Corrosion and prevention — KCSE Chemistry

KCSE Chemistry · 65 practice questions · 4 syllabus objectives

17 easy23 medium25 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Describe the conditions necessary for rusting (oxygen and water) and write the equation for rust formation

Explain methods of preventing corrosion: painting, galvanising, electroplating, sacrificial protection and alloying

Explain the electrochemical nature of corrosion and relate it to the reactivity series

Corrosion and prevention

Sample Questions

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1
easySHORT ANSWER4 marks

Name two factors that affect the rate of corrosion in metals and explain how they influence the process. (4 marks)

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Part (a) — 2 marks
Presence of moisture/water (1 mk)
Presence of oxygen/air (1 mk)
Part (b) — 2 marks
Moisture provides a medium for electrochemical reactions to occur (1 mk)
Oxygen is necessary for the oxidation of metals, leading to corrosion (1 mk)
2
easySHORT ANSWER3 marks

Name three methods of preventing corrosion in metals. (3 marks)

View Marking Scheme
Part (a) — 3 marks
Painting (1 mk)
Galvanising (1 mk)
Electroplating (1 mk)
3
easySHORT ANSWER2 marks

State two advantages of using galvanisation to prevent corrosion of steel structures. (2 marks)

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Part (a) — 2 marks
Galvanisation provides a protective zinc coating that prevents moisture contact with steel (1 mk)
Zinc acts as a sacrificial anode, corroding before the steel does if scratched (1 mk)
4

Identify two factors that can accelerate the corrosion of iron in coastal environments. (2 marks)

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Why Practise Corrosion and prevention?

KNEC Aligned

Questions match the KCSE syllabus objectives and exam format exactly.

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