Equilibrium Constant Solver Calculator

Compute Kc, Kp, and Gibbs energy from inputs. Switch modes for conversions, constants, and diagnostics. Explore equilibrium behavior with exports, formulas, tables, and guidance.

Calculator

Use equilibrium concentrations or equilibrium partial pressures only. Omit pure solids and pure liquids from the expression.

Products

Product 1

Product 2

Product 3

Reactants

Reactant 1

Reactant 2

Reactant 3

This mode solves standard Gibbs free energy from the selected equilibrium constant.

Example Data Table

Sample reaction at equilibrium: N2 + 3H2 ⇌ 2NH3 at 700 K.

Species Role Coefficient Equilibrium Concentration (mol/L)
N2 Reactant 1 0.50
H2 Reactant 3 0.20
NH3 Product 2 1.10

For this sample, Kc = (1.102) / (0.50 × 0.203) = 302.50. Since Δn = 2 − 4 = −2, Kp at 700 K is about 0.09166.

Formula Used

Equilibrium constant from concentrations

Kc = ∏[Products]coefficient / ∏[Reactants]coefficient

Equilibrium constant from pressures

Kp = ∏(Partial Pressures of Products)coefficient / ∏(Partial Pressures of Reactants)coefficient

Conversion between Kc and Kp

Kp = Kc(RT)Δn, where Δn = total gaseous product coefficients − total gaseous reactant coefficients.

Gibbs free energy relationship

ΔG° = −RT ln(K), and rearranging gives K = e−ΔG°/RT.

This calculator treats entered concentrations or partial pressures as activities for practical solving. Keep units consistent and omit pure solids and liquids from the equilibrium expression.

How to Use This Calculator

  1. Choose a calculation mode that matches your problem.
  2. For direct solving, enter product and reactant names, coefficients, and equilibrium values.
  3. Select concentration basis for Kc or pressure basis for Kp.
  4. Enter temperature when you want ΔG° or Kc/Kp conversion.
  5. Press Solve Now to display the result above the form.
  6. Use the CSV button to save a spreadsheet-style result summary.
  7. Use the PDF button to generate a clean result document.

FAQs

1. What does this solver calculate?

It solves Kc or Kp from equilibrium data, converts between Kc and Kp, finds ΔG° from K, and computes K from ΔG°.

2. Should solids and liquids be included?

No. Pure solids and pure liquids are omitted from the equilibrium expression because their activity is treated as constant.

3. When should I use Kc instead of Kp?

Use Kc when your equilibrium data are concentrations. Use Kp when the reaction is expressed with gaseous partial pressures.

4. Why is temperature important?

Temperature is required for Kc to Kp conversion and for linking the equilibrium constant with standard Gibbs free energy.

5. What does a large K value mean?

A large equilibrium constant means products are favored at equilibrium. A very small value means reactants are favored.

6. Can I use decimal stoichiometric coefficients?

Yes. The solver accepts positive decimal coefficients, although balanced whole-number coefficients are usually preferred for interpretation.

7. What unit should ΔG° use?

You can enter ΔG° in either kJ/mol or J/mol. The calculator converts it internally before solving for K.

8. Why might Kc and Kp be different?

They differ when the total gaseous mole count changes during reaction progress. That difference is captured by Δn in the conversion formula.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.