Water is a very strong solvent and often referred to as the universal solvent. A solvent is a liquid or gas that dissolves another substance resulting in a solution. Substances that dissolve in water, like salts, sugars, acids, and alkali are called hydrophilic (water-loving) while those that do not mix well with water, like grease or oil, are called hydrophobic (water-fearing).
Water is, of course, the substance created when two molecules of hydrogen form a chemical bond with one molecule of oxygen â€“ commonly abbreviated as H2O. Water is a polar molecule. The oxygen has a negative charge while the hydrogen has a positive charge giving the water molecule a strong dipole structure â€“ like a magnet with it’s north and south (positive and negative) poles. And just like a magnet’s poles, a water molecule’s poles are attracted to the opposite charge in other water molecules. This weak interaction causes both water’s cohesive property and adhesion property and is responsible for the high surface tension of water. If you’ve seen water bead up on a surface you’ve seen surface tension. This tension also exhibits another of water’s properties and that is capillary action â€“ or the tendency of water to move upward in a tube against the force of gravity.
Unlike a bar magnet with a single positive and single negative pole the water molecule has two positive poles (the hydrogen atoms) and one negative pole (the oxygen atom) so a U shaped magnet with the bend of the U being the negative pole is a better model. Because magnetic poles attract the opposite charge, if you had 100 water molecules, the negative poles (the oxygen atoms) would be attracted to one of the negative poles (a hydrogen atom) of one of the other 99 water molecules. What about the second hydrogen atom on each of the molecules? They attract other negatively charged molecules. Guess what has a negative charge? Dirt.
Have you ever wondered why fine particles of dirt settle on all the surfaces in your home? Yes, dust is just fine airborne particles of dirt. Well, our planet is constantly bombarded by waves of energy that we can’t see. Besides the UV (ultraviolet) rays that cause sunburn, there are longer wave lengths of energy called Gamma Rays. Unlike UV rays, however, which can be blocked by materials (like a hat) or chemicals (like a sunblock lotion), gamma rays go right through everything â€“ including us. When the gamma rays pass through objects they knock electrons out of the atoms the object is made of. And when atoms lose electrons they become slightly positively charged. Since this occurs constantly, most objects in our homes have an overall positive charge. Along comes a breeze that disperses some fine dirt particles in the air that are negatively charged and â€“ you guessed it â€“ the negatively charged dust is attracted to the positively charged surfaces and sticks there.
So let’s imagine a dirty surface, a counter-top for instance, and think what would happen when we spread some water on the counter. Firstly, the â€œextraâ€ positive poles (hydrogen atoms) would be repelled by the slight positive charge of the counter-top so that the water molecules would be positioned like a U with both positive poles upward and the negative pole downward. The dirt particles on the counter-top, because they have a slight negative charge would be attracted to the â€œextraâ€ positive poles at the â€œtopâ€ of the water. The dirt particles have now be separated from the surface of the counter and in effect are being held in suspension by the water. Now we simply wipe away the water and the dirt in solution right along with it. In my humble opinion, water certainly deserves the moniker of universal solvent.