How does the density of water vary according to temperature, and its physical state?

2 Answers
Jul 15, 2017, but give Tyler a break........


Of course the density of steam is FAR less than the density of water. As a liquid, #rho_"water"# varies SLIGHTLY with temperature. The maximum density of water normal conditions occurs at #4# #""^@C#. To a first approximation we quote the density of water as #1*g*cm^-3#......this is usually good enuff for most calculations.........

That ice is LESS dense than liquid water, and as a result icebergs floats, is a highly unusual property. Most liquids are LESS dense than their solid phases - water is one exception.

Jul 15, 2017

Technically, the mass of water in grams is numerically the same as the volume in millilitres only at 4 °C.


However, the difference is so small that the numbers are almost the same.

The problem is that water expands as it warms from 4 °C.

Thus, if you had 500 mL of water at 4 °C and it warmed to 20 °C, its new volume would be 501 mL.

That's why volumetric glassware is calibrated to hold a given volume at a specific temperature, usually 20 °C.

If you had 500.0 mL of water at 20 °C and the water temperature warmed to 25 °C, the new volume would be 500.5 mL.

You could certainly see the difference at the graduation mark but, even so, the error is only 0.1 %.

The difference is important for extremely precise work.

However, in an undergraduate lab, it is usually acceptable to make the approximation that the mass and volume of water are numerically the same.