Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Changing the surface area of the reactants
19 practice questions
Practice questions
1–3 of 3 · Hard
Question 1
2 marks · Hard
Answer and see the solution →A student investigates the reaction between magnesium and dilute hydrochloric acid. She uses two samples of magnesium of identical mass: one as a single strip and the other cut into many tiny pieces. State and explain how the rate of reaction will differ between the two samples.
Question 2
5 marks · Hard
Answer and see the solution →A student conducts an experiment to discover how changing the surface area of a solid affects the rate of its reaction with a liquid. She reacts 4.0 g of zinc with 25 cm³ of excess dilute sulfuric acid. She performs the same reaction twice:
(a)[2 marks]Describe a safe method she could use to compare the reaction rate using zinc granules and zinc powder, and state a measurement that would provide evidence for which reaction is faster.
(b)[2 marks]Explain, in terms of particle collisions, why the reaction rate changes when using zinc powder instead of granules.
(c)[1 mark]Suggest one other variable, apart from surface area, that must be kept the same to ensure a fair comparison.
Question 3
2 marks · Hard
Answer and see the solution →Explain, using collision theory, why a powdered solid reacts more quickly with a liquid than the same mass of solid in one lump.