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Energy of water? 
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#1
Sep1213, 08:40 PM

P: 1

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. 


#2
Sep1213, 09:08 PM

P: 1,397

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
Sep1313, 08:01 AM

Thanks
P: 1,948

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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