Lecture 6: Thermodynamics and Gibbs Free Energy

These flashcards cover key vocabulary related to thermodynamics, Gibbs Free Energy, and equilibrium concepts discussed during the lecture.

Entropy

A measure of the disorder or randomness of a system, related to the number of microscopic configurations that correspond to a thermodynamic system's macroscopic state.

Gibbs Free Energy (G)

The energy associated with a chemical reaction that can be used to do work; it is defined as G = H - TS, where H is enthalpy, T is temperature, and S is entropy.

Equilibrium Constant (K)

A dimensionless value that gives the ratio of the concentrations of products to reactants at equilibrium conditions; can be expressed as Kp for gases and Kc for solutions.

Spontaneous Reaction

A chemical reaction that occurs without the need for an input of energy; characterized by a decrease in Gibbs Free Energy (ΔG < 0).

Activity

A dimensionless quantity used to express the effective concentration of a species in a mixture, considering interactions between particles.

Exergonic Process

A spontaneous chemical reaction that releases energy, indicated by a negative change in Gibbs Free Energy (ΔG < 0).

Endergonic Process

A non-spontaneous chemical reaction that requires energy input, indicated by a positive change in Gibbs Free Energy (ΔG > 0).

Standard Entropy (S°)

The entropy of a substance in its standard state, typically defined at 1 atm pressure and a specified temperature, often 25°C.

Phase Transition and Entropy

Entropy increases during phase transitions such as melting or boiling, where the number of microstates increases.

Chemical Equilibrium

A state in which the concentrations of reactants and products remain constant over time, as their rates of formation and decomposition are equal.