Defining Acid-Base Strength by Using Number

Acid-base system of solution can be observed by pH value. Base solution has pH value>7, neutral solution=7, and acid solution has pH value<7. The smaller the pH value of a solution is, the more acid the solution will be. The bigger the pH value of a solution is, the more base the solution will be. For example, acetic acid has pH value about 3 and ammonia has pH value about 12. So, acetic acid is acid and ammonia is base.