# Freezing point of mercury

1. Oct 10, 2009

### winterwind

1. The problem statement, all variables and given/known data
The enthalpy of fusion of mercury is 2.292 kJ/mol, and its normal freezing point is 234.3 K with a change in molar volume of +0.517 cm/mol on melting. At what temperature will the bottom of a column of mercury (density 13.6 g /cm3) of height 10.0 m be expected to freeze?

2. Relevant equations

p = $$\rho$$gh

p = p* + [($$\Delta$$fusH)$$/$$(T*$$\Delta$$fusV)]/(T - T*)

3. The attempt at a solution

I calculated the pressure in the column of mercury using the first equation provided above. I then solved the second equation for T, plugged in the given values, with p*= 101 kPa and T* = 234.3 K (the normal pressure and boiling point).

I get an answer of 234.2 K, which doesn't make sense, since when you raise the pressure, shouldn't you get a higher temperature freezing/melting point? I would expect it changes more than 0.1 K anyways.

Am I using the correct equation?

Thanks!

Last edited: Oct 10, 2009
2. Nov 26, 2016

### Bystander

What's the slope of the m.p. line? Positive? Or, negative?
Water changes 0.01 K/atm, and has which slope?
Yes.