[unleash10]

A while back I remember that the phase diagram of water tells us that liquid water is denser than solid water because of its downward slope for the solid/liquid line. However,I cannot remember why this is so. Can anyone remind me?

[plu]

The idea is that if you apply pressure to water as ice, it will eventually turn into liquid water.  On a phase diagram of water, if you trace a vertical line up from any temperature below the triple point, you will see that solid water eventually turns into liquid water, provided that there has been a sufficient increase in pressure.  Therefore, the liquid phase of water must be denser than the solid phase.

[Donaldson Tan]

. liquid water is denser than solid water ...

Ice floats on water, isn't it?

[mike]

Ice floats on water, isn't it?

Yes, this is true. We must therfore presume that the water molecules in ice are arrangeed in such a way that they are further apart from each other than in liquid water.

From memory I believe water is most dense at 4C.