has the highest heat of vaporization per gram of any known liquid.
A comparison of water with a few other common liquids is given below.
The reason for the specially high value for water is the network
of hydrogen bonds that holds the water molecules together, even
in the liquid state.
In the "iceberg" or "flickering cluster" picture of liquid water
structure, small clusters of water molecules are held together by
hydrogen bonds in a more or less icelike manner (right). Bonds are
made and broken continually, and one particular molecule may be
bonded to others at one instant and free the next.
Throughout the liquid a certain percentage of the possible hydrogen
bonds will be formed at a given moment. These bonds must be broken
when the liquid is vaporized, and this requires energy. The result
is a higher heat of vaporization than for liquids without hydrogen