Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Exothermic reactions
19 practice questions
Practice questions
1–10 of 19
Question 1
1 mark · Easy
Answer and see the solution →State what happens to the temperature of the surroundings in an exothermic reaction.
Question 2
3 marks · Easy
Answer and see the solution →The diagram below shows an incomplete energy profile for a reaction.
Energy profile diagram for a reaction (a)[1 mark]Draw a vertical arrow on the diagram to show the overall energy change for this exothermic reaction.
(b)[1 mark]Label the diagram with "activation energy" at the correct place.
(c)[1 mark]State whether the energy of the products is higher or lower than the reactants.
Question 3
2 marks · Easy
Answer and see the solution →A student mixes zinc powder with copper(II) sulfate solution. The temperature of the solution rises from 22°C to 32°C.
Calculate the temperature change in this reaction.
Question 4
2 marks · Easy
Answer and see the solution →Explain why the energy change in an exothermic reaction is shown as a downward arrow on an energy profile diagram.
Question 5
3 marks · Easy
Answer and see the solution →The table shows temperature changes observed during three different reactions:
Temperature changes in reactions Reaction Temperature change (°C) X: Neutralisation +7 Y: Potassium chloride dissolving -4 Z: Magnesium reacting with acid +10 (a)[1 mark]Which two reactions are exothermic? State their letters.
(b)[1 mark]Give a reason for your answer.
(c)[1 mark]Name one type of reaction, from those listed, that is always exothermic.
Question 6
1 mark · Easy
Answer and see the solution →In an energy profile diagram for an exothermic reaction, which has more energy: the reactants or the products?
Question 7
2 marks · Easy
Answer and see the solution →For an exothermic reaction, the reactants have an energy of 90 kJ/mol and the products have an energy of 55 kJ/mol.
Calculate the energy change (ΔH) for this reaction. State whether it is exothermic or endothermic.
Question 8
3 marks · Easy
Answer and see the solution →Some chemical reactions release energy, while others absorb energy.
(a)[1 mark]State what is meant by an exothermic reaction.
(b)[2 marks]The reaction between sodium hydroxide solution and hydrochloric acid causes the temperature of the reaction mixture to rise.
Is this reaction exothermic or endothermic? Give a reason for your answer.
Question 9
2 marks · Normal
Answer and see the solution →State whether the following reactions are exothermic or endothermic. Give a reason for each answer.
(a)[1 mark]Dissolving potassium nitrate in water causes the temperature of the solution to fall.
(b)[1 mark]Combustion of methane gas produces heat and a flame.
Question 10
4 marks · Normal
Answer and see the solution →The diagram below shows an incomplete energy profile for a chemical reaction.
Incomplete energy profile diagram for a reaction (a)[2 marks]On the diagram, draw and label:
(i) The activation energy (Ea) as an arrow.
(ii) The energy change (ΔH) as an arrow.
(b)[2 marks]State whether this reaction is exothermic or endothermic and give a reason.