Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Energetics
117 practice questions
Topics covered
- Exothermic reactions19 practice questions
- Endothermic reactions19 practice questions
- Measuring enthalpy changes of reactions19 practice questions
- Calorimetry experiments for determining the enthalpy changes of reactions18 practice questions
- Why do reactions either give out or absorb heat?19 practice questions
- Calculation of enthalpy changes of reaction using bond energies19 practice questions
Practice questions
11–20 of 51 · Easy
Question 11
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 12
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 13
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 14
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 15
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 16
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 17
1 mark · Easy
Answer and see the solution →Name the piece of apparatus commonly used to measure temperature change in a calorimetry experiment.
Question 18
3 marks · Easy
Answer and see the solution →A student investigates the enthalpy change when sodium hydroxide solution reacts with hydrochloric acid in a polystyrene cup.
(a)[1 mark]State one reason why a polystyrene cup is used in this experiment.
(b)[1 mark]Write the name of one measurement (other than temperature) the student must take to calculate the enthalpy change.
(c)[1 mark]State the name of the reaction between sodium hydroxide and hydrochloric acid.
Question 19
2 marks · Easy
Answer and see the solution →In a calorimetry experiment, 50.0 g of water absorbs 420 J of energy. Calculate the temperature rise of the water. (Specific heat capacity of water = 4.2 J/g°C)
Question 20
2 marks · Easy
Answer and see the solution →Explain why it is important to stir the solution while measuring the temperature change in a calorimetry experiment.