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All the reactants and products of an exothermic reaction are gaseous - CIE - A-Level Chemistry - Question 9 - 2017 - Paper 1
Question 9
All the reactants and products of an exothermic reaction are gaseous. Which statement about this reaction is correct? A The total bond energy of the products is le... show full transcript
Worked Solution & Example Answer:All the reactants and products of an exothermic reaction are gaseous - CIE - A-Level Chemistry - Question 9 - 2017 - Paper 1
Step 1
The total bond energy of the products is more than the total bond energy of the reactants, and ΔH for the reaction is negative.
Answer
In an exothermic reaction, energy is released when bonds are formed in the products. This means that the total bond energy of the products must be lower than that of the reactants because energy has been released as heat. Therefore, for an exothermic reaction, ΔH is negative, indicating that energy has been released to the surroundings. Hence, statement C is incorrect.
Statement A correctly asserts that the bond energy of the products is less than that of the reactants and that ΔH is negative, making it the correct option.