My 11-year-old has a question. He wants to know: if you compress water under very very high pressure, will it squeeze the water molecules closer and closer together until the water turns solid? We Googled a little and it looks like the answer is No, but we don’t understand why it wouldn’t be the case.
This is a great question. Thanks.
Water freezes by virtue of water molecules hydrogen bonding into a three dimensional solid structure (Google: molecular structure of ice). This structure, uniquely, has a larger volume than the non-structured liquid water. Hence it is less dense–ice floats.
Visualize water in a cylinder with a piston pushing down on it applying increasing pressure. If water turning solid (ice) involves increasing volume, the piston pressure holding volume small will prevent that structure form forming. Hence, under increasing pressure water remains in its liquid state.
With sufficient cooling under high pressure, there will be some point at which it may turn into an amorphous non-structured solid, but offhand I don’t know what point that would be.