Gibbs Free Energy and Chemical Equilibrium

Gibbs Free Energy (ΔG)

Indicates spontaneity of a chemical reaction.

Spontaneous Reaction

Occurs without external energy input; ΔG < 0.

Nonspontaneous Reaction

Requires energy input; ΔG > 0.

Equilibrium Condition

No net change; ΔG = 0.

Standard Free Energy Change (ΔG0)

Free energy change under standard conditions.

Reaction Quotient (Q)

Ratio of products to reactants at any time.

Absolute Temperature (T)

Temperature measured in Kelvin (K).

Free Energy Equation

ΔG = ΔHsys - TΔSsys.

Equilibrium Constant (K)

Value of Q at equilibrium; Q = K.

Van't Hoff Equation

Relates equilibrium constants at different temperatures.

Slope of K vs 1/T Plot

Determined by enthalpy change; positive for exothermic.

Enthalpy Change (ΔH0)

Heat change during a reaction at constant pressure.