Study Notes
Alcohols are organic compounds that contain the hydroxyl (-OH) functional group, which is responsible for their characteristic reactions. They are a homologous series with the general formula CnH2n+1OH. Ethanol can be manufactured by fermentation of glucose or by catalytic addition of steam to ethene. It is used as a solvent and a fuel and undergoes complete combustion to produce carbon dioxide and water.
- Fermentation — a process of producing ethanol by converting glucose in the absence of oxygen using yeast enzymes. Example: Glucose → ethanol + carbon dioxide
- Catalytic Addition of Steam — a method of producing ethanol by reacting ethene with steam using a phosphoric acid catalyst. Example: Ethene + steam → ethanol
- Complete Combustion — a reaction where ethanol burns in oxygen to produce carbon dioxide and water, releasing heat energy. Example: CH3CH2OH + 3O2 → 2CO2 + 3H2O
Exam Tips
Key Definitions to Remember
- Hydroxyl group: -OH functional group in alcohols
- Fermentation: Process of converting glucose to ethanol and carbon dioxide using yeast
- Catalytic addition of steam: Reaction of ethene with steam to produce ethanol
Common Confusions
- Confusing fermentation with hydration
- Misunderstanding the conditions required for fermentation and catalytic addition of steam
Typical Exam Questions
- What is the general formula for alcohols? CnH2n+1OH
- How is ethanol produced by fermentation? By converting glucose in the absence of oxygen using yeast
- What are the products of the complete combustion of ethanol? Carbon dioxide and water
What Examiners Usually Test
- Understanding of the conditions for fermentation and catalytic addition of steam
- Ability to write balanced equations for the production and combustion of ethanol
- Knowledge of the uses of ethanol as a solvent and a fuel