THE CHEMISTRY OF
ACIDS, BASES AND SALTS
You must learn a littleaboutthe chemical composition and structure of acids
and bases. But it will be easier to do thisiffirst we takeanotherlook at an old
friend, H20.
As you know, water is acombinationof two kinds ofatoms-hydrogenand
oxygen. One of the hydrogen atoms in a molecule of water can act independently,
while the other onecannot;it always accompanies the oxygen atom. You are
used to seeing the formula for water written as H20.Itcan be written correctly
inanotherway, too: H-OH is exactly the same in numerical value. H-OH,
however, shows not only how many atoms of hydrogen and oxygen there are
in a molecule of water, but also how they are arranged. In other words, it
shows the chemical structure as well as the chemical composition of a molecule
of water. This is theempiricalway of writing the formula for water.
Now let's see what this empirical formula tells usaboutwater. There is no
dash between the OH. This meansthatthese two atoms are very tightly bound
together andthatif the whole water molecule breaks up, these two atoms will
still stay together. If they move toanothermolecule, they will move together as
one complete unit. Pairs or groups of molecules bound as tightly as this are
calledradicals.The OH radical is often called thehydroxylradical.
The dash after the first H showsthatit is bound to the OH radical, but not
as tightly as the 0 and H in the radical. The first H can be separated from the
radical fairly easily. If the molecule of water breaks up, the first H will go off
by itself.Itmight remain separate for a while. Or, in a new molecule, it might
joina radical again in a fairly loose union, or it might evenjoinwith an 0 to
becomepartof an OH radical itself. When separated, the two parts of the water
molecule act differently, but whenever possible they join each other to become
water.
Now how does this relate to acids and bases and the effect they have on one
another?Anacidis a substance with a hydrogenatomthatcan be easily pushed