Adding Carbon Dioxide to a BTB Solution

This interactive illustrates how the pH of a Bromothymol blue (BTB) solution changes when carbon dioxide is added. The pH change is measured by the color change of the pH indicator BTB. BTB is blue at a pH over 8, yellow at a pH below 6, and shades of green in between.   Instructions: Drag the slider to see how the pH of the BTB solution changes over time when carbon dioxide is blown into it.