Question detail
What is a reason that mean bond enthalpy estimates can be less accurate than Hess's law values?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Energetics
Question
- A. Mean bond enthalpies are based on theoretical calculations.
- B. Hess's law is based on experimental data.
- C. Mean bond enthalpies ignore temperature effects.
- D. Hess's law does not consider bond strengths.
Answer
Hess's law is based on experimental data.
Explanation
Hess's law relies on experimental data from specific reactions, providing accurate enthalpy changes for those reactions. In contrast, mean bond enthalpies are averages derived from various compounds and do not reflect the specific conditions of a reaction. This difference in data sources leads to the potential for less accurate estimates when using mean bond enthalpies compared to the precise values obtained through Hess's law. As a result, calculations using mean bond enthalpies may not accurately represent the energy changes in a given reaction.
Common mistake
Misunderstanding Mean Bond Enthalpy
Students often confuse mean bond enthalpy with the actual enthalpy changes calculated using Hess's law.
Mean bond enthalpy is an average value that does not account for the specific molecular environment of bonds in a reaction, leading to discrepancies when compared to Hess's law calculations, which consider the actual enthalpy changes for specific reactions.
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