Question detail
Show the working for the energy transferred in 2HI -> H2 + I2 using average bond energies in Energy transfer during exothermic and endothermic reactions.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Exothermic and endothermic reactions
Question
Show the working for the energy transferred in 2HI -> H2 + I2 using average bond energies in Energy transfer during exothermic and endothermic reactions.
Answer
9 kJ. The reaction is endothermic.
Explanation
The correct option is 9 kJ, endothermic. Bonds broken: 2 × 298 = 596 kJ. Bonds formed: 1 × 436 + 1 × 151 = 587 kJ. Energy transferred = 596 - 587 = 9 kJ. The sign shows the reaction is endothermic. This supports the approved objective to evaluate uses and applications of exothermic and endothermic reactions from given information and keeps bond breaking separate from bond making in Energy transfer during exothermic and endothermic reactions.
Common mistake
Misunderstanding Applications
Students often confuse the applications of exothermic and endothermic reactions, thinking that both types are used for heating.
To fix this, students should study specific examples of each type, such as self-heating cans for exothermic reactions and sports injury packs for endothermic reactions, to understand their distinct uses.
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