Thermodynamics and Equilibrium

These flashcards cover key terms and concepts from the lecture on Thermodynamics and Equilibrium, focusing on entropy, free energy, and thermodynamic laws.

Entropy (S)

A thermodynamic quantity that measures how dispersed the energy of a system is among the different possible ways that system can contain energy.

First Law of Thermodynamics

States that the change in internal energy (ΔU) of a system equals the sum of heat (q) added to the system and work (w) done on the system, expressed as ΔU = q + w.

Second Law of Thermodynamics

States that the total entropy of a system and its surroundings always increases for a spontaneous process.

Spontaneous Process

A physical or chemical change that occurs by itself without requiring any outside force, continuing until equilibrium is reached.

Gibbs Free Energy (G)

A thermodynamic quantity defined as G = H - TS, used to determine spontaneity of a reaction.

Criterion for a Spontaneous Reaction

The criterion is that the entropy of the system and its surroundings must increase (ΔS > 0).

Third Law of Thermodynamics

A substance that is perfectly crystalline at zero Kelvin (0 K) has an entropy of zero.

Heat (q) Sign Convention

When heat is evolved by the system, q is negative; when heat is absorbed by the system, q is positive.

Entropy Change (ΔS) Calculation

For a reaction, ΔS is calculated using ΔS = ΣnS° (products) - ΣnS° (reactants).

Free Energy Change (ΔG)

The change in free energy is calculated as ΔG° = ΔH° - TΔS°, indicating spontaneity based on its sign.