How to use the equilibrium constant calculator
Calculate Kc from concentrations for aA + bB ⇌ cC + dD. Enter [c], [d], [a], [b], coeff of c, coeff of d, coeff of a, coeff of b in the fields above; the kc is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- C — [C] (mol/L)
- D — [D] (mol/L)
- A — [A] (mol/L)
- B — [B] (mol/L)
- c — Coeff of C
- d — Coeff of D
- a — Coeff of A
- b — Coeff of B
Worked example
With [c] = 0.4 mol/L, [d] = 0.3 mol/L, [a] = 0.2 mol/L, [b] = 0.1 mol/L, coeff of c = 1, coeff of d = 1, coeff of a = 1, coeff of b = 1, the calculator gives kc ≈ 6.
Frequently asked questions
What is the formula for the equilibrium constant calculation?
Kc = (C^c × D^d) / (A^a × B^b). Here C is [c] (mol/L), D is [d] (mol/L), A is [a] (mol/L), B is [b] (mol/L), c is coeff of c, d is coeff of d, a is coeff of a, b is coeff of b.
What inputs do I need for the equilibrium constant (kc) calculator?
You need [c] in mol/L, [d] in mol/L, [a] in mol/L, [b] in mol/L, coeff of c, coeff of d, coeff of a, coeff of b. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.