Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
51–60 of 183 · Easy
Question 51
5 marks · Easy
Answer and see the solution →Magnesium reacts with dilute hydrochloric acid in a reaction described below:
The reaction is exothermic. An energy profile for this reaction is shown below, but the axes and key features have not been labelled.
(a)Incomplete energy profile diagram for: \ce{Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)} (i)[2 marks]On the diagram, clearly label: - the correct position of the reactants and products; - the activation energy; - the enthalpy change (ΔH), with an arrow showing its direction.
(b)In a second experiment, a student dissolves ammonium chloride (NH₄Cl) in water. She uses 50.0 g of water at 24.0°C. After the salt dissolves, the final temperature is 19.7°C. The specific heat capacity, c, of water is 4.18 J/(g°C).
Calculate the heat energy change (Q) for the dissolving process. State if the reaction is exothermic or endothermic, and explain your answer.
(i)[2 marks]Calculate the heat energy change, Q, for this process. Give the unit.
(ii)[1 mark]State if this process is exothermic or endothermic and explain your answer.
Question 52
1 mark · Easy
Answer and see the solution →State one factor that can be changed to investigate its effect on the rate of a reaction between a solid and a liquid.
Question 53
3 marks · Easy
Answer and see the solution →A student is investigating how the concentration of hydrochloric acid affects the rate of reaction with excess marble chips. The student collects the gas produced during the reaction.
(a)[1 mark]Name the gas produced in this reaction.
(b)[1 mark]State a piece of equipment the student can use to measure the volume of this gas.
(c)[1 mark]Explain why marble chips are added in excess, rather than using the exact amount needed for the acid.
Question 54
2 marks · Easy
Answer and see the solution →In an experiment, a student collects 36 cm³ of carbon dioxide gas in 3 minutes. Calculate the average rate of reaction in cm³/min.
Question 55
2 marks · Easy
Answer and see the solution →Explain how increasing the temperature affects the rate of a reaction between a solid and a solution. Give two reasons for your answer.
Question 56
3 marks · Easy
Answer and see the solution →The table below shows part of an experiment where the mass of carbon dioxide lost was measured every minute as marble chips reacted with dilute hydrochloric acid.
Time / min Mass of CO2 lost / g 0 0.00 1 0.38 2 0.59 3 0.68 4 0.71 (a)[1 mark]Calculate the average rate of reaction between 1 and 2 minutes, giving your answer in g/min.
(b)[1 mark]At which time interval was the reaction fastest? Give your reasoning.
(c)[1 mark]Suggest one practical reason why the mass measured might not decrease exactly as expected.
Question 57
1 mark · Easy
Answer and see the solution →State the name of the solid reactant used in the reaction with hydrochloric acid to produce carbon dioxide gas.
Question 58
3 marks · Easy
Answer and see the solution →A student performs an experiment to investigate how a catalyst affects the rate of decomposition of hydrogen peroxide solution. The student uses different solids as possible catalysts.
(a)[1 mark]State the name of the gas collected during the decomposition of hydrogen peroxide.
(b)[1 mark]Give one method by which the rate of gas production can be measured in this experiment.
(c)[1 mark]Suggest why different solids may produce different rates of reaction.
Question 59
2 marks · Easy
Answer and see the solution →A reaction produces 80 cm³ of carbon dioxide in 4 minutes. Calculate the average rate of reaction in cm³/min.
Question 60
1 mark · Easy
Answer and see the solution →State the minimum condition that must be met for a chemical reaction to occur between two particles, according to collision theory.