solvents like water
reactive: the active site is the double bond
Readily undergoes addition reactions, for example
reacts with bromine water (red-brown) to produce colourless 1,2-dibromoethane
CH2=CH2(g) + Br2(l) -----> CH2Br-CH2Br(g)
Production of Styrene
styrene can be polymerised to form polystyrene
Production of chloroethane
chloroethane is used to manufacture tetraethyl lead
tetraethyl lead is the lead additive in leaded petrol
CH2=CH2 + HCl
Ethene is also used as a plant hormone to control the ripening and colour development of fruit
Production of Ethene (ethylene)
Ethene can be produced either by
Extraction from natural gas using fractional distillation followed by steam cracking (the technique for converting alkanes to alkenes)(750 - 900oC) followed by liquefaction of the gas (-100oC) and then further fractional distillation
Extraction from crude oil using fractional distillation followed by steam cracking (750 - 900oC) of the naphtha or gas-oil fractions followed by liquefaction of the gas (-100oC) and then further fractional distillation.
The cracking process typically involves endothermic equilibrium reactions such as:
increasing the temperature of the reactions favours the formation of products since the reactions are endothermic. So increasing the temperature speeds up the rate of the reaction and increases the yield of ethene.
a decrease in pressure would favour the the formation of products since there are more gaseous product molecules than there are gaseous reactant molecules. However, a decrease in pressure would slow down the rate of the reaction. For this reason the pressure is kept at or below atmospheric pressure.
removing the product will favour the formation of more product thereby increasing the yield of product. Equilibrium is therefore never actually achieved.