What does the Equilibrium Constant Calculator compute?

It computes the equilibrium constant Kc for a chemical reaction of the form aA + bB ⇌ cC + dD, using the molar concentrations (mol/L) and stoichiometric coefficients you enter for two products and two reactants.

How is Kc calculated from the inputs?

Kc = ([C]^c * [D]^d) / ([A]^a * [B]^b), where [C] and [D] are product concentrations, [A] and [B] are reactant concentrations, and a, b, c, d are their respective stoichiometric coefficients.

What units should I use for concentrations?

Concentrations must be entered in mol/L (molarity). The calculator uses these values directly in the Kc expression, so ensure all concentrations are in the same unit.

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Equilibrium Constant Calculator.

Calculate Kc for two explicit product and reactant species and their stoichiometric coefficients.

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02 / 答案

Product A concentration

Product A coefficient

Product B concentration

Product B coefficient

Reactant A concentration

Reactant A coefficient

Reactant B concentration

Reactant B coefficient

使用方法

Kc = (Aproducts^ν × Bproducts^ν) ÷ (Areactants^ν × Breactants^ν). Concentrations and coefficients are visible inputs.

Use a named source for any material-specific coefficient. This page does not infer local rates, species tables, laboratory methods, or safety guidance.

Use Cases

Determine Kc for a balanced reaction

Use this calculator to find the equilibrium constant for any reaction with two products and two reactants, given their equilibrium concentrations and coefficients.

Example: For N2 + 3H2 ⇌ 2NH3, enter [NH3]=0.5, coefficient 2; [N2]=0.1, coefficient 1; [H2]=0.3, coefficient 3.

Check consistency of equilibrium data

Verify whether given concentration data and coefficients yield a plausible Kc value, useful for lab reports or textbook problems.

Example: Compare calculated Kc with literature values to validate experimental measurements.

Frequently Asked Questions

What does the Equilibrium Constant Calculator compute?: It computes the equilibrium constant Kc for a chemical reaction of the form aA + bB ⇌ cC + dD, using the molar concentrations (mol/L) and stoichiometric coefficients you enter for two products and two reactants.
How is Kc calculated from the inputs?: Kc = ([C]^c * [D]^d) / ([A]^a * [B]^b), where [C] and [D] are product concentrations, [A] and [B] are reactant concentrations, and a, b, c, d are their respective stoichiometric coefficients.
What units should I use for concentrations?: Concentrations must be entered in mol/L (molarity). The calculator uses these values directly in the Kc expression, so ensure all concentrations are in the same unit.

Tips & Common Mistakes

Tips

Ensure the chemical equation is balanced before entering coefficients; otherwise, Kc will be incorrect.
Use consistent units (mol/L) for all concentrations. If concentrations are given in other units, convert them first.
Double-check that you have assigned products and reactants correctly; swapping them will invert Kc.
For reactions with pure solids or liquids, their concentrations are constant and not included in Kc; this calculator only handles species with variable concentrations.

Common Mistakes to Avoid

Forgetting to raise each concentration to the power of its stoichiometric coefficient.
Entering coefficients as concentrations or vice versa, leading to a nonsensical Kc.
Using concentrations at non-equilibrium conditions; Kc is only defined at equilibrium.

Last updated: August 13, 2026