# Thermodynamics- microstudy

1. Jun 28, 2012

### dhinesht

Dear all,
Generally as per physics the atom has nucleus over that electrons are spinning. I could n't imaging basic thermal terms with this physics. please clarify me. If i am wrong correct me.

1) i am confusing the term internal energy with electron spin. Is any relation there?

2) we defining enthalpy as useful energy(i.e. internal plus external pressure energy) and the entropy as dispersed energy and it cannot be used. What actually differs this two with respect to electron motion.?

3) Thermal conductivity of a material is based on the electron interaction. Electric conductivity also based on the same. But both are not proportional for all materials. Why?

4) We are telling the linear, rotational, vibration kinetic energies and potential energy of a molecule is increasing when doing heating, Is it a molecular phenomena or atomic phenomena? what is happening while adding latent heat then?

5) boiling point is depend on pressure. i.e. we restrict the molecular movement by applying external pressure so need more energy to overcome it, but the latent heat is less needed for high pressure medium to change its phase. Why?

2. Jun 28, 2012

### Simon Bridge

I don't think we'd normally use thermal terms for a single atom. But you will see the Fermi (electron or hole) gas in solids treated thermodynamically ... or, at least, thermodynamic properties of a solid being worked out from electron states.

With that in mind - and pointing briefly in useful directions rather than showing you definitive answers:

1. electron spin adds another degree of freedom to the state.
2. entropy is usually related to the density of states - more closely related to ideas like information and order/disorder
3. because they are different interactions - electrical conductivity relates to ordered motion and depends on band structure in a solid while thermal conductivity relates to random motion.
4. molecular phenomena - with latent heat, the state is changing so inter-molecular attractions are dissolving. Note: a molecule can be a single atom ... but when a solid crystal (say) changes state the liquid is not usually mono-atomic. Or maybe you are thinking of the state-change to a plasma? Plasma's are different.
5. Difference between temperature and energy.

Looks like you need a text on statistical mechanics of solids, liquids, and gasses.
Recall - none of these answers are intended to be complete: they are indicative only. Have a think about them, do more reading, then get back to us.

Also I know there are a few others who will want to be more specific so I don't expect to have to :)

3. Jun 29, 2012

### Studiot

Welcone to Physics Forums.

Simon's advice is good, your subject is too vast to cover in one go in the forums so you will need to read a bit, chew it over, and ask more questions - lot's of them.

One point to clear up.

Entropy and Energy are different. You should know or find out quickly before embarking on statistical mechanics the dimensions (units) of both.

An area on a pressure-volume diagram measures energy as does an area on an entropy-temperature diagram. You would not call pressure or volume energy.

Look up 'indicator diagrams'.