Question detail
For Reaction profiles, use bond energies to answer this application check: what is the energy transferred for 2HBr -> H2 + Br2?
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. 103 kJ, endothermic
- B. -103 kJ, exothermic
- C. 0 kJ, no net energy change
- D. -9 kJ, exothermic
Answer
The correct option is 103 kJ, endothermic.
Explanation
The correct option is 103 kJ, endothermic. Bonds broken: 2 × 366 = 732 kJ. Bonds formed: 1 × 436 + 1 × 193 = 629 kJ. Energy transferred = 732 - 629 = 103 kJ. The sign shows the reaction is endothermic. This application question supports the approved objective to compare the relative energies of reactants and products in exothermic and endothermic reaction profiles and keeps bond breaking separate from bond making in Reaction profiles.
Common mistake
Confusing Reactant and Product Energies
Students often confuse the energy levels of reactants and products in exothermic and endothermic reaction profiles, leading to incorrect conclusions about energy transfer.
To fix this, students should practice drawing and labeling reaction profiles, ensuring they clearly identify the energy levels of both reactants and products, and remember that in exothermic reactions, products have lower energy than reactants, while in endothermic reactions, products have higher energy.
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