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Originally posted by Seed76
reply to post by davespanners
Yes indeed. It´s fascinating the amount of force that is produced by the expansion of water has when it freezes.
The specific heat capacity of water is 4200 J/KG/C. That is, it takes 4200 Joules to raise the temperature of 1Kg of water by 1 degree Celsius.
Conversely, the water must lose 4200 Joules of energy to cause a drop in temperature of 1 degree in 1Kg of water.
When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%
This unusual behavior has its origin in the structure of the water molecule. There is a strong tendency to form a network of hydrogen bonds, where each hydrogen atom is in a line between two oxygen atoms. This hydrogen bonding tendency gets stronger as the temperature gets lower (because there is less thermal energy to shake the hydrogen bonds out of position).
Originally posted by -PLB-
reply to post by jlafleur02
Ok that is new to me, I was unaware that theory had been replaced, so thanks for the update. I think the point that the energy required to burst the pipes comes from the thermal energy contained in the water still holds. As the pressure goes up, the temperature goes down, so you have perfect conservation of energy.edit on 31-12-2010 by -PLB- because: (no reason given)
Originally posted by jlafleur02
so if it is thermal energy then with the absence of the force of pressure being shown we should see thermal energy or heat being released that would equal the energy of pressure if the water was in a contained system. I would say this is a mechanical energy that is cause by the interaction of the molecules.
I would also say that ice is the natural state of water and adding energy to it disrupts this state.
Originally posted by jlafleur02
I think we need to calculate the amount of force that water will exert, the amount of heat lost during the freezing phase, and the amount of heat that is needed to thaw the ice.
convert all measurements to a common unit do some math then go from there. I am no mathematican, can't even spell it right.
Any numbers guys out there?
Originally posted by 4nsicphd
There are about 12 gallons of water in a 10 foot long 3/4 inch water pipe so about 4000 kilojoules of heat is given up to the surroundings when that water freezes. The heat isn't "lost." It is transferred to the pipe and whatever is around the pipe.
Again, this idea is entirely wrong. Want proof? Do you keep your water taps on to prevent this buildup of pressure? No. So anytime your water tap is off, you are blocking the water. I can tell you, the breakage happens where the ice has formed and needs to expand. not in the liquid water.
Originally posted by Optix
being captain obvious here.... pipes bursting in the winter is from the pressure of water behind the ice blockage that keeps building up (17-20psi) and the contraction of the steel in the pipe making it smaller.
Now freezing water in a sealed bottle doesn't the air have to move somewhere? also the contraction of the bottle itself.