Bromothymol blue is used as an indicator in many laboratory reactions. This is a dye that is considered to be pH sensitive.
Bromothymol blue is a pH indicator that determines if something is a weak base or acid. It is primarily used by applications that require the measuring of substances that have a fairly neutral pH. An example of such an application would be something to manage the pH of pools. Often, bromothymol blue will be sold in solid form, as sodium salt of the acid indicator. It can be either yellow or blue, depending on the pH of the substance which it is testing. Bromothymol blue is somewhat soluble in water, though it is entirely soluble in ether, alcohol, and aqueous solutions of alkali.