Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Rates of Reaction
164 practice questions
Topics covered
- Experiments to measure the rate of reaction19 practice questions
- Explaining what's happening19 practice questions
- Changing the surface area of the reactants19 practice questions
- Changing the concentration of the reactants19 practice questions
- Changing the pressure on the reaction19 practice questions
- What are catalysts?19 practice questions
- How does a catalyst work?20 practice questions
- Catalysts in industry19 practice questions
Practice questions
21–30 of 164
Question 21
3 marks · Easy
Answer and see the solution →The reaction between powdered iron and dilute sulfuric acid produces hydrogen gas.
(a)[1 mark]State what particles must do for a reaction to take place according to collision theory.
(b)[1 mark]Name the term for the minimum amount of energy particles need to react when they collide.
(c)[1 mark]Explain why the reaction slows down as the acid is gradually used up.
Question 22
2 marks · Easy
Answer and see the solution →Explain, using collision theory, why a reaction between magnesium ribbon and excess hydrochloric acid is faster at the start than at the end.
Question 23
3 marks · Easy
Answer and see the solution →A student observes the reaction between excess sodium carbonate and dilute hydrochloric acid. The table shows the concentration of acid over time.
Concentration of acid during reaction Time (min) Acid concentration (mol/dm³) 0 1.00 1 0.85 2 0.70 3 0.60 4 0.59 5 0.59 (a)[1 mark]Between which two times was the reaction fastest? Explain your answer.
(b)[1 mark]State why the reaction gradually slows down as shown in the table.
(c)[1 mark]According to collision theory, what needs to happen for acid particles to react with sodium carbonate?
Question 24
1 mark · Easy
Answer and see the solution →Name the theory that explains how the frequency and energy of collisions affect the rate of chemical reactions.
Question 25
3 marks · Easy
Answer and see the solution →A student investigates how fast sodium reacts with water to produce hydrogen gas at room temperature.
(a)[1 mark]State what must happen to sodium and water particles for this reaction to occur.
(b)[1 mark]According to collision theory, what is a successful collision?
(c)[1 mark]Explain why the reaction rate might change during the experiment.
Question 26
2 marks · Easy
Answer and see the solution →A reaction in a beaker starts with 50 reacting particles per cm³. After a few minutes, only 10 reacting particles per cm³ remain.
Calculate the percentage decrease in the number of reacting particles per cm³ during the reaction.
Question 27
2 marks · Easy
Answer and see the solution →In a reaction, there are 40 effective collisions per minute at the start. After some time, the number of effective collisions drops to 12 per minute.
Calculate how many times faster the reaction was at the start compared to later. Give your answer as a number.
Question 28
2 marks · Normal
Answer and see the solution →Explain why not every collision between reactant particles in a chemical reaction leads to a reaction.
Question 29
4 marks · Normal
Answer and see the solution →A student adds excess powdered magnesium to dilute hydrochloric acid in a beaker. The mixture fizzes and gives off a gas.
(a)[1 mark]State the name of the gas produced in this reaction.
(b)[3 marks]Explain, using collision theory, why the reaction is faster at the start than near the end.
Question 30
3 marks · Normal
Answer and see the solution →A student investigates the reaction between sodium thiosulfate and hydrochloric acid at two different temperatures. The reaction is much faster at 45°C than at 25°C. Explain, using collision theory, why increasing the temperature increases the rate of this reaction.