Equilibrium & Gibbs Free Energy

Vocabulary flashcards based on entropy, Gibbs Free Energy, and thermodynamics concepts from lecture notes.

Enthalpy (ΔH)

The change in heat energy of a chemical reaction.

Exothermic reaction

A reaction where ΔH is negative and heat is released.

Endothermic reaction

A reaction where ΔH is positive and heat is absorbed.

Entropy (ΔS)

Measures the amount of disorder or randomness in a system.

Spontaneous process

A process that occurs without needing to be driven by an outside force.

Units for Entropy (ΔS)

KJ/K for ΔS and J/mol∙K for S.

Gibbs Free Energy (G)

The energy available to do work, taking into account entropy and enthalpy.

ΔG < 0

Indicates that a reaction is spontaneous.

ΔG = 0

Indicates that the system is in a state of dynamic equilibrium.

Spontaneity of reactions

A reaction may be spontaneous if the entropy increase is sufficient to offset the energy needed for reaction.

First Law of Thermodynamics

Energy can neither be created nor destroyed.

Second Law of Thermodynamics

The total entropy of the universe must increase in every spontaneous process.

Third Law of Thermodynamics

The entropy of a perfectly crystalline substance at absolute zero is zero.

Heat Transfer

In an exothermic reaction, heat is transferred to the surroundings.

ΔS of a reaction

Calculated by subtracting the entropy of the reactants from the entropy of the products.

Haber process

A method for producing ammonia from nitrogen and hydrogen gas.

Combustion Reaction

A reaction involving the burning of a substance, often releasing energy.

Thermal Equilibrium

Occurs when two bodies are at the same temperature.

Coherent Pathway

The condition under which a process is deemed reversible.

Dynamic Equilibrium

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

Phase Change

The transition of a substance from one state of matter to another due to changes in temperature or pressure.