# Constraints on the Gibbs Equation, Tds = dh - vdP

afurry91

## Homework Statement

What constraints are imposed on the use of the Gibbs equation Tds = dh - vdP

Tds = dh - vdP

## The Attempt at a Solution

I seem to be stuck on this question. So far I have come up with the following constraints, but I'm not even sure if they are correct:

1. The equation holds for only closed systems at constant pressure
2. The equations holds only for systems in which the free energy depends only on P and T.
3. The equation doesn't apply on mixtures or supercooled liquids.

Homework Helper
Gold Member

## Homework Statement

What constraints are imposed on the use of the Gibbs equation Tds = dh - vdP

Tds = dh - vdP

## The Attempt at a Solution

I seem to be stuck on this question. So far I have come up with the following constraints, but I'm not even sure if they are correct:

1. The equation holds for only closed systems at constant pressure
2. The equations holds only for systems in which the free energy depends only on P and T.
3. The equation doesn't apply on mixtures or supercooled liquids.

#1 can't be right - there is dp in the formula ...
#2 ?
#3 ?

So: 1st hint: how does the term Tds enter your equation?