Bromothymol blue solution 0.04 %, alcoholic, is mainly used in medical diagnostics and histology. It consists of bromothymol blue, a pH indicator, and ethanol as a solvent. The chemical formula of bromothymol blue is C27H28Br2O5S and that of ethanol is C2H6O.
Due to the chemical properties of bromothymol blue, this solution shows different color depending on pH: yellow at pH below 6.0, green at pH around 6.0 and blue at pH above 7.6, so it is used in laboratories to determine the pH of solutions. It does not react chemically, but changes color depending on the concentration of hydrogen ions in the solution being tested.
When used in histology, the solution allows visible differentiation between different cell types or organelles, which contributes to accurate diagnosis.
SDS for Alcohloic bromothymol Blue
Why is phenolphthalein used as an indicator for a strong acid and a strong base titration rather than bromothymol blue when phenolphthalein has a pH range of 8.3-10 whereas for bromothymol blue it is 6.0-7.6?
Phenolphthalein is commonly used as an indicator in strong acid-strong base titrations because it changes color in a pH range of 8.3 to 10.0, which is close to the equivalence point of the titration. At the equivalence point, the pH of the solution is usually around 7 to 10, so phenolphthalein is a good indicator as it changes color in this range. On the other hand, bromothymol blue has a pH range of 6.0 to 7.6, which is not ideal for strong acid-strong base titrations, as the equivalence point is usually above this range. Bromothymol blue is more commonly used as an indicator in weak acid-strong base and weak base-strong acid titrations, where the equivalence point occurs within its pH range. In summary, phenolphthalein is a suitable indicator for strong acid-strong base titrations because its pH range is close to the equivalence point of the titration. Bromothymol blue is more suitable for weak acid-strong base and weak base-strong acid titrations.