Calculate melting point of ice under pressure

AI Thread Summary
To calculate the melting point of ice under a pressure of 6000 kPa, the Clausius–Clapeyron relation is relevant, but the focus should be on using the densities of solid and liquid water to determine the volume change. The discussion highlights confusion regarding the correct application of equations, specifically distinguishing between those for melting and evaporation. Participants suggest using the densities to calculate the volume change and rearranging the equations to find the change in temperature (delta T). Ultimately, the melting point can be adjusted based on the calculated delta T. Understanding the heat of fusion and its role in the calculations is also emphasized.
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Homework Statement


The density of solid water is approximately 920 kg m^-3 and that of liquid water is 1000 kg m^-3. Calculate the melting point of ice under a pressure of 6000 kPa.


Homework Equations



This is my problem. How do I approach this? I don't see any relevant equations in my textbook.


The Attempt at a Solution


See 2.
 
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Clausius–Clapeyron relation perhaps?
 
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Borek said:
Clausius–Clapeyron relation perhaps?

Not really. That has to do with pressure, but how does the density fit in?
 
Use it to calculate volume change.
 
Last edited by a moderator:
Borek said:
Use it to calculate volume change.

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I'm not following. Use the density to calculate volume change? Or use the Calpeyron equation to calcululate it? The equation I have found so far is:

delta(ln p) = delta_vapH/RT^2 * delta T

Is this correct? Thanks
 
No, this is version for evaporation, you need version for melting. Use given densities to calculate volume change.

See wikipedia article on Clausius–Clapeyron relation.
 
Borek said:
No, this is version for evaporation, you need version for melting. Use given densities to calculate volume change.

See wikipedia article on Clausius–Clapeyron relation.

So, like their example at the bottom of the page...

7ccf0e9ffa7dc258672182cdaa1060e4.png


and then rearrange and solve for deltaT and I get -0.4438K which doesn't mke much sense?
 
What is delta T?
 
Borek said:
What is delta T?

Change in temperature (melting temp).
 
  • #10
And what was delta T you calculated?
 
  • #11
Borek said:
And what was delta T you calculated?

Ok, so it would be: melting point water - (-0.4438K) for a final melting point?
 
  • #12
That would sound logical.
 
  • #13
Borek said:
That would sound logical.

Awesome! Thanks, I appreciate the help!
 
  • #14
i have something like it:

The densities of ice and liquid water at 1atm (101,325KPa) and 0oC are
917Kg/m3 and 999,8Kg/m3, respectively. The heat of fusion of water is 334720J/Kg.
Calculate the melting point of ice at 0,5atm (50,662KPa) and 101atm (10,2338MPa).

i don't know how i find "delta"H
 
  • #15
What IS delta H?
 
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