Topic: Organic Chemistry – Alcohols
Lesson 1: Manufacture of Ethanol
| Section | Details |
|---|---|
| Objective | – Describe the manufacture of ethanol by fermentation and catalytic addition of steam to ethene.- Compare the advantages and disadvantages of both methods. |
| Activities | – Starter (5 mins): Show a bottle of ethanol and ask: “How do you think ethanol is made?”- Main (25 mins): 1. Explain fermentation: – Process: Aqueous glucose C6H12O6C_6H_{12}O_6 → Ethanol 2C2H5OH2C_2H_5OH + Carbon dioxide 2CO22CO_2. – Conditions: 25–35°C, yeast as a catalyst, anaerobic conditions (absence of oxygen). 2. Explain catalytic addition of steam to ethene: – Process: Ethene C2H4C_2H_4 + Water H2OH_2O → Ethanol C2H5OHC_2H_5OH. – Conditions: 300°C, 60 atm, acid catalyst (e.g., phosphoric acid). 3. Compare methods: – Fermentation: Renewable, low-tech, slower, impure ethanol. – Catalytic hydration: Faster, produces pure ethanol, requires non-renewable resources and high energy. – Plenary (10 mins): Students complete a table comparing the two methods of ethanol production. |
| Resources | Fermentation setup diagram, molecular models, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a short essay on the environmental impact of ethanol production using fermentation and catalytic hydration. |
| Assessment | Worksheet: Compare the two methods of ethanol production and identify key differences. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q6(a) – Manufacture of ethanol. |
Lesson 2: Combustion of Alcohols
| Section | Details |
|---|---|
| Objective | – Describe the combustion of alcohols.- Write balanced equations for the combustion of ethanol. |
| Activities | – Starter (5 mins): Burn a small sample of ethanol and ask: “What are the products of this reaction?”- Main (25 mins): 1. Explain combustion as a reaction with oxygen, producing carbon dioxide and water. – Complete combustion of ethanol: C2H5OH+3O2→2CO2+3H2OC_2H_5OH + 3O_2 → 2CO_2 + 3H_2O. – Incomplete combustion produces carbon monoxide or soot: C2H5OH+O2→CO+H2OC_2H_5OH + O_2 → CO + H_2O. 2. Discuss the energy released during combustion and its relevance as a fuel. 3. Students practice writing balanced equations for the combustion of alcohols.- Plenary (10 mins): Students complete a worksheet predicting products of combustion reactions for different alcohols. |
| Resources | Ethanol, Bunsen burner, reaction equations, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Research the use of ethanol as a biofuel and its advantages over fossil fuels. |
| Assessment | Worksheet: Write balanced equations for the combustion of ethanol and other alcohols. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/19 Q6(b) – Combustion of alcohols. |
Lesson 3: Uses of Ethanol
| Section | Details |
|---|---|
| Objective | – State the uses of ethanol as a solvent and fuel.- Discuss why ethanol is suitable for these uses. |
| Activities | – Starter (5 mins): Show everyday products containing ethanol (e.g., hand sanitizer, alcohol-based fuel) and ask: “What makes ethanol useful in these products?”- Main (25 mins): 1. Discuss ethanol as a solvent: – Dissolves a wide range of substances. – Used in perfumes, paints, and hand sanitizers. 2. Explain ethanol as a fuel: – High energy release during combustion. – Used in biofuels and blended with petrol. 3. Discuss advantages and disadvantages of ethanol as a fuel: – Renewable, cleaner burning. – May compete with food crops for land.- Plenary (10 mins): Students create a table summarizing the uses of ethanol and their reasons. |
| Resources | Ethanol-based products, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a paragraph explaining why ethanol is used in hand sanitizers and biofuels. |
| Assessment | Worksheet: Identify and explain the uses of ethanol in different applications. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/20 Q6(c) – Uses of ethanol. |
Key Notes for Students:
- Manufacture of Ethanol:
- Fermentation: Renewable, requires glucose and yeast, produces impure ethanol.
- Catalytic hydration of ethene: Non-renewable, produces pure ethanol, high energy demand.
- Combustion of Alcohols:
- Ethanol burns in oxygen to produce CO2CO_2 and H2OH_2O.
- Complete combustion: C2H5OH+3O2→2CO2+3H2OC_2H_5OH + 3O_2 → 2CO_2 + 3H_2O.
- Incomplete combustion produces COCO or carbon (soot).
- Uses of Ethanol:
- As a solvent: Dissolves substances in perfumes, paints, and sanitizers.
- As a fuel: Clean-burning and renewable energy source.
Notes for Teachers:
- Use practical demonstrations (e.g., combustion of ethanol) to engage students.
- Encourage comparisons of ethanol production methods to highlight real-world applications and sustainability.
- Discuss the relevance of ethanol in daily life and its role in the global energy sector.
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