Where do strong acids and bases fall on the pH scale?

1 Answer
Nov 9, 2015

Acids are lower, bases are higher on the pH scale.

Explanation:

When determining the pH of a strong acid or base you should be given a concentration in molarity (moles/liter).

Since strong acids and bases completely disassociate in water you can take the log of the molarity. For example, if you were asked to find the pH of a .058 M solution of HCl you would enter log(.058)

You can see that it would have a pH of 1.23

You do the same thing for strong bases, but you have to remember that the answer that you will get will be pOH. To get the pH you simply subtract the pOH from 14.

For example, if you have a NaOH solution that has a molarity of .063 you take the log(.063) and get a pOH of 1.20.

141.20=12.79

From that information you can see that acidic solutions have a lower pH and basic solutions have a higher pH.