Equilibria · SHS3 Chemistry

Lesson notes

Learning Objectives

Indicator: 3.1.2.LI.5 - Explain the concept of corrosion of metals and its application in everyday life.

By the end of the lesson, learners can:

Define corrosion and rusting and distinguish clearly between the two terms using everyday examples from their surroundings.
Write and explain the half-equations and overall equation for the electrochemical process involved in the rusting of iron.
Investigate experimentally the conditions necessary for rusting and the factors that affect the rate of rusting.
Evaluate at least four methods of preventing rusting and classify each as a redox or non-redox method.
Assess the economic and social impact of corrosion in Ghana and justify appropriate prevention strategies for different situations.

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Curriculum details

Strand: Physical Chemistry (Strand 1)
Sub-strand: Equilibria (1.2)
Content standard: 3.1.2.CS.4 - Demonstrate knowledge and understanding of redox and apply its principles to electrochemical cells as well as their importance in everyday life. 3.1.2.LO.1 Use the knowledge in pH to distinguish between solutions that are acidic, neutral or basic. 5 Gender Equality and Social Inclusion 6 Socio-Emotional Learning 3.1.2.LO.2 Use your knowledge and understanding of concepts in hydration and hydrolysis to determine the types of salts. 3.1.2.LO.3 Use the understanding of hydrolysis of salts to decide on suitable indicator as well as plot and interpret titration curves. 3.1.2.LO.4 Describe oxidation and reduction reactions and apply their principles to electrochemical cells as well as their importance in everyday life.
Indicator: 3.1.2.LI.5 - Explain the concept of corrosion of metals and its application in everyday life.
Suggested placement: Semester 1, Week 17 (Week 17 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 103

Exemplars (from the NaCCA curriculum)

Initiating Talk for Learning:
- Using think-pair-share approach, explain the following terms: a. Corrosion b. Rusting
- Use equations to explain electrochemical processes involved in rusting.
Experiential Learning:
- In mixed ability or mixed gender groups where applicable, conduct an experiment to investigate the conditions needed for rusting and conditions that also affect the rate of rusting.
- Design experiments to investigate ways of preventing rusting.
Talk for Learning:
- Reflect on the results of the investigation and explain redox and non-redox methods of preventing rusting
- Discuss the impact of rusting and corrosion in everyday life.
- Watch a video of the lesson to reinforce the concept.
Teaching and Learning Materials:
- * Test tubes in a rack * Strips of copper foil * Strips of zinc foil * * 0.1M potassium bromide
- Strip of silver wire * * ICT tools Emery paper * * Calculator 0.5 M copper sulphate solution * 0.5 M zinc sulphate solution
- * 0.1 M silver nitrate solution * 50 ml Burettes * 25 ml pipettes * 250 ml conical flasks * 100 ml beakers * White tiles
- * Retort stands * solution
- KMnO 4 * * 0.02M potassium Iron (II) solution * manganate (VII) Iodine solution * Potassium iodide * Na S O 2 2 3 * Starch * * Electrolysis cell Test tubes * Test tube rack
- * Copper powder * Zinc powder * * Clamps and stands Bromine water * * Cover slides 0.1 M potassium iodide solution * 0.1 M potassium chloride solution
- * 0.1 M Iron (III) chloride
- * Power pack
- * Connecting wires and clips
- * Wooden splint * Droppers * 1 M tetraoxosulphate (VI) acid * 1 M sodium chloride solution
- * 1 M copper(II) chloride * Identical fresh nails * Test tube in test tube racks * Stoppers * Spatula * PH sensor * Temperature sensor * Stands and clamps
- * Calcium chloride * Oil * Iron coated with zinc * Iron coated with tin * Iron filings * Salt
Assessment (3.1.2.AS.5). The document marks these depth-of-knowledge levels for this indicator: Level 4 Extended critical thinking and reasoning.