Does the volume of water increase after heating?

Answer 1

The volume of water can be affected both positively and negatively depending on weather conditions. The two factors to take into account here are atmospheric pressure (which causes a negligable change in volume for liquids - pressure only really needs to be considered when dealing with gasses) and more signifigantly temperature. Water is most dense at temperatures just above 0 Celsius (or 273 Kelvin). Temperatures above this will cause the water molecules to move more quickly, causing the volume to increase. The reason why ice is less dense that cold water (when the previous reason suggest it should be denser) is because of hydrogen bonding. The hydrogen atoms of one water molecule interact with the oxygen of another. Because of these intermolecular interactions, water molecules can be more closely 'packed' together when they are free to move around in liquid phase; the solidification of water into ice causes the molecules to be arranged in a rigid structure, leaving 'gaps'. Hope this helps!