Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
91–100 of 188 · Normal
Question 91
3 marks · Normal
Answer and see the solution →Explain, with reasons, how you could show experimentally that manganese(IV) oxide is not chemically changed during the decomposition of hydrogen peroxide.
Question 92
4 marks · Normal
Answer and see the solution →The table shows the volume of oxygen gas collected over 60 seconds when hydrogen peroxide is decomposed using three different solids as potential catalysts. The experiment used the same conditions (temperature, concentration, volumes).
Oxygen collected over time Time (s) MnO2 (cm³) PbO2 (cm³) CuO (cm³) 0 0 0 0 20 24 8 0 40 36 13 0 60 40 16 0 (a)[2 marks]Compare the effectiveness of the three solids as catalysts for this reaction.
(b)[2 marks]Using evidence from the data, explain your answer.
Question 93
1 mark · Normal
Answer and check →Which statement best describes the role of a catalyst?
- A.A catalyst increases the rate of a reaction and is chemically unchanged at the end.
- B.A catalyst is used up during the reaction.
- C.A catalyst stops chemical reactions from taking place.
- D.A catalyst increases the yield of products in a reaction.
Question 94
2 marks · Normal
Answer and see the solution →Give two reasons why catalysts are important in industrial chemical processes.
Question 95
4 marks · Normal
Answer and see the solution →(a)[2 marks]Describe how you would set up an experiment to measure the effect of different solid catalysts on the rate of decomposition of hydrogen peroxide.
(b)[1 mark]State one safety precaution you would take when carrying out this experiment.
(c)[1 mark]What result would show that a solid is not a catalyst for this reaction?
Question 96
3 marks · Normal
Answer and see the solution →A chemistry student investigates the decomposition of hydrogen peroxide ( ) by measuring the volume of oxygen gas produced in 60 seconds, with and without a catalyst present. The results are:
Experiment Catalyst present? Volume of O produced/cm (in 60 s) 1 No 2.5 2 Yes 22.0 a) Calculate the average rate of oxygen production (in cm/s) for Experiment 1.
b) Calculate the average rate of oxygen production (in cm/s) for Experiment 2.
c) By how many times does the catalyst increase the rate of oxygen production compared to the experiment without a catalyst? Give your answer to 1 decimal place.
(a)[1 mark]Calculate the average rate of oxygen production for Experiment 1.
(b)[1 mark]Calculate the average rate of oxygen production for Experiment 2.
(c)[1 mark]By how many times does the catalyst increase the rate of oxygen production compared to the experiment without a catalyst? Give your answer to 1 decimal place.
Question 97
2 marks · Normal
Answer and see the solution →Explain, with reference to activation energy, how a catalyst affects a reaction profile diagram.
Question 98
4 marks · Normal
Answer and see the solution →The diagram below shows a reaction profile for an exothermic reaction, both with and without a catalyst.
Reaction profile diagram for part (b). (a)[1 mark]Identify which curve on the diagram represents the reaction with a catalyst.
(b)[1 mark]On the diagram, mark with a label 'Ea (with catalyst)' the activation energy for the catalysed reaction.
(c)[1 mark]State what happens to the enthalpy change (ΔH) of the reaction when a catalyst is added.
(d)[1 mark]Explain why the reaction happens faster when a catalyst is used.
Question 99
3 marks · Normal
Answer and see the solution →A reaction without a catalyst has an activation energy of 180 kJ/mol. When a catalyst is added, the activation energy decreases to 100 kJ/mol.
Calculate the difference in activation energy as a result of adding the catalyst.
Explain what this change means for the number of successful collisions.
Question 100
3 marks · Normal
Answer and see the solution →A student claims, "A catalyst lowers the energy of the reactants."
Discuss whether this statement is correct, using ideas from reaction profile diagrams and activation energy.