How this calculator works
The ideal-gas conversion uses concentrations expressed numerically in mol/L and partial pressures expressed numerically in your selected pressure unit. This conventional Kp value therefore changes with the pressure convention when the gas coefficient difference is nonzero. Thermodynamic equilibrium constants instead use dimensionless activities tied to fixed standard states. Count only gaseous species in the coefficient sums. The pressure selectors for individual species can differ; each is converted before the Kp product is formed.
Formula
Kp = Kc (Runit T)^deltaN, deltaN = sum(gas product coefficients) - sum(gas reactant coefficients). Runit = R x 1000/PaPerPressureUnit.
Worked example
For equal gas coefficient sums, deltaN = 0 and Kp = Kc = 2 at any temperature. With bar as convention, A + B in equilibrium with 2C at pressures 1, 1 and 2 bar gives Kp = 4.
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Frequently asked questions
Which gas constant is used?
The SI gas constant is converted to L times your selected pressure unit per mol per K.
Are solids included in deltaN?
No. Only gaseous stoichiometric coefficients enter this ideal-gas relationship.
Can I solve temperature if deltaN is zero?
No. Then the relationship Kp = Kc contains no temperature information.