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)
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.