Calculating the Freezing Point of Mercury Under Pressure

In summary, the conversation discusses the calculation of the temperature at which the bottom of a column of mercury will freeze, given its density, enthalpy of fusion, and change in molar volume. The first equation is used to calculate the pressure in the column, and the second equation is used to solve for the freezing temperature. The calculated answer of 234.2 K is questioned, as it seems lower than expected. The slope of the melting point line and the comparison to water's change in temperature at different pressures are also mentioned. The use of the correct equation is confirmed.
  • #1
winterwind
29
0

Homework Statement


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?


Homework Equations



p = [tex]\rho[/tex]gh

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


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!
 
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  • #2
winterwind said:
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?
What's the slope of the m.p. line? Positive? Or, negative?
winterwind said:
I would expect it changes more than 0.1 K anyways.
Water changes 0.01 K/atm, and has which slope?
winterwind said:
Am I using the correct equation?
Yes.
 

What is the freezing point of mercury?

The freezing point of mercury is -38.83°C or -37.89°F.

Why does mercury have such a low freezing point?

Mercury has a low freezing point because it is a metal with weak metallic bonds, making it a liquid at room temperature.

Is the freezing point of mercury affected by pressure?

Yes, the freezing point of mercury is affected by pressure. As pressure increases, the freezing point of mercury also increases.

What is the significance of knowing the freezing point of mercury?

Knowing the freezing point of mercury is important in various industrial and scientific applications, such as thermometers, barometers, and dental amalgams.

Can mercury freeze at room temperature?

No, mercury cannot freeze at room temperature as it has a freezing point of -38.83°C, which is much lower than room temperature.

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