# Latent Heat (enthalpy) of Fusion changes with Pressure?

1. Mar 8, 2012

### Hypatio

If the melting point depends on the pressure, does the latent heat of fusion also depend on the pressure? The equation relating the entropy of fusion to the enthalpy of fusion is given by:

$$\Delta H=T\Delta S$$

where T is, apparently, the temperature of melting. So, if the melting point increases with pressure, then as isentropic melting occurs the latent heat (enthalpy) of fusion decreases linearly?

2. Mar 9, 2012

### DrDu

What do you mean with isentropic melting? Usually one considers melting at fixed temperature, i.e. isothermal melting.

Generally
$dH=C_p dT +(V-T \frac{\partial V}{\partial T}|_p}dp$
with the last term in the brackets defines the isobaric thermal expansion coefficient.
Just integrate along the phase boundary $T_\mathrm{melt}(p)$ for the two phases in equilibrium.

3. Aug 1, 2012

### mattkunq

Hello Sir,
Latent heat of anything can simply be calculated by taking the difference between enthalpy after and before.

I dont' remember but the dependence of the enthalpy before and after will tell you if it will change the latent heat.