# Increasing the Melting Point via Pressure Increase

1. Nov 3, 2008

### N8

1. What is the pressure needed to increase the melting temperature by 20 centigrade degrees?

Given: Molar Volume (solid) at normal melting temp is 18.92 cm^3
Given: Molar Volume (liquid) at normal melting temp is 19.47 cm^3

2. Relevant equations

delta H (s>l) = T(melting point)* delta S(s>l)

3. The attempt at a solution

Not sure how I can even come up with an equation. I know I can calculate the change in volume with the molar volumes. The equation listed doesn't seem to help any either, anyone have an equation that works?

dP/dT = L/TdeltaV can't be used since I dont know latent heat...

2. Nov 3, 2008

### Mapes

Look into the Clapeyron relation. An increase in pressure energetically favors the denser phase (solid) and therefore increases the melting temperature.

3. Nov 3, 2008

### N8

Well I dont know the latent heat energy (it can be found, but the book is suggesting you can solve the problem without it, and without the actual melting point but simply knowing the change in melting point)

4. Nov 3, 2008

### Mapes

The problem can also be solved if you know the molar or specific entropy of the solid and the liquid.