Phase Diagrams

Understanding Phase Diagrams and States of Matter

The Role of Temperature and Pressure in States of Matter

• The state or phase of a substance is influenced by both temperature and pressure, not solely temperature.

• A phase diagram illustrates the conditions (temperature and pressure) under which a substance exists as solid, liquid, or gas (vapor).

Key Points on Water's Phase Diagram

• At standard pressure (101.3 kPa), water has a melting point at 0°C and a boiling point at 100°C.

• Lower pressures result in higher melting points and lower boiling points for water.

Unique Conditions: Triple Point and Sublimation

• The triple point is where solid, liquid, and gas phases coexist in equilibrium; particles can transition between these states.

• Sublimation occurs under low pressure and temperature; some substances like dry ice can sublimate at room temperature.

Real-Life Examples of Sublimation

• Ice cubes left in the freezer shrink over time due to sublimation occurring at cold temperatures.

Practical Applications of Phase Diagrams

• Phase diagrams are useful tools for determining the conditions necessary for phase changes across various substances.