E

Equilibrium Constant

K = [C]^c[D]^d / [A]^a[B]^b
Quick Reference
Formula / NotationK = [C]^c[D]^d / [A]^a[B]^b
Also Known AsKeq, Kc, Equilibrium expression, Mass action expression

What is Equilibrium Constant?

A dimensionless number (K) that expresses the ratio of products to reactants at equilibrium, with each concentration raised to the power of its stoichiometric coefficient. K > 1 favors products; K < 1 favors reactants. Temperature changes alter the value of K.

Formula & Notation

K = [C]^c[D]^d / [A]^a[B]^b

Other Names / Synonyms: Keq, Kc, Equilibrium expression, Mass action expression

Properties & Characteristics

Dimensionless number. K >> 1 means products strongly favored; K << 1 means reactants favored. K depends only on temperature (not concentration or pressure changes). Kp relates to Kc by: Kp = Kc × (RT)^Δn. Kw = 1.0 × 10⁻¹⁴ (water autoionization at 25°C). Ka × Kb = Kw for any conjugate acid-base pair.

Uses & Applications

Predicting equilibrium product yields in industrial syntheses. Designing buffer solutions. Calculating ion concentrations in solution. Optimizing the Haber process for ammonia production. Understanding enzyme-substrate binding affinities in biochemistry. Environmental chemistry: predicting pollutant speciation in water.

Safety Information

No direct hazard from the constant itself. It is used as a calculation tool to predict whether reactions will generate hazardous products or reach dangerous extremes of conversion.

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

Key Facts

Term Equilibrium Constant
Formula K = [C]^c[D]^d / [A]^a[B]^b
Synonyms Keq, Kc, Equilibrium expression, Mass action expression

Frequently Asked Questions

A dimensionless number (K) that expresses the ratio of products to reactants at equilibrium, with each concentration raised to the power of its stoichiometric coefficient. K > 1 favors products; K < 1 favors reactants. Temperature changes alter the value of K.

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