Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
121–130 of 183 · Easy
Question 121
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 122
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 123
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 124
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 125
1 mark · Easy
Answer and see the solution →State the condition required for a reversible reaction to reach dynamic equilibrium.
Question 126
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 127
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 128
3 marks · Easy
Answer and see the solution →This question is about sealed containers and reversible reactions.
(a)[1 mark]State what a sealed container means in the context of a chemical reaction.
(b)[1 mark]Give one reason why using a sealed container is important when studying reversible reactions.
(c)[1 mark]Suggest one thing that is allowed to change in a sealed container during a reaction.
Question 129
2 marks · Easy
Answer and see the solution →The thermal decomposition of solid ammonium chloride is a reversible reaction.
Explain why both ammonia and hydrogen chloride gases are observed inside the sealed tube during heating, and why a white solid appears again above the heated area.
Question 130
3 marks · Easy
Answer and see the solution →A student records the number of red and green squares at different times in a sealed container during a reversible reaction.
Time (s) Red squares Green squares 0 40 0 1 30 10 2 23 17 3 19 21 (a)[1 mark]How many total squares are there in the container at each recorded time?
(b)[1 mark]What does this suggest about the system in the container?
(c)[1 mark]State what feature of the container ensures this result in a reversible reaction.