Water’s subtle complexity manifests itself in many ways. Unlike other liquids, it flows faster under high pressure than under low pressure. Its solid form is lighter than its liquid form. As a solvent, it is gentle enough to serve as the cradle of life yet brutal enough to carve the Grand Canyon.

This contradictory character results from an atomic arrangement that makes water’s oxygen and hydrogen atoms like to form bonds with practically anything that crosses their pass, even other water molecules.
We call adhesion the attractive force between the molecules of the liquid and another substance. Cohesion is a similar attractive force between molecules within liquid. One of the observations is the balance between the different properties of adhesion and cohesion. This balance gives the liquid its degree of “wetness”.
For example, if you push a glass tube into a beaker full of water, the water will rise up the tube- the narrower the tube, the higher it’ll rise. This is due to the adhesion between the water molecules and the glass tube is greater than the cohesion within the water itself. If the same experiment is to be carried out with mercury, the tube would cause a depression to form in the liquid. This shows that the balance between adhesion and cohesion is opposite. Also for the same reasons, in the beaker of water the edge of the liquid curves upwards along the sides, whereas in mercury it curves downwards. It is the adhesive properties of water, which cause it to be soaked up by sponges, blotting paper, etc.
Water is fairly adhesive but some other liquid shows more adhesive behaviors. Therefore, “wetness” has a different degree and with the above properties, water is considered wet.

[ top ]
[ return to normal version ]