In the hydration of ethene, ethanol is made by passing ethene and steam over a catalyst.

Water is added to ethene, this is known as hydration.


Catalyst: Phosphoric acid (H3PO4)

Temperature: 300°C

Pressure: 60 atm



Fermentation is the conversion of sugar, e.g. glucose into ethanol by enzymes from yeast.



Catalyst: Zymase (enzyme found in yeast)

Temperature: 30°C  –  The process is carried out at low temperatures as not to denature the enzymes.

Other: Anaerobic (no oxygen present) – if oxygen were present, the yeast produce carbon dioxide and water instead of ethanol.