Where does the heat come from when a liquid freezes?

[pivoxa15]

Homework Statement

When a liquid freezes, it gives out heat. Where does this heat come from?

Homework Equations

none

The Attempt at a Solution

Does this only apply to water or other chemical substances as well.

The heat comes from the strong bonding when as a liquid. But now this kind of potential energy stored in the bonds is released into kinetic energy hence heat outflow. This explanation is only for water as the liquid state has stronger bonding hence higher potential energy in the liquid bonds. But what about other chemical substances?

 

[Astronuc]

To change state from solid to liquid, one must 'add' heat. To change state from liquid to solid, one must 'remove' heat.

Latent is the term applied to the energy.
http://www.physchem.co.za/Heat/Latent.htm

http://en.wikipedia.org/wiki/Latent_heat

See also - http://hyperphysics.phy-astr.gsu.edu/hbase/class/phscilab/heati.html
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase2.html#c1

 

[pivoxa15]

At a molecular level, why is heat released when liquid is turned into solid? People usually explain it in terms of when solid is turned into liquid, heat is added. I want to know the other way around. Is it because there use to be a bit of kinetic energy in the molecules when in liquid state but after it has changed into a solid, this kinetic energy is lost. It can't disappear and we measure a decrease in temperture of the substance so heat must be released. We can also measure an increase in the temperture of the surrounding environment if the temperture is at or colder than the melting pt of the substance?