Indicators Acids and Bases
How can you distinguish an acid from a base? How can you detect acids and bases in some substances in solution? You can do these with the use of complex organic substances known as acid-base indicators. These substances show distinct color changes when they come in contact with an acid or a base.
There are several indicators available. Four of them are shown in the following table.
| Indicators | Color in Acid | Color in Base |
|---|---|---|
| Litmus | red | blue |
| Universal | red | violet |
| Methyl orange | red | yellow |
| Phenolphthalein | colorless | pink |
Indicators can also be prepared from certain plants. The red, purple, and blue colors of these plants indicate that they contain an organic substance called anthocyanin. Extracts from these plants change their color when they are exposed to compounds that are acidic or basic in nature.
