Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
61–70 of 188 · Normal
Question 61
1 mark · Normal
Answer and check →Which statement best explains why a reaction only occurs when particles collide with at least the activation energy?
- A.It allows more particles to react with each other at low temperatures.
- B.It provides enough energy to break existing bonds for the reaction to occur.
- C.It increases the frequency of collisions between reactant particles.
- D.It makes the product more stable after the reaction.
Question 62
2 marks · Normal
Answer and see the solution →State the two conditions that must be met for a collision between reactant particles to lead to a reaction, according to collision theory.
Question 63
4 marks · Normal
Answer and see the solution →A reaction between excess zinc and dilute sulfuric acid is carried out in a conical flask. The total volume of hydrogen gas produced is measured.
(a)[1 mark]State one way the rate of this reaction could be increased without changing the temperature.
(b)[3 marks]Explain your answer to part (a) using collision theory.
Question 64
3 marks · Normal
Answer and see the solution →A student reacts marble chips (calcium carbonate) with dilute hydrochloric acid in a beaker. At the start, there are 60 acid particles per cm³ in the solution. Every second, about 18 of these particles collide with the marble chips. Only 5 of these collisions have enough energy to result in a reaction and are called successful collisions.
(a)[2 marks]Calculate the percentage of collisions that are successful each second at the start of the reaction.
(b)[1 mark]Explain, using collision theory, what happens to the rate of reaction as the number of acid particles falls during the experiment.
Question 65
2 marks · Normal
Answer and see the solution →A student reacts powdered calcium carbonate with dilute hydrochloric acid. Explain why the reaction happens faster than if the same mass of calcium carbonate is in large lumps, not powder.
Question 66
4 marks · Normal
Answer and see the solution →Solid magnesium ribbon reacts with dilute sulfuric acid to produce hydrogen gas. A student wants to investigate how changing the surface area of magnesium affects the rate of reaction.
(a)[1 mark]Describe a change the student could make to increase the surface area of magnesium used.
(b)[2 marks]Explain how this change affects the rate of the reaction.
(c)[1 mark]State one variable other than surface area that should be kept constant in this investigation.
Question 67
3 marks · Normal
Answer and see the solution →A student conducts two experiments: - Experiment 1: 5.0 g of marble chips (large lumps) - Experiment 2: 5.0 g marble powder Both react with identical volumes and concentrations of dilute hydrochloric acid at the same temperature. In Experiment 1, all the marble has reacted in 7 minutes. In Experiment 2, the reaction is complete in 2 minutes.
Calculate the average rate of reaction in grams of marble reacted per minute for: (a) Experiment 1 (b) Experiment 2.
Question 68
3 marks · Normal
Answer and see the solution →A factory grinds solid reactants used in a chemical process into fine powder instead of using large lumps. Explain, with reasons, how and why this affects the rate of the reaction.
Question 69
4 marks · Normal
Answer and see the solution →The table shows the total volume of gas produced over time when excess hydrochloric acid reacts separately with two forms of zinc of the same mass: powder and large granules.
Volume of gas produced (cm³) Time (min) Zinc powder (cm³) Zinc granules (cm³) 0 0 0 1 38 15 2 65 25 3 85 32 4 90 39 5 90 43 6 90 44 (a)[1 mark]Describe the difference in the rate of reaction between the powder and granules during the first 3 minutes.
(b)[1 mark]Give the total volume of gas produced at the end of both reactions.
(c)[1 mark]Explain why both forms of zinc produced the same final volume of gas.
(d)[1 mark]Explain why the reaction with zinc powder is faster.
Question 70
1 mark · Normal
Answer and check →Which change will increase the rate of a reaction between a solid and a liquid most effectively?
- A.Grinding the solid into a powder.
- B.Decreasing the temperature.
- C.Using less of the liquid.
- D.Stirring less frequently.