Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Endothermic reactions
19 practice questions
Practice questions
1–10 of 19
Question 1
1 mark · Easy
Answer and see the solution →State the symbol and unit used for the enthalpy change of a reaction.
Question 2
3 marks · Easy
Answer and see the solution →(a)[1 mark]What does a negative value for ΔH indicate about a chemical reaction?
(b)[1 mark]Name one observable change you would expect in the surroundings during this reaction.
(c)[1 mark]Give an example, including a balanced equation with ΔH, for a type of reaction that has a negative enthalpy change.
Question 3
2 marks · Easy
Answer and see the solution →A reaction absorbs 45 kJ of heat energy when exactly 1.5 mol of the substance react completely. Calculate the enthalpy change, ΔH, for this reaction in kJ/mol. State your answer with the correct sign.
Question 4
2 marks · Easy
Answer and see the solution →Explain why energy must be supplied to the reactants in an endothermic reaction. Refer to the relative energies of reactants and products in your answer.
Question 5
3 marks · Easy
Answer and see the solution →The table shows the enthalpy changes for dissolving three different salts in water.
Enthalpy changes for dissolving salts in water Salt ΔH (kJ/mol) Potassium nitrate +34 Calcium chloride –81 Ammonium chloride +15 (a)[1 mark]Which salt dissolving is the most exothermic? Give a reason for your answer.
(b)[1 mark]Which salt dissolving is the most endothermic? State the value of ΔH for this salt.
(c)[1 mark]Explain what the positive sign of ΔH tells you about the dissolving process for ammonium chloride.
Question 6
1 mark · Easy
Answer and see the solution →Describe what you would feel if you held a container where an endothermic reaction is taking place.
Question 7
3 marks · Easy
Answer and see the solution →(a)[1 mark]Name the term that describes the total heat energy change during a chemical reaction.
(b)[2 marks]A chemical change absorbed 74 kJ when 2.0 mol of reactant were used. Calculate the enthalpy change, ΔH, in kJ/mol. Show your calculation.
Question 8
2 marks · Easy
Answer and see the solution →In a laboratory experiment, a reaction gave out 120 kJ of heat when 4.0 mol of the substance were used. Calculate the enthalpy change, ΔH, for this reaction in kJ/mol. Include the correct sign in your answer.
Question 9
4 marks · Normal
Answer and see the solution →Hydrated copper(II) sulfate is dissolved in water in a polystyrene cup. The temperature drops from 22.5 °C to 18.0 °C.
(a)[2 marks]State whether this reaction is endothermic or exothermic and explain how you know.
(b)[1 mark]Calculate the temperature change for this reaction.
(c)[1 mark]Suggest how the enthalpy change () of this reaction could be calculated, naming any values that would be needed.
Question 10
3 marks · Normal
Answer and see the solution →When 0.015 mol of ammonium nitrate (NH₄NO₃) dissolves in 40.0 g of water, the temperature falls by 5.8 °C. The specific heat capacity of water is 4.18 J g⁻¹ °C⁻¹.
Calculate the enthalpy change, ΔH, for the dissolution of ammonium nitrate in kJ/mol. Give your answer to two decimal places.