Re: Does water under pressure break the one of the laws about heat disbursal?

You may have a partly mistaken idea about what water does (or maybe it is just the way you are wording things). It is not true that water "will not go below 4 degrees."

As you say, 4 degrees Celsius (actually about 3.98) is the temperature of maximum density at atmospheric pressure. At other pressures, the maximum occurs at a somewhat different temperature (for example, at 100 bars it is about 2 degrees C). But you can cool it further below that density maximum; it will just expand a little. Then when you get to the freezing point it will expand a lot.

It sounds like you are maybe thinking of a situation in which you have set the density of the water at a fixed amount by putting it in a sealed container. In that case, the laws of thermodynamics will still work and heat will flow from the water to the freezer and the temperature of the water will go down. At this point, the water will be trying to expand, and one of two things will happen:

1) The container will expand or rupture due to the expansion of the water. Incidentally, this process is a major cause of wear and tear on roads -- water gets into cracks and then freezes with the resulting expansion widening the crack. Some weathering of rocks works the same way.

2) If the container is sufficiently strong, the pressure will go up so that the liquid stays compressed to the original density. For example, let's say you start with liquid water at its density maximum at atmospheric pressure which is about 3.98 degrees C, with a density of 999.975 kg/m3. Let's say you cool it to 1 degree C. The resulting pressure will be that given by water at 1 degree C and 999.975 kg/m3 density, which turns out to be just 2.46 bars (remember that 1.01325 bars = one atmosphere). So you really don't get much added pressure from simply cooling liquid water because the density maximum is so weak (in my example, at 1 degree C, the density of water at atmospheric pressure is 999.902, so it doesn't take much pressure to compress it to 999.975). The big difference comes if you freeze it, because ice is about 10% less dense than liquid water (compared to the tiny fractions of a percent you get from cooling liquid water below its maximum).

If you do freeze the water, then the above two considerations also apply. And in the case of a super-strong container which allowed the pressure to increase a lot, you are correct in saying that you would get to a different form of ice. In other words, at high pressures, you can make forms of ice where the hydrogen bonding network is crushed and the ice is more dense than liquid water.

By the way, all my calculations of liquid water properties were performed using the international standards for water properties described at http://www.iapws.org.

Allan Harvey "Don't blame the government for what I say, or vice-versa."