Question detail
Bond-making check. In The energy change of reactions (HT only), a question asks what happens when product bonds form. Which conclusion best supports HT only?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Exothermic and endothermic reactions
Question
- A. Bond-making check: Energy is released when bonds form in the products.
- B. Energy must always be supplied when product bonds form.
- C. Bond making is unrelated to overall energy change.
- D. Bond making only happens in fuel cells.
Answer
The correct option is Bond-making check: Energy is released when bonds form in the products..
Explanation
The correct option is Bond-making check: Energy is released when bonds form in the products.. This scenario keeps the answer anchored to The energy change of reactions (HT only) in Exothermic and endothermic reactions. It supports HT only without repeating the same wording as nearby Energy changes questions, and it separates exothermic, endothermic, activation-energy, bond-energy, cell and fuel-cell ideas.
Common mistake
Confusing bond‑energy calculations with reaction‑profile interpretation
Students think that the shape of a reaction profile can be used to calculate the exact energy change of a reaction, or that the activation energy shown on the profile is the same as the bond energies used in calculations.
Explain that a reaction profile is a qualitative diagram showing the relative energies of reactants, transition state and products, and that it cannot provide numerical bond‑energy values. Bond‑energy calculations use tabulated average energies for specific bonds to determine the overall energy change, while a reaction profile only indicates whether a reaction is exothermic or endothermic and the relative size of the activation energy.
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