E

Equilibrium

K = [C]^c[D]^d/([A]^a[B]^b); ΔG = ΔG° + RT ln Q
Quick Reference
Formula / NotationK = [C]^c[D]^d/([A]^a[B]^b); ΔG = ΔG° + RT ln Q
Also Known AsChemical equilibrium, dynamic equilibrium, K_eq, reaction equilibrium

What is Equilibrium?

The state of a reversible chemical reaction at which the rates of the forward and reverse reactions are equal and the concentrations of reactants and products remain constant. Equilibrium does not mean equal concentrations, but rather constant concentrations over time.

Formula & Notation

K = [C]^c[D]^d/([A]^a[B]^b); ΔG = ΔG° + RT ln Q

Other Names / Synonyms: Chemical equilibrium, dynamic equilibrium, K_eq, reaction equilibrium

Properties & Characteristics

Equilibrium is the state of a reversible process (chemical reaction, phase transition, or dissolution) in which the forward and reverse rates are equal, resulting in constant macroscopic properties. Chemical equilibrium is quantified by the equilibrium constant K (Kc in concentration terms, Kp in pressure terms). The reaction quotient Q relative to K predicts direction of spontaneous change: Q < K → forward; Q > K → reverse. Temperature affects K via the van't Hoff equation.

Uses & Applications

Equilibrium concepts are applied in industrial chemical processes (optimising yield via Le Chatelier's principle), acid-base chemistry (Ka, Kb, Kw), solubility (Ksp), complexation (formation constants), biochemistry (enzyme active sites, protein folding), and environmental chemistry.

Safety Information

Processes approaching equilibrium may release hazardous species if conditions change. A reaction "at equilibrium" still has both reactant and product present — the reaction has not stopped. Understanding equilibrium prevents the false assumption that a reaction is "complete" when it reaches equilibrium.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Equilibrium
Formula K = [C]^c[D]^d/([A]^a[B]^b); ΔG = ΔG° + RT ln Q
Synonyms Chemical equilibrium, dynamic equilibrium, K_eq, reaction equilibrium

Frequently Asked Questions

The state of a reversible chemical reaction at which the rates of the forward and reverse reactions are equal and the concentrations of reactants and products remain constant. Equilibrium does not mean equal concentrations, but rather constant concentrations over time.

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