Does Chemical Reactions Affect Mass?

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Discussion Overview

The discussion centers on whether the mass of compounds changes during exothermic and endothermic chemical reactions, exploring both theoretical implications and practical measurements. The scope includes conceptual and technical aspects of chemistry and physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the mass of compounds does change during chemical reactions, but the difference is typically undetectable by most instruments.
  • Others argue that chemically, the mass does not change, indicating a disagreement on the fundamental nature of mass in chemical processes.
  • One participant introduces the concept of binding energy changes in electrons during reactions, suggesting that these changes could influence the mass of the system, although they note that the mass defect is very small in chemical reactions compared to nuclear reactions.
  • There is a mention of the analogy between electromagnetic forces in chemistry and nuclear processes, highlighting the complexity of the topic.

Areas of Agreement / Disagreement

Participants express differing views on whether mass changes occur during chemical reactions, with no consensus reached on the matter.

Contextual Notes

The discussion highlights the limitations in measuring mass changes due to the small scale of binding energy differences in chemical reactions compared to nuclear reactions.

pixel01
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Does mass of compounds change due to exothermic/endothermic chemical reactions?
 
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This is not the chemistry sub-forum *hint* ;-)
 
pixel01 said:
Does mass of compounds change due to exothermic/endothermic chemical reactions?

Yes but. The difference in mass is undetectable by almost all instruments.
 
malawi_glenn said:
This is not the chemistry sub-forum *hint* ;-)

Chemically, the answer is definitely NOT, that's why I ask here.
 
Well chemistry processes are that the electrons are chaning orbits, so that their binding energy is released or increased -> which influences the mass of the system under consideration. It is the EM- force analogy with fusion and fission in Nuclear physics.

But the binding energies of electrons in atoms and molecules are of the order eV (!) so it is very tiny mass defect, just as mathman said.
The binding energies in nuclei are of the order MeV, so there the consequenses are bigger.
 

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