A safe and inexpensive laboratory for a first-year general chemistry course has been developed which allows students to explore important properties of carbon dioxide, particularly its behavior as a greenhouse gas. Students witness and measure air displacement to compare calculated gas densities and pressures inside a CO[subscript 2]-filled balloon with those of the surrounding air; because the balloon is permeable to CO[subscript 2], students can determine the average rate of CO[subscript 2] loss from the balloon. A loosely sealed centrifuge tube containing dry ice allows students to briefly observe liquid CO[subscript 2] and to map that experience onto the phase diagram of CO[subscript 2] discussed in lecture. Students simulate the ability of CO[subscript 2] to act as a greenhouse gas by measuring differences in heat retention in the presence and absence of a CO[subscript 2]-enriched atmosphere within an open beaker containing gravel that serves as a model Earth system. Student reflections indicate substantial gains in a more scientifically rigorous understanding of the role of greenhouse gases in the heating of the atmosphere.