Why Is the Bromothymol Solution Blue?

Bromothymol blue (BMB) is an indicator dye that turns yellow in the presence of acid. When carbon dioxide is added to the solution, it creates carbonic acid, lowering the pH of the solution. BMB is blue when the pH is greater than 7.6, green when the pH is between 6-7.6, and yellow when the pH is less than 6.

What does Bromothymol blue indicate?

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.

Why did the bromothymol solution turn blue in one of the tubes?

Why did the color of the Bromthymol Blue (BTB) solution change in certain test tubes? The levels of carbon dioxide changed, therefore the BTB solution changed color to indicate the presence of carbon dioxide.