# The Naked Scientists Forum

### Author Topic: understanding enthalpy in mathematical terms  (Read 3312 times)

#### biomed0101

• Jr. Member
• Posts: 18
##### understanding enthalpy in mathematical terms
« on: 04/09/2005 09:58:34 »
I have been tackling this subject over and over, but I canīt seem to picture this in my mind.

My textbook explains the change of enthalpy as the transfer of heat in a chemical reaction, exothermic if heat is released , endothermic if heat is absorbed (this I understood), and provides me with the statement that H is E + P*V

If H = E + P*V, then H = E + (n*R*T)?

Can energy be explained as n*R*T?

Can anyone help me with this?

#### Simmer

• Sr. Member
• Posts: 229
##### Re: understanding enthalpy in mathematical terms
« Reply #1 on: 05/09/2005 20:05:59 »
Look's like no one's too keen to get involved in physical chemistry (and who can blame them! )

If I understand your question correctly, you want to know whether you can define the internal energy of the system in terms of temperature and the gas constant?  I think the answer is no, because the internal energy of the system includes potential energy as well as kinetic.

#### David Sparkman

• Sr. Member
• Posts: 234
##### Re: understanding enthalpy in mathematical terms
« Reply #2 on: 06/09/2005 01:38:42 »
Well I was the smartest guy in PChem for the two semesters it took me to pass the course, and it was almost 3 semesters for that one course but the main professor took a sabatical (rather than be fired) hehe.

the PV term is potential energy, but it is relative to the PV it is moving to. To release all the potential energy, volume would have to be infininte.

David

#### simeonie

• Sr. Member
• Posts: 351
##### Re: understanding enthalpy in mathematical terms
« Reply #3 on: 06/09/2005 09:09:11 »
oookkkk well this is way to advanced for me because I am only doing G.C.S.E maths atm.

But if energy was E then E= H-(n*R*T)

I am probably answering the wrong question and making a total fool of myself because it is probably wrong.

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#### The Naked Scientists Forum

##### Re: understanding enthalpy in mathematical terms
« Reply #3 on: 06/09/2005 09:09:11 »