pH Unknown

The color of an acid-base indicator depends on pH. The color of the indicator called bromthymol blue is solutions whose pH varies from1 to 13 is shown here.

In these experiments you can compare the color of the indicator upon adding a sample of your unknown with the color of solutions of known pH with that indicator. In this example the colors show that the pH of the unknown is between 8 and 13.

You may have to use several indicators before you can estimate the pH of your unknown to within 1pH unit.