Home » Ask & Discuss » Physics. » Thermal Physics « Back to Discussion

Thermal Physics

New kid on the Block

Joined:	27 Jun 2011
Post:	3

27 Jun 2011 10:18:39 IST

0 People liked this

339

what is the difference between internal energy and enthalpy of a system in thermodynamics?

None

what is the difference between internal energy and enthalpy of a system in thermodynamics?

Share this article on:

Comments (2)

Karan Bulani

New kid on the Block

Joined: 5 Jun 2011

Posts: 11

1 Jul 2011 08:34:13 IST

Like 0 people liked this

internal energy is the energy that is there inside the system and comprises of P.E. and various forms of K.E.

Enthalpy of the system is the total heat content of the system at that time at constant pressure.

edison

Forum Expert

Joined: 19 Oct 2006

Posts: 7537

30 Nov 2011 17:54:46 IST

Like 0 people liked this

Difference between enthalpy and internal energy

Chemists routinely use H as the energy of the system, but the pV term is not stored in the system, but rather in the surroundings, such as the atmosphere. When a system, for example, n moles of a gas of volume V at pressure P and temperature T, is created or brought to its present state from absolute zero, energy must be supplied equal to its internal energy U plus pV, where pV is the work done in pushing against the ambient (atmospheric) pressure. This additional energy is, therefore, stored in the surroundings and can be recovered when the system collapses back to its initial state. In basic chemistry scientists are typically interested in experiments conducted at atmospheric pressure, and for reaction energy calculations they care about the total energy in such conditions, and therefore typically need to use H. In basic physics and thermodynamics it may be more interesting to study the internal properties of the system and therefore the internal energy is used.

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team