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
91–100 of 117
Question 91
4 marks · Normal
Answer and see the solution →Read the following reaction:
You are given these average bond energies (kJ/mol): S=O = 523, O=O = 498
a) Write down all bonds that are broken and formed during the reaction.
b) Explain, using these bond energies, what determines whether the reaction is exothermic or endothermic.
(a)[2 marks]List all bonds broken and formed.
(b)[2 marks]Explain, using bond energies, what determines if the reaction is exothermic or endothermic.
Question 92
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 93
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 94
2 marks · Hard
Answer and see the solution →Describe, in terms of bonds and energy, what happens during an endothermic reaction.
Question 95
1 mark · Easy
Answer and see the solution →What is the meaning of the term 'bond energy'?
Question 96
3 marks · Easy
Answer and see the solution →(a)[1 mark]State whether bond breaking is exothermic or endothermic.
(b)[1 mark]State whether bond making is exothermic or endothermic.
(c)[1 mark]Explain your answer to part b.
Question 97
2 marks · Easy
Answer and see the solution →Calculate the enthalpy change (ΔH) for the following reaction using the bond energies given below: Bond energies (kJ/mol):
Bond Bond energy / kJ mol^{-1} H–H 436 Br–Br 193 H–Br 366 Question 98
2 marks · Easy
Answer and see the solution →Explain why a reaction is exothermic in terms of bond energies.
Question 99
3 marks · Easy
Answer and see the solution →The table below gives bond energies (kJ/mol):
Bond Bond energy / kJ mol^{-1} C–C 151 C–H 413 H–H 436 Use these values to answer the following about the reaction:
(a)[1 mark]List all the bonds broken and all formed in this reaction.
(b)[1 mark]Calculate the total energy required to break bonds in the reactant.
(c)[1 mark]Calculate the enthalpy change (ΔH) for the reaction.
Question 100
1 mark · Easy
Answer and see the solution →State the unit in which bond energy is measured.