Kp Calculator
Calculate equilibrium constant in terms of partial pressure (Kp) from Kc or direct measurements
Calculate Kp
Equilibrium constant in terms of concentration
Temperature at equilibrium
Sum of stoichiometric coefficients
Sum of stoichiometric coefficients
Units for partial pressures
Δn = moles of products - moles of reactants = 0 - 0 = 0
Kp Calculation Results
Formula: Kp = Kc × (R × T)^Δn
Calculation: Kp = 0 × (0.08205746 × 298.0)^0
Gas constant: R = 0.08205746 (ATM·K/mol)
Analysis: Enter valid inputs to calculate Kp
Quick Examples
Haber Process
N₂ + 3H₂ ⇌ 2NH₃
At 298K: Kc = 2.27×10⁻²
Δn = 2 - (1+3) = -2
Water-Gas Shift
H₂O(g) + C(s) ⇌ H₂(g) + CO(g)
Kp = P₍H₂₎ × P₍CO₎ / P₍H₂O₎
NO₂ Dimerization
2NO₂(g) ⇌ N₂O₄(g)
Δn = 1 - 2 = -1
Understanding Kp - Equilibrium Constant in Terms of Pressure
What is Kp?
Kp is the equilibrium constant expressed in terms of partial pressures instead of concentrations. It's used for reactions involving gases where partial pressures are more convenient to measure than concentrations.
General Formula
Kp = Pproductscoefficients / Preactantscoefficients
For gaseous species only
Kc to Kp Conversion
Kp = Kc × (RT)Δn
Where:
- R = gas constant
- T = temperature (K)
- Δn = moles products - moles reactants
Important Considerations
Gas Constant Values
R varies based on pressure units: 0.08206 (atm), 0.08314 (bar), 8.314 (kPa)
Only Gaseous Species
Pure solids and liquids are omitted from Kp expressions (activity = 1)
When Kp = Kc
When Δn = 0 (equal moles of gaseous reactants and products)