Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
281–290 of 442
Question 281
7 marks · Hard
Answer and see the solution →A researcher investigates the decomposition of hydrogen peroxide to oxygen gas. She runs two versions of the experiment: one at low pressure without a catalyst, the other at high pressure with a catalyst.
(a)[1 mark]Describe what is meant by the term 'catalyst'.
(b)[2 marks]Explain how increasing the pressure affects the rate of the decomposition of hydrogen peroxide when both hydrogen peroxide and oxygen are in the gas phase.
(c)[4 marks]The table gives the results for two versions of the reaction:
Experiment Pressure Catalyst Time to collect 20 cm³ O₂ / s 1 low none 120 2 high manganese(IV) oxide 20 Compare the time taken to collect the same volume of oxygen in the two experiments. Explain your answer in terms of the effects of both pressure and the catalyst.
Question 282
1 mark · Easy
Answer and see the solution →State one characteristic of a system at dynamic equilibrium.
Question 283
3 marks · Easy
Answer and see the solution →The thermal decomposition of calcium carbonate is shown below:
(a)[1 mark]Identify the symbol in the equation that shows the reaction is reversible.
(b)[1 mark]Write the name of the product formed as a gas in this reaction.
(c)[1 mark]Rewrite the equation to represent this reaction as a reversible reaction.
Question 284
2 marks · Easy
Answer and see the solution →At dynamic equilibrium in a sealed container, the rate of the forward reaction is 0.12 mol/min. Calculate the rate of the backward reaction. State your answer and give a reason.
Question 285
2 marks · Easy
Answer and see the solution →Explain why the concentration of reactants does not change once a reversible reaction has reached dynamic equilibrium in a sealed container.
Question 286
3 marks · Easy
Answer and see the solution →The table below shows the amount of solid and gas present in a sealed container at different times during a chemical reaction.
Amounts in a sealed reaction vessel over time Time (min) Solid (g) Gas (g) 0 5.0 0.0 2 4.2 0.8 4 3.9 1.1 6 3.9 1.1 (a)[1 mark]Between which times does the reaction reach equilibrium?
(b)[1 mark]Give one piece of evidence from the table for your answer to (a).
(c)[1 mark]Write a word or chemical equation for the reversible reaction that could be occurring.
Question 287
1 mark · Easy
Answer and see the solution →State the condition required for a reversible reaction to reach dynamic equilibrium.
Question 288
3 marks · Easy
Answer and see the solution →A reversible reaction between two gases in a sealed container reaches dynamic equilibrium.
(a)[1 mark]State what happens to the concentration of each gas at equilibrium.
(b)[2 marks]Explain why the concentrations behave this way at dynamic equilibrium.
Question 289
2 marks · Easy
Answer and see the solution →The dehydration of hydrated copper(II) sulfate crystals is a reversible reaction:
If 0.50 mol of is heated, how many moles of water are produced? Show your working.
Question 290
2 marks · Normal
Answer and see the solution →Hydrated cobalt(II) chloride can be heated to produce anhydrous cobalt(II) chloride and water. The process is reversible.
State the chemical equation for this reversible reaction, using the correct symbol, and explain what the symbol means.