Topic: Acids, Bases, and Salts – Characteristic Properties of Acids and Bases
Lesson 1: Acids and Bases – Fundamental Definitions
| Section | Details |
|---|---|
| Objective | – State that aqueous solutions of acids contain H+\text{H}^+ ions and alkalis contain OH−\text{OH}^- ions.- Define acids as proton donors and bases as proton acceptors.- State that bases are oxides or hydroxides of metals and alkalis are soluble bases. |
| Activities | – Starter (5 mins): Show examples of common acids (e.g., HCl) and alkalis (e.g., NaOH) and ask: “What makes them acidic or basic?”- Main (25 mins): 1. Define acids and alkalis in terms of H+\text{H}^+ and OH−\text{OH}^- ions. 2. Explain proton donors and acceptors with examples. 3. Differentiate bases and alkalis (e.g., NaOH as an alkali, CuO as a base).- Plenary (10 mins): Students complete a worksheet matching definitions to examples. |
| Resources | Examples of acids and bases, periodic table, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write definitions of acids, bases, and alkalis with two examples each. |
| Assessment | Worksheet: Classify compounds as acids, bases, or alkalis. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q2(a) – Definitions and examples of acids and bases. |
Lesson 2: Characteristic Reactions of Acids and Bases
| Section | Details |
|---|---|
| Objective | Describe the characteristic properties of acids and bases in terms of their reactions with metals, bases, carbonates, and ammonium salts. |
| Activities | – Starter (5 mins): Ask: “What happens when you mix acids and metals?”- Main (25 mins): 1. Demonstrate reactions of acids with metals (e.g., HCl + Mg → H₂ + MgCl₂). 2. Explain reactions of acids with bases and carbonates. 3. Discuss the reaction of bases with acids and ammonium salts. 4. Conduct a simple neutralisation experiment (e.g., NaOH + HCl → NaCl + H₂O).- Plenary (10 mins): Students summarize reaction types in a table with equations. |
| Resources | Metal strips, acids, bases, ammonium salts, reaction setups, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write balanced equations for the reactions demonstrated in class. |
| Assessment | Worksheet: Predict products of reactions between acids, bases, and carbonates. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q2(b) – Reactions of acids and bases. |
Lesson 3: Neutralisation and Indicators
| Section | Details |
|---|---|
| Objective | – State that neutralisation occurs between an acid and a base.- Describe the neutralisation reaction H+(aq)+OH−(aq)→H2O(ℓ)\text{H}^+ (\text{aq}) + \text{OH}^- (\text{aq}) → \text{H}_2\text{O} (\ell).- Describe the effects of acids and alkalis on litmus, thymolphthalein, and methyl orange. |
| Activities | – Starter (5 mins): Show a colour change with universal indicator in a neutralisation reaction and ask: “Why does the colour change?”- Main (25 mins): 1. Explain neutralisation and write the equation H++OH−→H2O\text{H}^+ + \text{OH}^- → \text{H}_2\text{O}. 2. Test acids and alkalis with litmus, thymolphthalein, and methyl orange. 3. Discuss colour changes and their pH ranges.- Plenary (10 mins): Students complete a table summarising indicator colours in acidic, neutral, and basic solutions. |
| Resources | Indicators, acids, alkalis, reaction setups, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Create a chart showing the pH range of litmus, thymolphthalein, and methyl orange. |
| Assessment | Worksheet: Predict indicator colours for given solutions. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/19 Q3(a) – Neutralisation and indicator colours. |
Lesson 4: Strong and Weak Acids
| Section | Details |
|---|---|
| Objective | – Define strong acids as completely dissociated in aqueous solution and weak acids as partially dissociated.- Provide examples of strong acids (e.g., HCl, H₂SO₄) and weak acids (e.g., CH₃COOH). Write symbol equations for their dissociation. |
| Activities | – Starter (5 mins): Ask: “Why do some acids react faster than others?”- Main (25 mins): 1. Define strong and weak acids. 2. Show dissociation equations (e.g., HCl→H++Cl−\text{HCl} → \text{H}^+ + \text{Cl}^-, CH3COOH⇌H++CH3COO−\text{CH}_3\text{COOH} ⇌ \text{H}^+ + \text{CH}_3\text{COO}^-). 3. Discuss conductivity of strong and weak acids and test with a conductivity meter.- Plenary (10 mins): Students compare strong and weak acids in a table. |
| Resources | Strong and weak acids, conductivity meter, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write the dissociation equations for nitric acid and ethanoic acid. |
| Assessment | Worksheet: Classify acids as strong or weak and write dissociation equations. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/20 Q3(c) – Strong and weak acids with dissociation equations. |
Lesson 5: Comparing pH and Hydrogen Ion Concentration
| Section | Details |
|---|---|
| Objective | Compare hydrogen ion concentration, neutrality, relative acidity, and alkalinity using universal indicator paper and pH scale. |
| Activities | – Starter (5 mins): Ask: “How can we compare the strength of acids and alkalis?”- Main (25 mins): 1. Explain how H+\text{H}^+ concentration relates to pH. 2. Demonstrate testing various solutions with universal indicator paper. 3. Discuss pH values for acids, bases, and neutral solutions.- Plenary (10 mins): Students arrange solutions in order of increasing acidity/alkalinity based on pH values. |
| Resources | Universal indicator paper, pH scale chart, solutions of varying pH, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Test three household substances with pH paper and record their pH values. |
| Assessment | Worksheet: Identify solutions as acidic, neutral, or basic based on pH values. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/21 Q3(d) – Comparing pH and acidity/alkalinity. |
Notes for Teachers:
- Use experiments to engage students and solidify their understanding of concepts like neutralisation and pH.
- Reinforce the link between theory (e.g., dissociation) and practical observations (e.g., indicator colours, conductivity).
- Highlight the real-world applications of acids and alkalis, such as cleaning products and industrial processes.
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