Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
81–90 of 188 · Normal
Question 81
2 marks · Normal
Answer and see the solution →State what happens to the rate of a reaction involving gases when the pressure is increased. Briefly explain your answer.
Question 82
4 marks · Normal
Answer and see the solution →(a)[1 mark]A student increases the pressure in a chemical reaction involving only solids. Predict what effect, if any, this has on the rate of reaction.
(b)[2 marks]Explain why changing the pressure has little effect on the rate of reaction for solids. Use particle arrangement in your answer.
(c)[1 mark]Would increasing the pressure have a similar effect on a reaction involving only liquids? Explain your answer.
Question 83
3 marks · Normal
Answer and see the solution →A reaction between two gases at 100 kPa takes 10 minutes to complete. If the pressure is increased to 200 kPa, assume the rate doubles. Calculate the new time for the reaction to complete.
Show your working.
Question 84
3 marks · Normal
Answer and see the solution →Explain, using particle theory, why changing the pressure has little effect on the rate of reactions involving only liquids.
Question 85
4 marks · Normal
Answer and see the solution →The table below shows the time taken for a reaction between two gases at different pressures.
Reaction time at different pressures Pressure (kPa) Time to complete reaction (s) 50 40 100 20 200 10 (a)[1 mark]Describe how the time taken changes as the pressure increases.
(b)[2 marks]Calculate how many times faster the reaction is at 200 kPa compared to 50 kPa.
(c)[1 mark]Explain why the reaction is faster at higher pressures.
Question 86
1 mark · Normal
Answer and check →Which statement best explains why increasing the pressure of a reaction involving only liquids has little effect on the rate?
- A.Liquid particles are already close together, so increasing pressure does not significantly increase the number of collisions.
- B.Increasing pressure causes liquids to evaporate quickly.
- C.Higher pressure breaks down liquid molecules.
- D.Liquids expand a lot when pressure changes.
Question 87
2 marks · Normal
Answer and see the solution →Describe the effect of increasing the pressure on a reaction between two gases, and link your answer to particle collisions.
Question 88
4 marks · Normal
Answer and see the solution →(a)[1 mark]State whether changing the pressure has a significant effect on the rate of reaction for solids or liquids.
(b)[2 marks]Describe the arrangement of particles in solids and in liquids.
(c)[1 mark]Explain, using your answer to (b), why pressure does not change the rate much for solids and liquids.
Question 89
2 marks · Normal
Answer and see the solution →State what a catalyst is and explain why the same catalyst can be used again in another reaction of the same type.
Question 90
4 marks · Normal
Answer and see the solution →(a)[2 marks]Write a word equation and a balanced symbol equation for the catalytic decomposition of hydrogen peroxide.
(b)[2 marks]Explain why manganese(IV) oxide is described as a catalyst in this reaction.