Entropy, Free Energy, and Equilibrium - Flashcards

Vocabulary flashcards covering the key principles of thermodynamics including the laws of thermodynamics, entropy, and Gibbs free energy based on lecture notes.

Entropy (S)

A measure of the randomness or disorder of a system.

Microstates (W)

The number of different ways the energy of a system can be distributed, used in the formula $S = k \text{ ln } W$.

BoPtzmann Equation

The formula $S = k \text{ ln } W$ relating entropy to the number of microstates.

Standard Entropy of Reaction ($\Delta S^0_{rxn}$)

The entropy change for a reaction carried out at $1\text{ atm}$ and $250C$.

State functions

Properties that are determined by the state of the system, regardless of how that condition was achieved, such as energy, enthalpy, pressure, volume, temperature, and entropy.

First Law of Thermodynamics

Energy can be converted from one form to another but energy cannot be created or destroyed.

Second Law of Thermodynamics

The entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process.

Third Law of Thermodynamics

The entropy of a perfect crystalline substance is zero at the absolute zero of temperature.

Gibbs Free Energy (G)

For a constant-temperature process, it is defined by the equation $\Delta G = \Delta H_{sys} - T\Delta S_{sys}$.

Standard free-energy of reaction ($\Delta G^0_{rxn}$)

The free-energy change for a reaction when it occurs under standard-state conditions.

Standard free energy of formation ($\Delta G^0_f$)

The free-energy change that occurs when $1\text{ mole}$ of the compound is formed from its elements in their standard states.

Spontaneous process

A process where the change in free energy is negative ($\Delta G < 0$) or the change in entropy of the universe is greater than zero ($\Delta S_{univ} > 0$).

Equilibrium process

A process where the change in free energy is zero ($\Delta G = 0$) and the change in entropy of the universe is zero ($\Delta S_{univ} = 0$).

Gas Constant (R)

A constant used in the Gibbs Free Energy and Chemical Equilibrium equation, equal to $8.314\text{ J/K} \cdot \text{mol}$.

Reaction Quotient (Q)

A value used in the equation $\Delta G = \Delta G^0 + RT \text{ ln } Q$ to determine the free energy change under non-standard conditions.