Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
21–30 of 188 · Normal
Question 21
4 marks · Normal
Answer and see the solution →A student measures the temperature change when potassium nitrate dissolves in water in a calorimeter. The data is shown below:
Time (min) Temperature (°C) 0 20.0 1 19.1 2 19.1 3 19.2 (a)[1 mark]Describe how the temperature of the solution changes during the experiment.
(b)[1 mark]Calculate the overall temperature change from 0 to 1 minute.
(c)[1 mark]What type of reaction is occurring? Explain using the data.
(d)[1 mark]Suggest why the temperature remains almost constant after 1 minute.
Question 22
1 mark · Normal
Answer and check →Which of the following changes would most improve the accuracy of a calorimetry experiment measuring enthalpy change?
- A.Using a glass beaker instead of a polystyrene cup
- B.Measuring the temperature change quickly after mixing
- C.Leaving the calorimeter uncovered during the reaction
- D.Using a wooden stirring rod to mix the solution
Question 23
2 marks · Normal
Answer and see the solution →Give two reasons why repeated trials are useful in calorimetry experiments.
Question 24
4 marks · Normal
Answer and see the solution →A student is investigating the enthalpy change for the reaction:
They use a polystyrene cup as a calorimeter.
(a)[2 marks]Draw a labelled diagram of the calorimeter setup.
(b)[2 marks]State two reasons why a polystyrene cup is used instead of a glass beaker.
Question 25
2 marks · Normal
Answer and see the solution →Describe how you would measure the enthalpy change of solution for a solid salt dissolving in water using a simple calorimetry experiment. Include two key steps in your answer.
Question 26
4 marks · Normal
Answer and see the solution →A student carries out a calorimetry experiment to find the amount of heat released in a neutralisation reaction between hydrochloric acid and sodium hydroxide. She mixes 50 g of solution at 21.0°C with sodium hydroxide. After the reaction, the temperature rises to 27.5°C. The specific heat capacity of water is 4.18 J/g°C.
(a)[1 mark]Calculate the temperature change (ΔT) of the solution.
(b)[1 mark]Write the equation used to calculate the heat energy change (Q) in this experiment.
(c)[2 marks]Calculate the total heat energy, in joules, released in this reaction. Show your working.
Question 27
3 marks · Normal
Answer and see the solution →In a calorimetry experiment, 1.25 g of magnesium reacts completely with excess hydrochloric acid. The temperature of the 100 g acid solution rises by 9.8°C. The specific heat capacity of the solution is 4.18 J/g°C. Calculate the molar enthalpy change (ΔH) of this reaction in kJ/mol. The relative atomic mass of magnesium, Mg, is 24.
Question 28
3 marks · Normal
Answer and see the solution →A student finds that their calculated enthalpy change of combustion for ethanol is much less exothermic than the value from data books. Explain three possible sources of error in their calorimetry experiment that could have led to this result.
Question 29
4 marks · Normal
Answer and see the solution →The table shows some data from a calorimetry experiment measuring the enthalpy change of a displacement reaction between iron and copper(II) sulfate:
Data from calorimetry experiment Volume of copper(II) sulfate solution / cm³ Mass of iron used / g Initial temperature / °C Maximum temperature / °C Specific heat capacity / J/g°C 60 2.4 18.4 24.7 4.18 (a)[1 mark]Calculate the temperature change (ΔT) for this reaction.
(b)[2 marks]Assume the density of the solution is 1 g/cm³. Calculate the heat energy change, Q, in joules.
(c)[1 mark]Suggest one assumption made in this calculation.
Question 30
1 mark · Normal
Answer and check →Which value must be measured directly in a calorimetry experiment in order to calculate the heat energy released using the equation Q = mcΔT?
- A.The temperature change of the water
- B.The pressure inside the calorimeter
- C.The colour of the solution
- D.The rate of reaction