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

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 $H C l$ you would enter $- \log \left(.058\right)$

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 $p O H$. To get the pH you simply subtract the $p O H$ from 14.

For example, if you have a $N a O H$ solution that has a molarity of .063 you take the $- \log \left(.063\right)$ and get a $p O H$ of 1.20.

$14 - 1.20 = 12.79$

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