Topic: Chemical Reactions – Redox
Lesson 1: Oxidation Numbers and Roman Numerals
| Section | Details |
|---|---|
| Objective | Use Roman numerals to indicate the oxidation number of an element in a compound. |
| Activities | – Starter (5 mins): Show examples of compounds with Roman numerals (e.g., iron(III) oxide, manganese(VII) oxide) and ask, “What do the Roman numerals indicate?”- Main (25 mins): 1. Define oxidation number. 2. Teach rules for determining oxidation numbers in compounds. 3. Practice assigning oxidation numbers using examples.- Plenary (10 mins): Students complete a worksheet matching compounds to their oxidation numbers. |
| Resources | Examples of compounds, worksheets, periodic table. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write oxidation numbers for elements in provided compounds. |
| Assessment | Worksheet: Assign oxidation numbers to elements in given compounds. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q3(a) – Assigning oxidation numbers using Roman numerals. |
Lesson 2: Definition of Redox Reactions
| Section | Details |
|---|---|
| Objective | Define redox reactions as involving simultaneous reduction and oxidation. Define oxidation and reduction in terms of oxygen, electrons, and oxidation number. |
| Activities | – Starter (5 mins): Show an example reaction (e.g., 2Mg + O₂ → 2MgO) and ask: “What changes are happening to magnesium and oxygen?”- Main (25 mins): 1. Define redox reactions. 2. Explain oxidation (gain of oxygen, loss of electrons, increase in oxidation number). 3. Explain reduction (loss of oxygen, gain of electrons, decrease in oxidation number). 4. Provide practice identifying oxidation and reduction in reactions.- Plenary (10 mins): Students summarize oxidation and reduction in a table. |
| Resources | Reaction examples, worksheets, diagrams. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write definitions of oxidation and reduction with examples for each method. |
| Assessment | Worksheet: Identify oxidation and reduction in reactions based on oxygen, electrons, and oxidation number. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q3(b) – Identifying oxidation and reduction in reactions. |
Lesson 3: Identifying Redox Reactions
| Section | Details |
|---|---|
| Objective | Identify redox reactions based on: (a) gain and loss of oxygen, (b) gain and loss of electrons, (c) changes in oxidation number. |
| Activities | – Starter (5 mins): Pose the question: “How can we determine if a reaction is redox?”- Main (25 mins): 1. Demonstrate identifying redox reactions using oxygen gain/loss and electron transfer. 2. Explain rules for identifying redox reactions by changes in oxidation number (e.g., sum of oxidation numbers in a compound is zero). 3. Provide examples for practice.- Plenary (10 mins): Students classify reactions as redox or non-redox, justifying their answers. |
| Resources | Worksheets, periodic table, reaction examples. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Practice identifying redox reactions in given equations using oxidation number changes. |
| Assessment | Worksheet: Identify redox reactions based on oxygen, electrons, and oxidation number. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q3(c) – Identifying redox reactions using oxidation numbers. |
Lesson 4: Colour Changes in Redox Reactions
| Section | Details |
|---|---|
| Objective | Identify redox reactions using the colour changes of acidified aqueous potassium manganate(VII) and aqueous potassium iodide. |
| Activities | – Starter (5 mins): Show before-and-after pictures of redox reactions involving KMnO₄ and KI and ask: “What is causing the colour change?”- Main (25 mins): 1. Explain the colour changes of KMnO₄ (purple to colourless) and KI (colourless to brown). 2. Discuss how these colour changes indicate oxidation and reduction. 3. Conduct simple experiments using KMnO₄ and KI.- Plenary (10 mins): Students summarize the colour changes for each substance. |
| Resources | Acidified KMnO₄, KI solutions, beakers, reaction examples, worksheets. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a summary of the colour changes and their significance in redox reactions. |
| Assessment | Worksheet: Predict the colour changes in given redox reactions. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q4(b) – Colour changes in redox reactions. |
Lesson 5: Oxidising and Reducing Agents
| Section | Details |
|---|---|
| Objective | Define oxidising agents and reducing agents. Identify oxidation, reduction, oxidising agents, and reducing agents in redox reactions. |
| Activities | – Starter (5 mins): Ask: “What substances cause oxidation or reduction in reactions?”- Main (25 mins): 1. Define oxidising agents (cause oxidation, are reduced) and reducing agents (cause reduction, are oxidised). 2. Provide examples and practice identifying agents in reactions. 3. Relate oxidising/reducing agents to industrial and laboratory applications.- Plenary (10 mins): Students complete a table classifying substances as oxidising or reducing agents in given reactions. |
| Resources | Reaction examples, worksheets, periodic table. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a paragraph explaining the role of oxidising and reducing agents in a reaction of your choice. |
| Assessment | Worksheet: Identify oxidising and reducing agents in redox reactions. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/19 Q4(a) – Identifying oxidising and reducing agents. |
Notes for Teachers:
- Use hands-on experiments to make abstract redox concepts tangible for students.
- Reinforce connections between oxidation numbers, electron transfer, and chemical changes.
- Encourage students to explain concepts in their own words to solidify understanding.
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