Topic: Organic Chemistry – Carboxylic Acids
Lesson 1: Reactions of Carboxylic Acids
| Section | Details |
|---|---|
| Objective | – Describe the reactions of carboxylic acids with metals, bases, and carbonates.- Write the names and formulae of the salts produced. |
| Activities | – Starter (5 mins): Show samples of common acids (e.g., vinegar) and ask: “How do acids react with metals and bases?”- Main (25 mins): 1. Discuss the general reactions of carboxylic acids: – With metals: Produces salt and hydrogen gas. 2CH3COOH+Mg→(CH3COO)2Mg+H22CH_3COOH + Mg → (CH_3COO)_2Mg + H_2. – With bases: Produces salt and water. CH3COOH+NaOH→CH3COONa+H2OCH_3COOH + NaOH → CH_3COONa + H_2O. – With carbonates: Produces salt, water, and carbon dioxide. 2CH3COOH+Na2CO3→2CH3COONa+H2O+CO22CH_3COOH + Na_2CO_3 → 2CH_3COONa + H_2O + CO_2. 2. Demonstrate the reaction of ethanoic acid with a metal (magnesium ribbon) and observe hydrogen gas evolution. 3. Students practice writing balanced equations for reactions with carboxylic acids.- Plenary (10 mins): Students complete a worksheet matching reactions to their products. |
| Resources | Samples of acids, metals, bases, carbonates, reaction equations, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write balanced equations for the reactions of ethanoic acid with sodium, sodium hydroxide, and sodium carbonate. |
| Assessment | Worksheet: Predict products and write equations for carboxylic acid reactions. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/19 Q6(b) – Reactions of carboxylic acids. |
Lesson 2: Formation of Ethanoic Acid
| Section | Details |
|---|---|
| Objective | – Describe the formation of ethanoic acid by the oxidation of ethanol using potassium manganate(VII) and bacterial oxidation during vinegar production. |
| Activities | – Starter (5 mins): Show a bottle of vinegar and ask: “How is vinegar made?”- Main (25 mins): 1. Explain oxidation of ethanol to ethanoic acid: – With potassium manganate(VII): C2H5OH+[O]→CH3COOH+H2OC_2H_5OH + [O] → CH_3COOH + H_2O (acidified aqueous KMnO4KMnO_4). – Observe the purple solution of KMnO4KMnO_4 turning colorless during oxidation. 2. Discuss bacterial oxidation during vinegar production: – Ethanol is oxidized by bacteria in the presence of air. C2H5OH+O2→CH3COOH+H2OC_2H_5OH + O_2 → CH_3COOH + H_2O. 3. Show a video or diagram of vinegar production.- Plenary (10 mins): Students complete a flow diagram showing the steps of ethanol oxidation to ethanoic acid. |
| Resources | Vinegar, potassium manganate(VII), worksheets, video on vinegar production. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write an explanation of how ethanoic acid is formed during vinegar production. |
| Assessment | Worksheet: Write equations and describe the steps for ethanol oxidation to ethanoic acid. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/20 Q6(c) – Formation of ethanoic acid. |
Lesson 3: Ester Formation
| Section | Details |
|---|---|
| Objective | – Describe the reaction of a carboxylic acid with an alcohol using an acid catalyst to form an ester.- Write and draw structural and displayed formulae of esters. |
| Activities | – Starter (5 mins): Show a sample of an artificial fragrance (ester) and ask: “How do you think this compound is made?”- Main (25 mins): 1. Introduce esterification reaction: – Carboxylic acid + Alcohol → Ester + Water. – Example: Ethanoic acid + Ethanol → Ethyl ethanoate + Water. CH3COOH+C2H5OH→CH3COOC2H5+H2OCH_3COOH + C_2H_5OH → CH_3COOC_2H_5 + H_2O. – Catalyst: Concentrated sulfuric acid. 2. Discuss the uses of esters (perfumes, flavorings, solvents). 3. Demonstrate the formation of an ester in a test tube (teacher-led demonstration). 4. Students practice drawing structural and displayed formulae for esters.- Plenary (10 mins): Students complete a worksheet naming esters and drawing their structures. |
| Resources | Ethanoic acid, ethanol, sulfuric acid, molecular models, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Draw and name the ester formed when methanol reacts with propanoic acid. |
| Assessment | Worksheet: Write equations, name esters, and draw their structural formulae. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q6(d) – Formation of esters. |
Key Notes for Students:
- Reactions of Carboxylic Acids:
- With metals: Produces salt and hydrogen (e.g., CH3COONaCH_3COONa).
- With bases: Produces salt and water (e.g., CH3COONa+H2OCH_3COONa + H_2O).
- With carbonates: Produces salt, water, and CO2CO_2 (e.g., CH3COONa+CO2+H2OCH_3COONa + CO_2 + H_2O).
- Formation of Ethanoic Acid:
- Chemical oxidation: Ethanol + Potassium manganate(VII) → Ethanoic acid.
- Bacterial oxidation: Ethanol + Oxygen → Ethanoic acid (vinegar production).
- Esterification:
- Carboxylic acid + Alcohol → Ester + Water.
- Example: CH3COOH+C2H5OH→CH3COOC2H5+H2OCH_3COOH + C_2H_5OH → CH_3COOC_2H_5 + H_2O.
Notes for Teachers:
- Use hands-on demonstrations to engage students in ester formation and acid reactions.
- Relate the chemistry of carboxylic acids to real-life examples like vinegar and fragrances.
- Provide opportunities to practice naming esters and writing reaction equations.
Leave a Reply