Bromothymol blue (BTB) is a pH indicator that turns yellow in the presence of high levels of carbon dioxide (CO) in water. If BTB is added to a water solution that has high levels of Co, the solution will turn yellow If it has no CO, the solution with BTB will remain blue
Possible colors of BTB depending of the amount of Co, presenti
ESS
more
Color blue
NO CO, or very low
Color green
Intermediate Co
Color yellow
High Co.
Students are performing an experiment to understand the transfers of carbon between a photosynthetic organism, the aquatic plant Elodea, and a water snail. They are using test tubes that contain the same
amount of water, partially enriched in CO2, and the same amount of BTB, to detect the presence of Co, The test tubes are placed in natural sunlight for the duration of the experiment, as shown in the image. The
contents of each test tube are as follows: