Alcohol Uses (GCSE Chemistry)

Alcohol Uses

Uses of Alcohols

• Alcohols can be used as fuels. The first four alcohols can be used as fuels. For example, they are commonly used in internal combustion  engines.
• Alcohols can be used as solvents. Alcohols are unique as they can dissolve many substances that are insoluble in water. They are commonly used in perfumes and deodorants.

Forming Ethanol

• Alcohol can be produced from sugar solutions. Through the process of fermentation, alcohols can be formed from sugar solutions.
• Yeast is used in fermentation. During the process of fermentation, an enzyme in yeast is used under anaerobic conditions.
• Alcohol can also be produced using steam. By reacting ethene with steam, ethanol is formed. This is usually with the addition of a phosphoric acid catalyst.

Fermentation Conditions

• Optimum reaction conditions lead to a high yield. By using the optimum conditions for fermentation, a high yield of ethanol can be produced. This makes production more efficient.
• Fermentation has specific optimum conditions. If the temperature of fermentation is above 40°C, then the yeast enzyme could become denatured. The temperature of the reaction should be between 30⁰C and 35⁰C, and the environment should be anaerobic. The following reaction shows the production of ethanol:

Sugar + yeast ⟶ ethanol + carbon dioxide

• How does fermentation work? The yeast anaerobically respires using the sugar solution. This forms ethanol and carbon dioxide.
• What are the advantages of producing ethanol by fermentation? The reaction takes place at about 30°C and atmospheric pressure. This requires very little energy and is therefore cheap. As plants are used to provide the glucose, the process is carbon neutral.
• What are the disadvantages of producing ethanol by fermentation? It is a batch process, which makes it labour intensive. The reaction is  very slow and takes a few weeks. The purity of the alcohol produced is about 15%, and it needs to be distilled to increase the concentration. Distillation requires energy.

Reacting with Steam Conditions

• Ethene is reacted with steam. When an alkene, such as ethene, reacts with water an alcohol, such as ethanol, is formed.
• Certain conditions are required. A temperature of around 300 degrees and a pressure of about 60-70 atm is needed. Also a phosphoric acid catalyst is usually used.
• What are the advantages of producing ethanol using steam? Compared to fermentation, a much higher temperature and pressure is required. This requires more energy and is therefore much more expensive. It also uses non-renewable raw materials.
• What are the disadvantages of producing ethanol using steam? Compared to fermentation, this process is much faster and can run continuously. It is less labour intensive and less workers are needed for the process.