Bromothymol Blue pH Indicator, 1 oz.

This 0.1% aqueous bromothymol blue solution (also known as Bromthymol Blue) is a synthetic dye that is often used in solutions to indicate pH changes. Bromothymol blue changes color depending on the acidity of the solution. It is yellow at pH values below 6, blue at pH values above 7, and green at pH values between 6 and 7.6. Comes packed in convenient squeeze bottle for dispensing by the drop.

Bromothymol blue is a good indicator of dissolved carbon dioxide (CO₂). In the presence of dissolved carbon dioxide, the carbonic acid formed lowers the pH of the solution, turning the indicator from blue to green or yellow, depending on the concentration of dissolved carbon dioxide. This makes bromothymol blue ideal for biology experiments to indicate photosynthetic activity over time. The solution will turn blue as plants use up carbon dioxide or the solution will turn yellow as carbon dioxide content increases.