Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
181–183 of 183 · Easy
Question 181
7 marks · Easy
Answer and see the solution →A student carries out an experiment to investigate the effect of surface area on the rate of reaction between excess powdered calcium carbonate and 50 cm³ of hydrochloric acid at 2.00 mol/dm³. The loss in mass, due to carbon dioxide being produced, is measured every 30 seconds. The experiment uses a conical flask as shown.
(a)[2 marks]Describe how you could carry out this experiment to measure the rate of carbon dioxide production.
(b)In a second experiment, the student repeats the reaction using the same amount of powdered calcium carbonate and acid, but keeps the flask sealed with a stopper and a delivery tube connected to an inverted measuring cylinder filled with water, to collect the gas formed.
The volume of carbon dioxide produced in the first minute is 45 cm³.
(i)[1 mark]Calculate the average rate of reaction (in cm³/s) for the first minute.
(ii)[1 mark]State one way in which the method used in this experiment allows the rate to be measured more accurately than using just a balance.
(c)[3 marks]The student then investigates the following gas-phase reversible reaction in a sealed container:
Predict and explain how increasing the pressure will affect the position of equilibrium of this reaction.
Question 182
7 marks · Easy
Answer and see the solution →Catalysts are widely used in industry to speed up chemical reactions. Some industrial reactions are also reversible and take place in sealed containers.
(a)[1 mark]State one reason why catalysts are important in industrial chemical reactions.
(b)[1 mark]Copper(II) sulfate can be used in a reversible reaction in a sealed test tube: What is meant by a 'sealed container' in the context of a reversible reaction? (Give one feature of a sealed container relevant to the reaction above.)
(c)[2 marks]Ammonia is produced by reacting nitrogen and hydrogen using an iron catalyst, in a sealed reactor. Explain how using a catalyst benefits the ammonia production process, apart from cost.
(d)[2 marks]Describe how you could show experimentally that a catalyst is not used up in a reaction.
(e)[1 mark]Give one feature of a sealed container that makes it suitable for studying reversible reactions.
Question 183
7 marks · Easy
Answer and see the solution →This question is about catalysts and the effect of temperature on reversible reactions.
(a)[3 marks]Draw a reaction profile diagram for an exothermic reaction. Clearly label the following on your diagram:
- Reactants - Products - Activation energy (with and without catalyst) - ΔH (enthalpy change)
(b)[2 marks]A reversible reaction takes place:
Explain what happens to the position of equilibrium if the temperature is increased. State your answer in terms of exothermic and endothermic reaction direction.
(c)[2 marks]State whether adding a catalyst will change the position of equilibrium in this reaction. Explain your answer.