Rates of reaction — KCSE Chemistry
KCSE Chemistry · 46 practice questions · 4 syllabus objectives
What You'll Learn
Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.
Define rate of reaction and describe methods of measuring reaction rate (gas volume, mass change, colour change)
Explain how concentration, temperature, surface area and catalysts affect the rate of reaction using collision theory
Interpret graphs of rate of reaction and calculate average rate from gradient or volume/time data
Rates of reaction
Sample Questions
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In an experiment to measure the rate of reaction between zinc granules and dilute hydrochloric acid by mass loss, a cotton wool plug is placed at the mouth of the flask. (a) State the role of the cotton wool plug. (1 mark) (b) Explain why the cotton wool plug does not prevent the loss of mass. (1 mark) (c) Suggest why a rubber bung would NOT be suitable instead of cotton wool. (1 mark)
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In an experiment to measure the rate of reaction between magnesium ribbon and dilute hydrochloric acid by mass loss, a cotton wool plug is placed at the mouth of the flask. (a) State the role of the cotton wool plug. (1 mark) (b) Explain why the cotton wool plug does not prevent the loss of mass. (1 mark) (c) Suggest why a rubber bung would NOT be suitable instead of cotton wool. (1 mark)
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In an experiment to measure the rate of reaction between marble chips (CaCO₃) and dilute hydrochloric acid by mass loss, a cotton wool plug is placed at the mouth of the flask. (a) State the role of the cotton wool plug. (1 mark) (b) Explain why the cotton wool plug does not prevent the loss of mass. (1 mark) (c) Suggest why a rubber bung would NOT be suitable instead of cotton wool. (1 mark)
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Marble chips (CaCO₃) are placed in dilute hydrochloric acid in an open beaker on a balance. (a) Write the equation for the reaction. (1 mark) (b) Explain why there is a continuous loss of mass during the reaction. (2 marks) (c) Explain why the mass eventually remains constant. (1 mark)
Why Practise Rates of reaction?
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