Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
11–20 of 71 · Hard
Question 11
5 marks · Hard
Answer and see the solution →Describe how you would carry out a calorimetry experiment to determine the enthalpy change of a displacement reaction between magnesium and copper(II) sulfate solution in a school laboratory. Your answer should refer to apparatus, measurements, and how you would ensure reliable results.
(a)[1 mark]State the main pieces of apparatus you would use for this experiment.
(b)[2 marks]Describe the basic procedure for mixing the reactants and measuring the temperature change.
(c)[2 marks]Suggest two ways to improve the reliability or accuracy of the results in this experiment.
Question 12
2 marks · Hard
Answer and see the solution →A student adds 25.0 g of water at 22.0 °C to a beaker. After a reaction occurs, the final temperature of the water is 29.5 °C. The specific heat capacity of water is 4.18 J/g°C. Calculate the amount of heat absorbed by the water during the reaction. Give your answer in joules.
Question 13
2 marks · Hard
Answer and see the solution →A reaction is found to be exothermic overall. Explain, in terms of bond energies, why this is the case.
Question 14
5 marks · Hard
Answer and see the solution →When carbon monoxide reacts with oxygen, the following reaction occurs:
You are given the following average bond energies:
Bond Average bond energy (kJ/mol) C≡O 1072 O=O 498 C=O (in CO2) 805 (a)[2 marks]List one type of bond broken and one type of bond formed in this reaction.
(b)[1 mark]Explain why this reaction is exothermic, using bond energies.
(c)[2 marks]Calculate the enthalpy change, ΔH, for the reaction, using the bond energies in the table. Show your working and give the answer in kJ/mol (for the equation as written).
Question 15
2 marks · Hard
Answer and see the solution →Describe, in terms of bonds and energy, what happens during an endothermic reaction.
Question 16
2 marks · Hard
Answer and see the solution →The following reaction occurs:
Bond energies (in kJ/mol):
Bond Bond energy / kJ mol^{-1} H–H 436 F–F 158 H–F 565 Calculate the enthalpy change (ΔH) for the reaction using the bond energies given.
Question 17
5 marks · Hard
Answer and see the solution →Chloroethane can be made by reacting ethene with hydrogen chloride:
Bond energies (kJ/mol) Bond Bond energy / kJ mol^{-1} C=C 612 C–C 348 C–H 413 H–Cl 432 C–Cl 338 (a)[2 marks]Write down all the bonds broken and all the bonds formed in this reaction.
(b)[3 marks]Calculate the enthalpy change (ΔH), in kJ/mol, for the reaction using the bond energies provided. Show your working and give your answer to the nearest kJ/mol.
Question 18
2 marks · Hard
Answer and see the solution →A student calculates the enthalpy change for the following reaction using average bond energies:
Bond energies (kJ/mol):
Bond Bond energy / kJ mol^{-1} Cl–Cl 243 H–S 363 H–Cl 432 State the total energy required to break all the bonds in the reactants, and the total energy released when new bonds form in the products. Show your calculations.
Question 19
2 marks · Hard
Answer and see the solution →Describe one change you could make to the experiment measuring the rate of reaction between marble chips and hydrochloric acid that would allow the reaction to proceed more slowly. Explain your reasoning.
Question 20
5 marks · Hard
Answer and see the solution →A student performs an experiment to investigate the effect of temperature on the rate of reaction between marble chips and dilute hydrochloric acid. The reaction produces carbon dioxide gas, which is measured using a gas syringe. The student uses identical masses of marble chips and the same volume and concentration of acid at two different temperatures. The following data is recorded:
(a)Volume of CO₂ collected at 2 temperatures Time / min Volume of CO₂ at 20°C / cm³ Volume of CO₂ at 40°C / cm³ 0 0 0 1 18 40 2 27 60 3 31 62 4 33 62 (i)[2 marks]Calculate the average rate of reaction at 20°C in the first 2 minutes. Show your working.
(ii)[3 marks]Compare the rates of reaction at the two temperatures using the data. Give one reason, based on particle collisions, why the temperature affects the rate of reaction.