Iron, Extraction, Uses, Rusting and Prevention for SS 3

Class: SS 3
Term: First Term
Week: 5
Age: 16 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Metals and Non-metals
Previous Lesson: Copper, Extraction, Properties and Uses
Topic: IRON
Subject Matter: Extraction; Uses; Rusting of iron and methods of prevention

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Identify the main ore of iron.
• State the raw materials used in the extraction of iron.
• Describe the process of iron extraction in the blast furnace.
• List at least three uses of iron and its alloys.
• Define rusting of iron.
• State the conditions necessary for rusting to occur.
• Explain various methods of preventing iron from rusting.

Affective Domain

• Appreciate the economic importance of iron and its alloys.
• Recognize the need for preventing corrosion of iron materials.
• Participate actively in discussions about iron and its properties.

Psychomotor Domain

• Draw a simple diagram of a blast furnace (optional).
• Set up an experiment to demonstrate the conditions for rusting.
• Suggest practical ways to prevent rusting in everyday items.

Social Domain

• Collaborate with peers in group activities and discussions.
• Share ideas and observations regarding iron and its properties.

Reference Materials

The following resources were used in planning this lesson:

• 2025 Revised 9 Years Basic Education Curriculum
• Relevant State Unified Scheme of Work
• Essential Chemistry for Senior Secondary Schools by Odesina, I.A.
• The HeadTeacher Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Diagram of a blast furnace
• Samples of iron ore (e.g., haematite)
• Samples of iron products (nails, keys, spoons)
• Rusted nails, keys, spoons, etc.
• Test tubes, beakers
• Water, anhydrous calcium chloride, boiled water, oil
• Paint, grease, zinc-coated iron (galvanized iron)
• Chart showing uses of iron

Rationale for the Lesson

This lesson provides students with a fundamental understanding of iron, a vital metal in modern society. It explains how iron is obtained from its ore, its diverse applications, and the chemical process of rusting. Understanding these concepts helps students appreciate the importance of chemistry in industry and everyday life, and equips them with knowledge to prevent material degradation.

Prerequisite/Previous Knowledge

Students should have a basic understanding of metals, non-metals, chemical reactions, and oxidation from their previous chemistry lessons.

Lesson Content/Board Summary

IRON

Extraction of Iron (Blast Furnace Process)

Iron is extracted from its ore, mainly haematite ((Fe_2O_3)), using a blast furnace. The raw materials used are:

1. Iron ore (Haematite, (Fe_2O_3)): Provides the iron.
2. Coke (Carbon): Acts as a reducing agent and fuel.
3. Limestone (Calcium carbonate, (CaCO_3)): Removes acidic impurities (slagging agent).

The process involves:

1. Heating: Raw materials are fed into the top of the blast furnace and heated by a blast of hot air from the bottom.
2. Formation of reducing agent: Coke burns in hot air to produce carbon monoxide, which is the main reducing agent.
   (C(s) + O_2(g) rightarrow CO_2(g))
   (CO_2(g) + C(s) rightarrow 2CO(g))
3. Reduction of iron ore: Carbon monoxide reduces the iron oxide to molten iron.
   (Fe_2O_3(s) + 3CO(g) rightarrow 2Fe(l) + 3CO_2(g))
4. Slag formation: Limestone decomposes to calcium oxide, which reacts with acidic impurities (silica, (SiO_2)) to form molten slag (calcium silicate).
   (CaCO_3(s) rightarrow CaO(s) + CO_2(g))
   (CaO(s) + SiO_2(s) rightarrow CaSiO_3(l))

Molten iron (pig iron) and molten slag are tapped off separately from the bottom of the furnace.

Uses of Iron and its Alloys

Iron is rarely used in its pure form due to its softness. It is usually alloyed with carbon and other metals to produce:

1. Cast Iron: Contains 2-4% carbon. It is hard, brittle, and used for making pipes, engine blocks, and machine parts.
2. Wrought Iron: Contains less than 0.2% carbon. It is tough, malleable, ductile, and used for making ornamental gates, chains, and agricultural implements.
3. Steel: An alloy of iron with carbon (0.2-1.5%) and other metals. It is strong, tough, and widely used in construction, car manufacturing, tools, and machinery.

Rusting of Iron

Rusting is the common term for the corrosion of iron and its alloys, such as steel. It is an electrochemical process that occurs when iron reacts with oxygen and water (moisture) to form hydrated iron (III) oxide, commonly known as rust.

Conditions for Rusting:

1. Oxygen (from air)
2. Water (moisture)

The presence of impurities, acids, and salts (like in saltwater) accelerates the rusting process.

Chemical Equation for Rusting:

(4Fe(s) + 3O_2(g) + 2xH_2O(l) rightarrow 2Fe_2O_3 cdot xH_2O(s)) (Hydrated Iron(III) Oxide – Rust)

Methods of Preventing Rusting

Rusting can be prevented by:

1. Painting: Applying a layer of paint prevents oxygen and water from reaching the iron surface.
2. Oiling/Greasing: Coating with oil or grease creates a barrier against air and moisture, commonly used for machine parts and tools.
3. Galvanizing: Coating iron with a layer of zinc. Zinc is more reactive than iron, so it corrodes preferentially (sacrificial protection) and also provides a physical barrier.
4. Tin Plating: Coating iron with a layer of tin. Tin provides a physical barrier, but if scratched, iron rusts faster as tin is less reactive. Used for food cans.
5. Electroplating: Coating iron with a thin layer of a less reactive metal like chromium or nickel using electrolysis. This provides a protective and decorative finish.
6. Sacrificial Protection: Attaching a more reactive metal (e.g., magnesium or zinc) to the iron. The more reactive metal corrodes instead of the iron. Used for underground pipes and ship hulls.
7. Alloying: Mixing iron with other metals to form rust-resistant alloys, such as stainless steel (iron, chromium, nickel).

