Why does water have a high enthalpy of vaporization?
When you vaporize a liquid, you break apart any intermolecular attractions, because while a liquid is composed of molecules closely packed, a gas is composed of separate molecules zooming around in space. To say that water has a high heat of vaporization means that it takes a lot of heat energy to change its phase from liquid to solid. The reason why is that water forms relatively strong hydrogen bonds between the molecules. Within each molecule, the oxygen atoms are far more electronegative than the hydrogen atoms, so the oxygen pulls all the electrons towards it. The oxygen in a water atom has a negative partial charge, and the hydrogens have partial positive charges. Then the positive hydrogen atoms from one water molecule strongly attract the negative oxygen atoms from another water molecule. These attractions are called ‘hydrogen bonds.’ The enthalpy of vaporization goes into breaking up these hydrogen bonds. The reason something like benzene has a low enthalpy of vaporization (i.
