Unit 8: Acids and Bases

The general population has a vague idea of what an acid is; this is the same case for bases, albeit the idea for bases is a little less common. Personally, as a child, whenever I had heard the word “acidic” I immediately thought of a lemon. Now the case is a little different; I actually think of the chemical definition when I hear the word because organic chemistry took away my childhood innocence.

There are two main schools of thought for what should be the definitions for acids and bases. The Arrhenius definition of an acid is any compound that increases the concentration of hydrogen ions ([H+]) in a solution, while the Arrhenius definition of a base is any compound that increases the concentration of hydroxide ions ([OH-]) in solution. Essentially, the Arrhenius definition of an acid/base is anything that yields H+ or OH- respectively in water. For example, HCl (hydrochloric acid) can be described as an Arrhenius acid because in water the following reaction occurs:

pH and pOH are topics in unit 8, and AP Chemistry as a whole, that are extremely important. So then, what is pH? pH simply is a measure of the concentration of protons in a solution.