Question

Write chemical equation and the method of preparation of ethanol from molasses.

Hint:

In fermentation, temperature must be maintained around 30–35$^\circ$C; at higher temperature yeast dies and at lower temperature fermentation becomes slow.

Answer 1

Step 1: Raw material.
Molasses, a by-product of sugar industry, contains about 30–40% sucrose.

Step 2: Fermentation process.
Molasses is diluted with water and yeast (Saccharomyces cerevisiae) is added.
The enzyme invertase converts sucrose into glucose and fructose.
Then the enzyme zymase converts glucose/fructose into ethanol and carbon dioxide.
\[ C_{12}H_{22}O_{11} + H_2O \xrightarrow{\text{invertase}} C_6H_{12}O_6 \;+\; C_6H_{12}O_6 \]
\[ C_6H_{12}O_6 \xrightarrow{\text{zymase}} 2C_2H_5OH \;+\; 2CO_2 \]

Step 3: Distillation.
The fermented solution is distilled to obtain ethanol of higher purity.
\[ \boxed{\text{Thus, ethanol is prepared from molasses by fermentation followed by distillation.}} \]