Here's why:
* Temperature: Affects the kinetic energy of the molecules. Higher temperatures mean more movement and a greater likelihood of being in a gas phase. Lower temperatures mean less movement and a greater likelihood of being in a solid phase.
* Pressure: Affects the forces between molecules. Higher pressure forces molecules closer together, favoring a liquid or solid phase. Lower pressure allows molecules to spread out, favoring a gas phase.
The phase diagram shows the boundaries between these different states. It's a visual representation of how the state of matter changes with varying temperature and pressure.