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Guided Practice, Question and Answer, Explanation, Observation, Practical Activity.

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Activating prior knowledge

Teacher’s Activity: The teacher greets the students and asks them to name some common metals they know and their uses. The teacher then introduces iron as a very important metal and states the lesson topic.

Pupils’ Activity: Students respond to questions about common metals and listen to the introduction of the lesson.

Learning Point: Introduction to iron

Step 2: Extraction of Iron

Time: 10 minutes

Teaching Skill: Explanation/Illustration

Teacher’s Activity: The teacher explains the blast furnace process for extracting iron, discussing the raw materials (iron ore, coke, limestone) and their roles. The teacher may use a diagram of a blast furnace to illustrate the process and write down key reactions.

Pupils’ Activity: Students observe the diagram, listen to the explanation, and ask questions for clarification. They copy the key reactions.

Learning Point: Iron extraction process

Step 3: Uses of Iron

Time: 5 minutes

Teaching Skill: Discussion/Listing

Teacher’s Activity: The teacher discusses the various forms of iron (cast iron, wrought iron, steel) and their specific uses, highlighting how alloying improves iron’s properties. The teacher shows samples of iron products.

Pupils’ Activity: Students identify the different forms of iron and discuss their uses, observing the samples.

Learning Point: Uses of iron and alloys

Step 4: Rusting of Iron

Time: 8 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher defines rusting, explains the conditions necessary for it (oxygen and water), and shows rusted iron items. The teacher can set up a simple experiment (e.g., iron nails in different conditions: dry air, water, boiled water with oil) to be observed over time (for future lessons).

Pupils’ Activity: Students observe the rusted items, listen to the explanation, and discuss the conditions for rusting. They note down the chemical equation.

Learning Point: Conditions for rusting

Step 5: Prevention of Rusting

Time: 7 minutes

Teaching Skill: Explanation/Examples

Teacher’s Activity: The teacher explains various methods of preventing rusting, such as painting, oiling, galvanizing, tin plating, electroplating, and sacrificial protection. The teacher shows examples of items protected by these methods.

Pupils’ Activity: Students listen to the explanations, identify different prevention methods, and discuss their applications.

Learning Point: Methods of rust prevention

Step 6: Practical Application Discussion

Time: 3 minutes

Teaching Skill: Guided Discussion

Teacher’s Activity: The teacher leads a brief discussion on how students can apply the knowledge of rust prevention in their daily lives, e.g., caring for metal tools, bicycles, or gates.

Pupils’ Activity: Students share practical examples of rust prevention from their experiences.

Learning Point: Real-world rust prevention

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. Name the main ore of iron.
2. List two raw materials used in the blast furnace.
3. What are the two essential conditions for rusting?
4. State three methods of preventing iron from rusting.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Understanding iron concepts

Step 8: Note-Taking

Time: 4 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on iron extraction, uses, rusting, and prevention into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording lesson notes

Step 9: Conclusion

Time: 3 minutes

Teaching Skill: Summarization

Teacher’s Activity: The teacher briefly summarizes the key points of the lesson, emphasizing the importance of iron and the need to prevent its degradation through rusting. The teacher encourages students to observe iron products and their protection methods around them.

Pupils’ Activity: Students listen to the summary and reflect on the lesson’s main ideas.

Learning Point: Iron lesson consolidation

Continuous Assessment/Further Study

Type: Homework

Instruction: Answer the following questions in your notebook.

1. Describe the role of coke and limestone in the extraction of iron.
2. Differentiate between cast iron and steel based on their carbon content and uses.
3. Design a simple experiment to show that both air and water are necessary for rusting. Draw and label your setup.
4. Explain why galvanizing is considered a more effective method of rust prevention than tin plating, especially if the coating is scratched.

Lesson Keywords

• Iron – A metallic element, Fe, widely used in industry.
• Haematite – The main ore of iron, (Fe_2O_3).
• Blast Furnace – A large industrial furnace used for smelting iron ore.
• Pig Iron – Crude iron produced in a blast furnace, containing high carbon content.
• Slag – A glassy by-product formed during smelting, consisting of impurities.
• Rusting – The corrosion of iron, forming hydrated iron(III) oxide.
• Galvanizing – Coating iron with zinc to prevent rusting.
• Sacrificial Protection – Using a more reactive metal to protect iron from corrosion.

Differentiation

For struggling learners: Provide simplified diagrams of the blast furnace and a checklist of conditions for rusting. Focus on identifying key terms and basic prevention methods. Use visual aids and concrete examples.
For advanced learners: Encourage research into the specific chemical reactions within the blast furnace or the electrochemical mechanism of rusting. Ask them to compare different types of steel and their applications, or to investigate novel methods of corrosion prevention.

Suggested Lesson Videos

For further understanding, students can search for videos on YouTube using the terms:

• “Extraction of Iron in Blast Furnace”
• “What is Rusting and How to Prevent It”
• “Uses of Iron and Steel”

Teacher Guide for Using This Lesson Plan

Before the lesson, ensure you have prepared all instructional materials, including diagrams of the blast furnace, samples of iron ore, various iron products (new and rusted), and materials for demonstrating rust prevention. If possible, set up the simple rusting experiment (iron nails in different conditions) a few days in advance so students can observe the results in a follow-up lesson. During the lesson, explain the complex process of iron extraction clearly, breaking it down into manageable steps. Emphasize the practical relevance of understanding rusting and its prevention methods, linking them to everyday objects. Encourage students to actively participate in discussions and ask questions. Allow sufficient time for students to copy the Board Summary notes accurately in Step 8. For the evaluation, ensure questions cover all aspects of the lesson to check comprehension effectively.