 We're going to look at the phase changes for carbon dioxide. We have some dry ice in a plastic pipette. At atmospheric pressure, the dry ice, the solid CO2, will sublime and go to gaseous CO2. We're going to pinch off the top of the pipette with a pair of pliers and put it into a warm water bath. As the CO2 continues to sublime, the pressure inside the pipette will increase. Eventually the pressure goes above the triple point and the CO2 liquefies. We'll see the liquid carbon dioxide in the pipette. Eventually the pressure, however, in the pipette will cause the pipette to explode. When the pipette ruptures, the pressure goes back down to one atmosphere. The liquid CO2 solidifies.