Equilibrium Constant Calculator
Calculate the equilibrium constant (K) from reactant and product concentrations
Calculate Equilibrium Constant
Reactants
Coefficient and concentration in molarity
Coefficient and concentration in molarity
Products
Coefficient and concentration in molarity
Equilibrium Constant Results
Formula: K = [Products]^coefficients / [Reactants]^coefficients
Analysis: K ≈ 1: Similar amounts of reactants and products at equilibrium
Magnitude: Small K (0.1-10)
Quick Examples
Synthesis of Ammonia
N₂ + 3H₂ ⇌ 2NH₃
At 500°C: K ≈ 0.1 (reactants favored)
Weak Acid Ionization
CH₃COOH ⇌ H⁺ + CH₃COO⁻
Ka = 1.8 × 10⁻⁵ (reactants favored)
Water Autoionization
2H₂O ⇌ H₃O⁺ + OH⁻
Kw = 1.0 × 10⁻¹⁴ at 25°C
Understanding Equilibrium Constants
What is an Equilibrium Constant?
The equilibrium constant (K) is a measure of the extent to which a chemical reaction proceeds to completion at a given temperature. It represents the ratio of product concentrations to reactant concentrations, each raised to the power of their stoichiometric coefficients.
General Formula
K = [C]c × [D]d / [A]a × [B]b
For the reaction: aA + bB ⇌ cC + dD
Interpreting K Values
K >> 1 (K > 100)
Products strongly favored. Reaction goes nearly to completion.
K ≈ 1 (0.1 < K < 10)
Balanced equilibrium. Significant amounts of both reactants and products.
K << 1 (K < 0.01)
Reactants strongly favored. Very little product formation.
Important Considerations
Temperature Dependence
K values change with temperature. Higher temperatures generally favor endothermic reactions.
Concentration Units
Use molarity (M) for aqueous solutions. Pure solids and liquids are not included in K expressions.
Le Chatelier's Principle
Systems at equilibrium respond to stress by shifting to counteract the change.