Phase Transition¶
Phase transition is when a substance changes from a solid, liquid, or gas state to a different state. Every element and substance can transition from one phase to another at a specific combination of temperature and pressure.
Phase transition can be represented with a phase diagram. A phase diagram is a visual representation of how a substance changes phases.
Basic Phase Diagram¶
These diagrams usually have the normal boiling point and normal melting point marked on them, and have the pressures on the y-axis and temperatures on the x-axis.
What does this diagram show?¶
- Critical Point: At a temperature of 364 °C and a pressure of 218 atm, this is the point where there is equilibrium between the liquid and gas phases, any point above the critical point is a point where liquids cease to exist
- Triple Point: At a temperature of 0.01 °C and a pressure of 0.0060 atm, this is the point where liquid, gas, and solids exist in equilibrium
- Freezing Point: At a temperature of 0 °C and a pressure of 1.00 atm, this is the point at which water (liquid) freezes into ice (a solid)
- Boiling Point: At a temperature of 100.0 °C and a pressure of 1.00 atm, this is the point at which water (liquid) boils, turning it into a water vapor (gas)
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