Ethene may be prepared in a laboratory by the following methods:

1. Preparation of ethane by cracking

Ethane gas can be prepared in a laboratory by the cracking of hydrocarbons such as kerosene or candle wax. A simple experimental set-upon for the preparation of ethane (ethylene) by cracking is shown.

Procedure:

ADVERTISEMENTS:

Place a spoonful of sand in a hard glass tube. Pour about 2ml of kerosene (C14H30) over it. Clamp this glass tube on iron stand slanting slightly with its mouth downwards. Place a few pieces of broken porcelain dish (china dish) in the middle of the tube. Heat the porcelain pieces until they become red hot. Now heat the sand soaked with kerosene (or wax) and then heat sand and porcelain pieces alternately.

The kerosene vaporizes on heating. The vapor of kerosene when passes over heated porcelain pieces undergoes cracking. The gas so formed is collected in gas jars by the downward displacement of water. This gas is mostly ethane (ethylene).

2. Preparation of ethane from ethanol(ethyl alcohol)

Ethane can also be prepared in a laboratory by heating ethanol (or ethyl alcohol) with excess of concentrated sulphuric acid atomic 160-170°C.

ADVERTISEMENTS:

C2H5OH + H2SO4 160-170°C CH2 = CH2 + H2O

Concentrated sulphuric acid acts as a dehydrating agent removes one molecule of water from ethanol molecule.