# Homework Help: Say there is a vessel with constant volume

1. Nov 9, 2013

### GGdog0818

Say there is a vessel with constant volume. We know the EOS, moles and Cp of the vapor in it. How can we design an experiment to measure the (dS/dP) at constant V?

I think the idea is to transform (dS/dP)v into something that consists of Cp, V,P,T only. Then we can measure the small difference in T or P to substitute into equation and get (dS/dP)v.

But how? Anyone has an opinion?

THX
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Nov 9, 2013

### Simon Bridge

Welcome to PF;
Directly: dS/dP is the slope of the S vs P graph isn't it?

Well, you could find a way to vary the pressure and measure the entropy - plot S vs P and take the slope.
How you do that, and cope with the complications, determines the experiment.

3. Nov 9, 2013

### Staff: Mentor

Start with the equation for dH expressed in terms of dT and dP, and set this equal to TdS + VdP. Then eliminate VdP from both sides, and you will see what to do next.