1.2 Entropy

What is entropy

A measure of the dispersal of matter and or energy in systems. Higher entropy corresponds to a greater number of possible microstates (arrangements)

Relationship between entropy and microstates?

More microstates = higher entropy

Fewer microstates = lower entropy

Relative entropy of phases ?

Sgas​>Sliquid​>Ssolid​

Melting (solid → Liquid)

Entropy: Increases (ΔS > 0)

Why? Particles have greater freedom of motion in the liquid than in the solid increasing the number of microstates

Freexing (Liquid → Solid)

Entropy: Decreases (ΔS < 0)

Why? Particles have greater freedom of motion in the liquid than in the solid increasing the number of microstates

Vaporization/Boiling (Liquid → Gas)

Entropy: Increases (ΔS > 0)

Why? Gas particles occupy a much larger volume and have many more possible microstates than liquids

Condensation (Gas → Liquid)

Entropy: Decreases (ΔS < 0)

Why? Particles become less dispersed and the number of microstates decreases

Sublimation (Solid → Gas)

Entropy: Increases (ΔS > 0)

Why? Particles go directly from a solid to a gas greatly increasing the number of possible microstates

Deposition (Gas → Solid)

Entropy: Decreases (ΔS < 0)

Why? Particles go directly from a gas to a solid greatly decreasing the number of possible microstates