Final answer:
A phase diagram shows the relationship between the phases of a substance at different temperatures and pressures. It includes the triple point, melting point curve, vapor pressure curve, and sublimation curve. These curves represent the different phase transitions of the compound.
Step-by-step explanation:
A phase diagram is a graphical representation of the phases of a substance at different temperatures and pressures. It shows the relationship between the solid liquid and gas phases of the compound. The triple point is the specific temperature and pressure at which all three phases coexist in equilibrium. The vapor pressure curve represents the conditions at which the compound exists in the gas phase, while the melting point curve represents the conditions at which it transitions from the solid phase to the liquid phase.