Students conduct experiments designed to detect the presence of CO2 by using a BTB that changes color (blue to yellow) in the presence of CO2. First, students experiment with the CO2 from combining vinegar and baking soda. In part two, students analyze CO2 from car exhaust, their breath, and the outside air. The third part of the lab, includes bubbling CO2 through a BTB solution through a titration by ading small volumes of a base solution to the BTB mixture.