How do hydrogen bonds affect solubility?

1 Answer

Molecules that can hydrogen bond with water have a higher solubility in water.


Molecules which are capable of hydrogen bonds have hydrogen atoms which are covalently bonded to highly electronegative elements (O, N, F). The presence of hydrogen bonding between molecules of a substance indicates that the molecules are polar. This means the molecules will be soluble in a polar solvent such as water.

Some examples of polar molecules which can hydrogen bond are ammonia (#NH_3#) and methanol (#CH_3OH#). The polarity of these molecules indicates that they will dissolve in water.

#CO_2# can form hydrogen bonds with water, but its linear shape makes it a nonpolar molecule. This means that carbon dioxide is less soluble in water than polar molecules are. The solubility of carbon dioxide is increased when the water is cold, and decreased greatly when the water is warm.

NOTE: Possibly confusing is a molecule like #O_2#, which has no bonds between O and H, but rather just a double bond between the two atoms of oxygen. It is also a linear molecule (O=O) which makes it non-polar and insoluble in water.