Ice and Expansion

[Nitack]

When water freezes it expands. This expansion can be quite impressive and even apply a great deal of force if the ice is in a sealed container. We have all had a coke can explode in the freezer. :singer:

 

Question: If water expands when it freezes (enough energy is taken out of the substance that it becomes a solid, and we can quite easily see the potential of that force, where does that energy come from? I ask because I understand the laws of thermodynamics (at least to an extent), and understand that you can never get something for nothing in terms of energy. But the energy and force that ice is able to exert has to come from some where. It is not chemical energy, because the water is not chemically changed at all to release that energy. I am not even sure it is potential energy from the initial heating up of water. You can add enough energy to solid water to melt it and take out exactly the same amount of energy to freeze it again, and you have the same amount of energy put in but still able to extract energy from the expansion of the freezing.

 

So perhaps there is a really simple explanation, but I am missing it. And I would hate to think that a substance as common as water could violate the laws of thermodynamics.

[Jimoin]

I think you are thinking about this backwards.

 

If you compress Ice enough (i.e. put energy into the system) it turns into water, regardless of it's temperature.

 

Usually the container isn't exerting enough force to stop the contained water expanding (transforming into crystals) through loss of energy.

 

I probably should have waited for someone to explain that better than I, and I'm sure they will, but I need my 10 posts~ :)

[buddyzen]

honestly yes i think there is a simple answer to this question but i am not sure if mine is right

 

 

Temperature arises from the random submicroscopic vibrations of the particle constituents of matter. These motions comprise the kinetic energy in a substance. More specifically, the thermodynamic temperature of any bulk quantity of matter is the measure of the average kinetic energy of a certain kind of vibrational motion of its constituent particles called translational motions. Translational motions are ordinary, whole-body movements in three-dimensional space whereby particles move about and exchange energy in collisions. Fig. 1 at right shows translational motion in gases; Fig. 4 below shows translational motion in solids. Thermodynamic temperature’s null point, absolute zero, is the temperature at which the particle constituents of matter are as close as possible to complete rest; that is, they have minimal motion, retaining only quantum mechanical motion.[1] Zero kinetic energy remains in a substance at absolute zero (see Heat energy at absolute zero, below).

 

 

 

At its simplest, “temperature” arises from the kinetic energy of the vibrational motions of matter’s particle constituents (molecules, atoms, and subatomic particles). The full variety of these kinetic motions contribute to the total heat energy in a substance. The relationship of kinetic energy, mass, and velocity is given by the formula Ek = 1⁄2m • v 2.[13] Accordingly, particles with one unit of mass moving at one unit of velocity have precisely the same kinetic energy—and precisely the same temperature—as those with four times the mass but half the velocity.

 

 

 

The total kinetic energy of all particle motion—including that of conduction electrons—plus the potential energy of phase changes, plus zero-point energy[1] comprise the internal energy of a substance, which is its total heat energy. The term internal energy mustn’t be confused with internal degrees of freedom. Whereas the internal degrees of freedom of molecules refers to one particular place where kinetic energy is bound, the internal energy of a substance comprises all forms of heat energy.

 

 

 

so basicly if i am understanding this right it converts its heat energy to expand but of course i could be totally wrong because when it melts doesn't it get more heat energy?

 

well i tried lol maybe this will help a bit