# If you titrate nitric acid with sodium hydroxide, you will add a drop or two of phenolphthalein to the sample of acid before you begin adding the sodium hydroxide. Why is the indicator added?

Nov 16, 2015

The Acid-Base indicator from its name it means that it will indicate that the equivalence point (or end point) of the titration is reached.

#### Explanation:

The Acid-Base indicator from its name it means that it will indicate that the equivalence point (or end point) of the titration is reached.

At the equivalence point, ${n}_{{H}^{+}} = {n}_{O {H}^{-}}$.

The phenolphthalein is an acid-base indicator that is colourless in acidic medium and $\textcolor{\pi n k}{\text{pink}}$ in basic solution.

Watch this video that explains in details the acid - base titration.
Lab Demonstration | Acid - Base Titration.