Topic: Metals – Extraction of Metals
Lesson 1: Ease of Metal Extraction and Reactivity Series
| Section | Details |
|---|---|
| Objective | Describe the ease of obtaining metals from their ores in relation to their position in the reactivity series. |
| Activities | – Starter (5 mins): Show a chart of the reactivity series and ask: “Why are some metals easier to extract than others?”- Main (25 mins): 1. Explain how metals high in the reactivity series (e.g., potassium, sodium) require electrolysis due to their strong bonds with oxygen. 2. Metals lower in the series (e.g., iron, zinc) can be extracted using carbon reduction. 3. Unreactive metals like gold occur naturally in their elemental form and do not require extraction from ores.- Plenary (10 mins): Students arrange metals in the reactivity series based on their extraction methods. |
| Resources | Reactivity series chart, worksheets, videos on metal extraction. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a short explanation of why gold can be found naturally while iron cannot. |
| Assessment | Worksheet: Match metals to their extraction methods based on their position in the reactivity series. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q5(a) – Reactivity series and metal extraction methods. |
Lesson 2: Extraction of Iron in the Blast Furnace
| Section | Details |
|---|---|
| Objective | Describe the extraction of iron from hematite in the blast furnace, including the chemical reactions involved. |
| Activities | – Starter (5 mins): Show a diagram of the blast furnace and ask: “What do you think happens at each level of the furnace?”- Main (25 mins): 1. Explain the raw materials used: hematite (iron ore), coke (carbon), limestone (calcium carbonate), and hot air. 2. Describe key reactions: – Burning of coke: C+O2→CO2\text{C} + \text{O}_2 → \text{CO}_2. – Reduction of carbon dioxide to carbon monoxide: CO2+C→2CO\text{CO}_2 + \text{C} → 2\text{CO}. – Reduction of iron(III) oxide: Fe2O3+3CO→2Fe+3CO2\text{Fe}_2\text{O}_3 + 3\text{CO} → 2\text{Fe} + 3\text{CO}_2. – Thermal decomposition of limestone: CaCO3→CaO+CO2\text{CaCO}_3 → \text{CaO} + \text{CO}_2. – Formation of slag: CaO+SiO2→CaSiO3\text{CaO} + \text{SiO}_2 → \text{CaSiO}_3. 3. Relate each step to its purpose in the process.- Plenary (10 mins): Students complete a labeled diagram of the blast furnace showing key reactions. |
| Resources | Diagrams of the blast furnace, worksheets, reaction equations. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write a summary of the chemical reactions occurring in the blast furnace, including their purposes. |
| Assessment | Worksheet: Label a diagram of the blast furnace and explain the function of each reaction. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q6(a) – Extraction of iron in the blast furnace. |
Lesson 3: Extraction of Aluminium from Bauxite
| Section | Details |
|---|---|
| Objective | Describe the extraction of aluminium from purified bauxite/aluminium oxide, including the role of cryolite, the need to replace carbon anodes, and the reactions at the electrodes. |
| Activities | – Starter (5 mins): Show a diagram of the electrolysis cell for aluminium extraction and ask: “What do you think happens at the electrodes?”- Main (25 mins): 1. Explain the process: – Purified bauxite (aluminium oxide) is dissolved in molten cryolite to lower its melting point. – Electrolysis is used to extract aluminium. 2. Discuss the reactions at the electrodes: – At the cathode: Al3++3e−→Al\text{Al}^{3+} + 3\text{e}^- → \text{Al}. – At the anode: 2O2−→O2+4e−2\text{O}^{2-} → \text{O}_2 + 4\text{e}^-. 3. Explain why carbon anodes need to be replaced regularly (react with oxygen to form CO2\text{CO}_2).- Plenary (10 mins): Students complete a flowchart summarizing the steps in aluminium extraction. |
| Resources | Diagrams of electrolysis cells, worksheets, reaction equations. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write an explanation of the role of cryolite in aluminium extraction and why it is important. |
| Assessment | Worksheet: Describe the reactions at the cathode and anode during aluminium extraction. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/19 Q6(b) – Electrolysis in aluminium extraction. |
Key Notes for Students:
- Metal Extraction and Reactivity:
- Metals high in the reactivity series are extracted by electrolysis.
- Metals lower in the series are extracted by carbon reduction.
- Unreactive metals (e.g., gold) occur naturally.
- Blast Furnace Reactions:
- Coke burns to produce heat and carbon monoxide.
- Carbon monoxide reduces iron(III) oxide to iron.
- Limestone decomposes to form calcium oxide, which reacts with silica to form slag.
- Electrolysis of Aluminium:
- Aluminium oxide is dissolved in cryolite to reduce energy costs.
- Aluminium is reduced at the cathode, and oxygen is oxidized at the anode.
- Carbon anodes react with oxygen, requiring regular replacement.
Notes for Teachers:
- Use visual aids (e.g., diagrams, videos) to explain complex processes like the blast furnace and electrolysis.
- Highlight the environmental and economic implications of metal extraction.
- Provide ample practice with reaction equations to reinforce understanding.
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