Energy change in a nuclear reaction

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Homework Help Overview

The discussion revolves around the energy change in a nuclear reaction involving fluorine-18 capturing a proton to produce neon-19. Participants are exploring the concept of mass defect and its implications for energy release or absorption in nuclear processes.

Discussion Character

  • Conceptual clarification, Assumption checking, Mixed

Approaches and Questions Raised

  • Participants are attempting to understand the definition of mass defect and its relation to energy changes in nuclear reactions. There are questions about whether the energy is released or absorbed based on the mass defect values of the reactants and products.

Discussion Status

The discussion is actively exploring different interpretations of mass defect and its implications for energy conservation. Some participants are providing clarifications and engaging in a back-and-forth about the definitions and meanings of mass defect in the context of the reaction.

Contextual Notes

Participants are working with specific mass defect values and are questioning the assumptions related to energy changes in the reaction. There is an emphasis on understanding the relationship between mass defect and binding energy without reaching a definitive conclusion.

songoku
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Homework Statement
A fluorine - 18 nucleus can capture proton producing a neon - 19 nucleus as the product. The mass defect of fluorine - 18 and neon - 19 are 0.14712 u and 0.15398 u respectively. What is the energy change associated with this reaction?
Relevant Equations
E = mc^2
I got 6.5 MeV but I don't understand how to determine whether the energy is released or absorbed. My guess: the energy is absorbed because mass defect of neon is bigger?

Thanks
 
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songoku said:
Homework Statement:: A fluorine - 18 nucleus can capture proton producing a neon - 19 nucleus as the product. The mass defect of fluorine - 18 and neon - 19 are 0.14712 u and 0.15398 u respectively. What is the energy change associated with this reaction?
Homework Equations:: E = mc^2

I got 6.5 MeV but I don't understand how to determine whether the energy is released or absorbed. My guess: the energy is absorbed because mass defect of neon is bigger?

Thanks
What is your understanding of how mass defect is defined?
 
haruspex said:
What is your understanding of how mass defect is defined?

Difference between total mass of products and parents because some of the masses are converted to energy
 
songoku said:
Difference between total mass of products and parents because some of the masses are converted to energy
That's ambiguous because a difference is unsigned, and when given as the mass defect of an atom it is not in respect of an arbitrary disassemblage. Can you be more precise?
 
I think the more appropriate definition of mass defect is the total mass of proton and neutron minus mass of the nuclei
 
songoku said:
I think the more appropriate definition of mass defect is the total mass of proton and neutron minus mass of the nuclei
Right, so has the mass defect (of the whole system) increased or decreased? What does that mean about the change in total mass?
 
haruspex said:
Right, so has the mass defect (of the whole system) increased or decreased? What does that mean about the change in total mass?
The mass defect of the system increases so the total mass also increases. This means that Ne has higher binding energy than F so some energy must be released to keep the energy conserved?

Thanks
 
songoku said:
The mass defect of the system increases so the total mass also increases.
A defect is a shortage. If I have a shortage of cash for something I want to buy and the shortage increases, do I have more cash or less?
 
haruspex said:
A defect is a shortage. If I have a shortage of cash for something I want to buy and the shortage increases, do I have more cash or less?
Oh ok so since the shortage increases it means that mass of the product is less compared to mass of reactants so some of mass of reactants is converted to energy and released through the process
 
  • #10
songoku said:
Oh ok so since the shortage increases it means that mass of the product is less compared to mass of reactants so some of mass of reactants is converted to energy and released through the process
Yes.
 
  • #11
Thank you very much
 

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