Final answer:
Ethanol can be synthesized through the fermentation of sugars by yeast or chemically by adding water to ethylene using an acid as a catalyst. Both methods produce ethanol for use as a biofuel, in beverages, and for industrial purposes.
Step-by-step explanation:
Two main methods for synthesizing ethanol involve different processes. One common method is the fermentation of sugars. In this biological process, sugars are converted into ethanol by the action of yeast, especially in the brewing and distilling industries. Glucose fermentation to ethanol can be represented as Figure 9.5.3 in textbooks. The other method is a chemical synthesis process, where large quantities of ethanol are produced industrially by the addition of water to ethylene in a reaction catalyzed by an acid. This process typically occurs at a high temperature and involves the use of catalytic substances to accelerate the chemical reaction.
Both methods are widely used for producing ethanol, which is used as a chief biofuel, a recreational drug in alcoholic beverages, and for various industrial applications. Ethanol is mixed with conventional gasoline to enhance combustion efficiency and reduce pollutant emissions.