Variation in mass and binding energy in nuclear reactions

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Homework Help Overview

The discussion revolves around the energetics of nuclear reactions, specifically focusing on fission and fusion processes. The original poster expresses confusion regarding the binding energy per nucleon in these reactions and seeks clarification on the validity of two statements related to binding energy and mass changes during these processes.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to understand the relationship between binding energy and mass in nuclear reactions, questioning the correctness of two statements regarding fission and fusion. Some participants affirm the correctness of these statements for energy-releasing reactions while noting exceptions. Others raise questions about the application of total energy in this context and the implications of the sign convention for binding energy.

Discussion Status

The discussion is active, with participants providing insights and affirmations regarding the original poster's statements. There is an exploration of different scenarios, including reactions that do not release energy. Some guidance has been offered on considering total energy, although questions remain about the application of the sign convention.

Contextual Notes

Participants are navigating the complexities of binding energy and mass in nuclear reactions, with some expressing difficulty in visualizing these concepts. The discussion includes references to specific conditions under which reactions may or may not release energy.

Krushnaraj Pandya
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Homework Statement


I'm perpetually confused keeping track of the energetics of a nuclear reaction and I broke down my conceptual questions into the following parts
statement a-In a fission reaction, the two medium sized daughter nuclei each have more binding energy per nucleon than the original nucleus
statement b-In a fusion reaction the heavier nucleus has more binding energy per nucleon than the lighter ones

Which of these statements are correct and why, I know that mass of the reactants is always higher (the loss in mass is released as energy) and total binding energy of reactants is always lower (I can't visualize this very well) for a spontaneous reaction but I can't figure out the validity of the above statements and I'd really appreciate some help with that-thank you.

Homework Equations


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The Attempt at a Solution


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Both statements are correct for reactions that release energy. There are also reactions that do not. You can e.g. fuse heavy nuclei with an accelerator delivering the necessary energy.
Krushnaraj Pandya said:
and total binding energy of reactants is always lower (I can't visualize this very well)
The sign convention for binding energy is a bit unfortunate.

If in doubt you can always consider the total energy.
 
mfb said:
Both statements are correct for reactions that release energy. There are also reactions that do not. You can e.g. fuse heavy nuclei with an accelerator delivering the necessary energy.The sign convention for binding energy is a bit unfortunate.

If in doubt you can always consider the total energy.
How can we use total energy without using the sign convention for binding energy?
 
Do you mean to say we'd use rest mass*c^2 of reactants+ KE due to any velocity =rest mass of products*c^2 +KE
 
That always works, sure.
 
mfb said:
That always works, sure.
Alright, thank you very much :D
 

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