Can Calorimeters Measure Enthalpy Variation of Fast Reactions?

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Discussion Overview

The discussion revolves around the ability of calorimeters to measure the enthalpy variation of fast reactions, as raised by a participant while studying thermochemistry concepts. The scope includes theoretical considerations and practical implications related to calorimetry and reaction kinetics.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why calorimeters cannot measure the enthalpy variation of fast reactions, referencing a textbook explanation related to Hess' Law.
  • Another participant suggests that it is possible to delay reactions, implying that fast reactions might not pose a significant issue for calorimetry.
  • This participant also speculates that the rapid heat release or absorption in fast reactions could affect heat flow measurements but believes the calorimeter's thermometer would compensate for this.
  • A third participant agrees that fast reactions may not present major problems for calorimetry but highlights the challenge of measuring very slow reactions due to time constraints.

Areas of Agreement / Disagreement

Participants express differing views on the challenges posed by fast reactions in calorimetry, with some suggesting that delays can be implemented, while others acknowledge the inherent difficulties without reaching a consensus.

Contextual Notes

Participants do not fully explore the assumptions regarding the limitations of calorimetry for fast reactions, nor do they clarify the specific conditions under which measurements might be problematic.

Sonim
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TL;DR
Enthalpy , Calorimeter and Hess Law Question Related
First of all this is a question that I had while reading some concepts of my book, so this isn't a homework question. I have started reading the thermochemistry chapter of my book, and it shows the story of Hess' Law and says that it was created is because a calorimeter can't be used to measure the enthalpy variation of too slow reactions, explosive reactions, fast reaction and multi-step reactions. Why can't it be used to calculate the enthalpy variation of fast reactions ?
 
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What are your thoughts on this?
 
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Likes   Reactions: berkeman
Actually, I think the opposite. There are ways to delay reactions, so this shouldn't be a problem. Maybe it lies on the fact that fast reactions releases/absorbs heat too fast, which results in the increase of heat flow. However, it shouldn't be a problem too, because the termometer in the calorimeter would release/absorb more heat in less time as well. Have you got any idea?
 
I agree with you on the fast reactions. However, on very slow reactions, no one has the time to wait days or weeks or years for the reaction to reach equilibrium. But, otherwise, like you, I don't see major problems.
 

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