Bromothymol blue
From Freepedia
| Bromothymol blue (pH indicator) | ||
| below pH 6.0 | above pH 7.6 | |
| yellow | ↔ | blue |
| edit this box | ||
Bromothymol blue, also known as bromthymol blue, is a chemical indicator for weak acids and bases.
The bromothymol blue acts as a weak acid in solution and therefore can be in acid or base forms which appear yellow and blue respectively. Bromothymol blue is typically sold in solid form as the sodium salt of the acid indicator. It also finds occasional use in the laboratory as a biological slide stain.
Bromothymol blue can also be used to determine the presence of carbon dioxide. If the bromothymol blue turns yellow, it means that an unknown gas is carbon dioxide.
C27H28Br2O5S ↔ H+ + C27H27Br2O5S-
The pKa for bromothymol blue is 7.10.
Formula: C21H15NaBr2O3S
Alternative name: Dibromothymolsulfonephthalein, BTB
