density of ice is lower, as explained above. Also the strong increase of the
viscosity of water at decreasing temperature, despite the decrease in density,
is uncommon. So is the strong increase incpat low temperatures. All these
phenomena have to do with the particularities of hydrogen bonding, but we
will not go further into possible explanations.
The anomalies have some important consequences. The expansion of
the system due to ice formation can cause high pressures. Nearly everybody
knows about the bursting of water pipes that become frozen. Some
FIGURE15.13 Some properties of ice and (undercooled) water as a function of
temperature. Given are mass densityr, viscosityZ, and specific heat at constant
pressurecp, all at atmospheric pressure.