Why does kinetic energy not change when ice melts to water at 0°C?

[titansarus]

Hi.
In all of my question, I mean degrees celsius when I say degree.
Think we have a 0 degree ice. we give some energy to it (by a heater) and all of it get into a 0 degree water.
How does the kinetic and potential energy of the molecules change?

In the book in which I saw this question, it said that potential energy increases and kinetic energy of molecules doesn't change because of K= 3/2 k T. My problem is that we use K = 3/2 k T in ideal gases. is it valid for liquids or solids? Is it right to say that the mean kinetic energy of a solid and a liquid (of the same material and the same mass) is constant in temperature Θ? It doesn't seem logical. If it is true, how the water is more fluid and free than a solid?

Whatever the answer is, is it same for liquid and gas?

Sorry for my English.

 

[BvU]

Hello titan,

we use K = 3/2 k T in ideal gases

meaning gases of infinitely small hard spheres that stilll can collide (I realize this is contradictory). So not for liquids and not for solids.

 

[titansarus]

Hello titan,

meaning gases of infinitely small hard spheres that stilll can collide (I realize this is contradictory). So not for liquids and not for solids.

So, This means that if we have a liquid and a solid of the same temperature, we can't say their molecules (or particles) have the same kinetic energy. and the liquid particles has more kinetic energy than the solid of the same temperature, Is this right?

 

[BvU]

Good question. The constituents (ions, atoms, molecules) of a solid can't wander about, but they can vibrate about an average position. The energies associated with those degrees of freedom are generally less than the energy these constituents have when in the liquid state -- hence the latent heat of melting.

Perhaps you notice I'm treading carefully here -- some expert input would be welcome