The Basic Chemistry of Acids and Bases
A lot of chemistry requires you to understand the difference between acids and bases. An acid is a substance that donates an H+ ion to another chemical species called a base. A base is a substance that accepts (combines with) an H+ ion.
If you need to know the concentration of the H+ ion in solution, you can do so by representing the H+ molarity, [H+]. Another way to represent the H+ concentration is the pH, which is the negative logarithm of the H+ molarity. The following equation shows this mathematical relationship as well as the way to calculate the H+ molarity given the pH:
pH = –log[H+]; [H+] = 10–pH
pH = 7 is neutral.
pH less than 7 is acidic.
pH greater than 7 is basic.