Stability of Products: Nuclear binding energy vs Enthalpy


by physickkksss
Tags: binding, energy, enthalpy, nuclear, products, stability
physickkksss
physickkksss is offline
#1
Jul20-11, 05:37 PM
P: 28
I want to get my head around this....

Why is that in nuclear fusion, the formed nucleus is more stable because its nuclear binding energy/nucleon is HIGHER than the sum of its reactants

But

in general chemical reactions products are more stable if their enthalpy is LOWER than the sum of their reactants


I know that in both cases: bonds are formed, the products are more stable, and energy is released...so it has something to do with the definitions of what is +ve and -ve

But I'm trying to connect the dots here, and would appreciate any help :)

Thanks!
Phys.Org News Partner Physics news on Phys.org
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Mapping the road to quantum gravity
Chameleon crystals could enable active camouflage (w/ video)
Drakkith
Drakkith is online now
#2
Jul20-11, 06:07 PM
PF Gold
Drakkith's Avatar
P: 11,057
Binding energy refers to the energy needed to pull the nucleus apart. It is the inverse of Enthalpy which is a measure of the total energy of something. The higher the binding energy of a nucleus, the less energy it contains compared to its parts before fusion, as it released more energy during binding.
physickkksss
physickkksss is offline
#3
Jul20-11, 10:42 PM
P: 28
Quote Quote by Drakkith View Post
Binding energy refers to the energy needed to pull the nucleus apart. It is the inverse of Enthalpy which is a measure of the total energy of something. The higher the binding energy of a nucleus, the less energy it contains compared to its parts before fusion, as it released more energy during binding.
I think i get it know...the bolded part is the key.

Binding energy is actually equivalent to what we would call 'bond strength' in general chemical species.


What is the equivalent of enthalpy for a nucleus though? Can we say more stable (higher binding energy) nucleus has lower 'nuclear enthalpy' too?

Drakkith
Drakkith is online now
#4
Jul20-11, 10:45 PM
PF Gold
Drakkith's Avatar
P: 11,057

Stability of Products: Nuclear binding energy vs Enthalpy


I would say yes. The mass of an atom of Deuterium is LESS than a proton, neutron, and electron combined when they are free.
physickkksss
physickkksss is offline
#5
Jul21-11, 05:13 AM
P: 28
Can you say less mass would imply less enthalpy?
Drakkith
Drakkith is online now
#6
Jul21-11, 04:34 PM
PF Gold
Drakkith's Avatar
P: 11,057
Quote Quote by physickkksss View Post
Can you say less mass would imply less enthalpy?
Only in the right context. Deuterium has much less mass than Iron, but it is able to give off energy when it is fused, while Iron does not. So it just depends on what you are comparing and how.
physickkksss
physickkksss is offline
#7
Jul21-11, 10:42 PM
P: 28
cool....thanks for the replies


Register to reply

Related Discussions
What has bandgap gotta do with binding energy and stability? Atomic, Solid State, Comp. Physics 2
Nuclear Binding Energy General Physics 3
Binding Energy & Nuclear Reactions Introductory Physics Homework 9
Question about Nuclear Binding energy and stability Advanced Physics Homework 3