Addresses AP® Chemistry Big Idea 6 and Learning Objective 6.9. Investigate how temperature, concentration, and pressure affect chemical equilibrium in 3 different reactions. This experiment addresses equilibrium changes both in solution and in the gas phase, shows the reversible nature of reactions, and provides visual interest by using changes in color to monitor chemical reactions. It also includes a discussion of the Haber process. For 30 students working in teams of 3.