How do you produce ethanol by fermentation?

Ethanol is produced by fermentation through the action of yeast on glucose, under anaerobic conditions.

Fermentation is a biological process where sugar is converted into alcohol and carbon dioxide by yeast or bacteria. In the production of ethanol, the sugar used is typically glucose, which is derived from various sources such as corn, sugarcane, or even cellulose. The yeast used is usually a species of Saccharomyces.

The process begins with the yeast breaking down the glucose in an anaerobic environment, meaning there is no oxygen present. This is because yeast, under anaerobic conditions, will convert glucose into ethanol and carbon dioxide. This is different from aerobic respiration, where yeast would break down glucose into water and carbon dioxide, but no ethanol.

The chemical equation for this process is: C6H12O6 (glucose) → 2C2H5OH (ethanol) + 2CO2 (carbon dioxide). This reaction is exothermic, meaning it releases heat.

The ethanol produced through fermentation is then distilled to increase its concentration. This is because the fermentation process only produces a solution with around 10-15% ethanol due to the yeast dying off beyond this concentration due to the toxicity of ethanol.

It's important to note that the fermentation process is not 100% efficient. Not all the glucose is converted into ethanol and carbon dioxide. Some of it is used by the yeast for growth and reproduction, and some may be converted into other by-products.

In summary, the production of ethanol by fermentation involves the breakdown of glucose by yeast in an anaerobic environment, resulting in the formation of ethanol and carbon dioxide. This process is widely used in the production of alcoholic beverages and biofuels.