There are several aspects of chemistry that utilize graphs to represent data. One example is the relationship between pressure and temperature on the phases of matter. These phase diagrams describe the changes in physical properties of matter when temperature and/or pressure changes. You can see from the diagram for carbon dioxide below (Figure 1), the conditions under which CO2 solid, liquid, or gas would exist.

2.“Dry ice” is solid CO2 and must be kept at very cold temperatures or else it will sublime (sublimation is the direct phase change from a solid to a gas). Using the phase diagram (Figure 1), determine the temperature at which CO2 would sublime under atmospheric pressure (1 atm).

3.Which phase change is occurring when the pressure of a sample of CO2 is decreased from 73 atm to 5 atm at a constant temperature of 30oC?