It is a well known fact that water expands when it freezes, and here's one of the explanations I found on Physics SE:
"The expansion upon freezing comes from the fact that water crystallizes into an open hexagonal form. This hexagonal lattice contains more space than the liquid state."
(1) According to what I've read earlier, water expands on freezing due to hydrogen bonding (the molecules exist in a cage like structure, whose breakage results in increase in volume) Could someone please explain how the two explanations are related?
I've read Solid State, Thermodynamics etc. so I'm looking for the best possible and detailed explanation possible.
(2) Can we define a coefficient of volume expansion for this freezing process? If yes, how? Would it be an experimentally determined constant (or variable quantity) or is it possible to obtain it as a function of temperature, number of molecules, etc. (related quantities)