Entropy and Gibbs Energy Lecture Notes

This flashcard set covers the fundamental vocabulary and concepts of chemical thermodynamics, including spontaneity, enthalpy, entropy, and Gibbs Free Energy based on Chapter 15 lecture notes.

Thermodynamics

The study of initial states, final states, and spontaneity to predict whether a process will occur under given conditions.

Kinetics

The study of intermediate states and the speed or rate at which a chemical process occurs.

Spontaneous Process

A process that will occur under given conditions without a continuous input of energy; it involves a net release of energy and is irreversible.

Nonspontaneous Process

A process that requires a continuous input of energy to proceed.

Reversible Process

A process at equilibrium that proceeds back and forth between two end conditions, resulting in no change in free energy.

Enthalpy Change ($\Delta H$)

The difference between the sum of internal energy and PV work energy of the reactants and products, generally measured in $kJ/mol$.

Exothermic

A reaction where the bonds in the products are stronger than the bonds in the reactants, leading to a negative $\Delta H$ and a release of energy.

Endothermic

A reaction where the bonds in the products are weaker than those in the reactants, resulting in a positive $\Delta H$ and absorption of energy.

Entropy ($S$)

A thermodynamic function that increases as the number of energetically equivalent ways of arranging the components increases; measured in $J/mol$.

Second Law of Thermodynamics

The law stating that the total entropy change of the universe ($\Delta S_{univ}$) must be positive for a process to be spontaneous.

Standard Absolute Entropies ($S^\circ$)

Entropy values measured for $1\,mol$ of a substance at $298\,K$ under standard state conditions for a particular state and allotrope.

Gibbs Free Energy ($G$)

The maximum amount of work energy that can be released to the surroundings by a system at constant temperature and pressure, often called chemical potential.

Extensive Property

A property, such as entropy or Gibbs free energy, that depends on the amount of matter present.

Molecular Complexity

A factor where larger, more complex molecules have higher entropy because more energy states (translational, rotational, vibrational) are available for energy dispersal.

Standard Free Energy of Formation ($\Delta G^\circ_f$)

The change in free energy when $1\,mol$ of a compound is formed from its constituent elements in their standard states; elements in their standard state have a value of zero.

Reaction Quotient ($Q$)

A value used to determine the free energy change under nonstandard conditions using the equation $\Delta G = \Delta G^\circ + RT \ln(Q)$.

Ideal Gas Constant ($R$)

The constant used in thermodynamic equations with the value $8.314\,J/mol \cdot K$.

Equilibrium Constant ($K$) Relation

The relationship between standard free energy and equilibrium defined by the equation $\Delta G^\circ = -RT \ln(K)$; spontaneous in the forward direction when $K > 1$.