Energy of water?

  • #1

Main Question or Discussion Point

Seems to me there are 3 sources of energy released when water freezes:

Release of heat to lower from whatever temp you start with to 0°C, latent heat released in the transition to from water at 0 to ice at 0, and the expansion energy released as the water increases in volume during the phase change. I sort of no how to calculate the first two bits, but not sure how to quantify the expansion energy.
 

Answers and Replies

  • #2
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The expansion energy depends on the pressure in the medium that surrounds the ice.
It's equal to p ΔV, where p is the pressure and ΔV the change in volume.

In a vacuum it would be 0.

for 1 kg of ice under atmospheric pressure, p is about 10^5 N/m^2 and ΔV is 10^-4 m^3,
so the expansion energy is about 10J.
 
  • #3
1,948
200
The expansion energy is already included in the latent heat which is usually tabulated as latent heat at constant pressure (and so is the specific heat)
 

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