9.5 Free Energy and Equilibrium

These flashcards cover key vocabulary and concepts related to free energy and equilibrium, helping to understand the thermodynamic principles governing chemical reactions.

ΔG°

Standard Gibbs free energy change, used to determine the favorability of a reaction.

K

Equilibrium constant; a ratio that expresses the concentrations of products to reactants at equilibrium.

Thermodynamically favored

A process where ΔG° < 0, indicating that the products are favored at equilibrium.

Thermodynamically unfavorable

A process where ΔG° > 0, indicating that the reactants are favored at equilibrium.

Equilibrium constant equation

K = e^(-ΔG°/RT), relates free energy to the equilibrium constant.

Free energy equation

ΔG° = -RT ln K, used to calculate Gibbs free energy from the equilibrium constant.

When ΔG° is near zero

The equilibrium constant K will be close to 1.

K > 1

Indicates that products are favored at equilibrium.

K < 1

Indicates that reactants are favored at equilibrium.

R

Universal gas constant, 8.314 J/mol·K.

Thermodynamic favorability

A reaction is considered favorable when ΔG° is negative.

Exothermic reaction

A reaction that releases energy, usually associated with negative ΔG° values.

Entropy (ΔS)

A measure of the disorder or randomness in a system.

Enthalpy (ΔH)

Total heat content of a system, used in Gibbs free energy calculations.

ICE diagram

A table used in equilibrium chemistry to track the concentrations of reactants and products.

Ka

Acid dissociation constant; quantifies the strength of an acid in solution.

Q

Reaction quotient, used to determine the direction a reaction will proceed to reach equilibrium.

Ksp

Solubility product constant; indicates the solubility of ionic compounds.

Coulomb’s Law

Describes the force between two charged particles; used to explain solubility differences.

Gibbs free energy positive

When ΔG° > 0, the reaction is not thermodynamically favorable.

Gibbs free energy negative

When ΔG° < 0, the reaction is thermodynamically favorable.

Rank concentration

Sorting reactants/products according to their concentrations at equilibrium.

Equilibrium pressures

Partial pressures of gases in a system at equilibrium.

Thermodynamic favorability comparison

Analysis of whether a reaction moves in favor of products or reactants.

Reaction at equilibrium

A state where the forward and reverse reactions occur at the same rate.

Calculating ΔG°

Using the equation ΔG° = -RT ln K to find the free energy change.

K values interpretation

K values over 1 favor products, while values under 1 favor reactants.

Products favored

Indicates ΔG° is negative and K is greater than 1.

Reactants favored

Indicates ΔG° is positive and K is less than 1.

Units of ΔG°

Measured in J/mol in standard conditions.

Significance of K

K indicates the extent to which a reaction proceeds to completion.