What is "bromothymol blue"

n. (context organic compound English) A dye ''4,4'-(3H-2,1 benzoxathiol-3-ylidene) bis [2 bromo-3-methyl-6-(1-methylethyl)phenol] S,S-dioxide'' that is used as an acid-base indicator

n. a dye used as an acid-base indicator [syn: bromthymol blue]

Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid. It is typically sold in solid form as the sodium salt of the acid indicator.