Kp Calculator (Chemical Equilibrium
### Gas-Phase Chemical Equilibrium Mechanics In chemical thermodynamics, the equilibrium constant can be expressed either in terms of molar concentrations (Kc) or partial pressures (Kp). ### The Kp.
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📐 Formula
💡 Practical Example
For the Haber-Bosch reaction N2 + 3H2 <=> 2NH3 at 500 K with Kc = 0.50 and Δn = 2 - 4 = -2: The thermal factor RT = 41.0287 L*atm/mol, scaling factor (RT)^-2 = 5.9405e-4, resulting in Kp = 2.9702e-4.
📖 About Kp Calculator (Chemical Equilibrium
Gas-Phase Chemical Equilibrium Mechanics
In chemical thermodynamics, the equilibrium constant can be expressed either in terms of molar concentrations (Kc) or partial pressures (Kp).
The Kp = Kc(RT)^Δn Derivation
Using the Ideal Gas Law P V = n R T => P = R T = C R * T, substituting partial pressures into the Kp expression yields:
- Reaction Standard Form: aA + bB <=> cC + dD
- Gas Moles Net Change: Δn = -
- Fundamental Relation: Kp = Kc *^Δn
- Gas Constant Value: R = 0.0820573 L*atm/ (when pressure is in atmospheres)
- Temperature Constraint: T must always be supplied in absolute Kelvin
Special Case Δn = 0
When the total number of moles of gaseous products equals the total moles of gaseous reactants, (RT)^0 = 1, making Kp equal to Kc.
How to Use This Calculator
Enter your Equilibrium Constant (Kc) (e.g. e.g. 0.50), Absolute Temperature (T) (e.g. e.g. 500 in K), and Change in Moles of Gas (Δn = n_prod - n_react) (e.g. e.g. -2 in moles). Results update instantly as you type — adjust any value to compare scenarios.
The Formula
Universal gas constant R = 0.0820573 L·atm/(mol·K)
Worked Example
For the Haber-Bosch reaction N2 + 3H2 <=> 2NH3 at 500 K with Kc = 0.50 and Δn = 2 - 4 = -2: The thermal factor RT = 41.0287 L*atm/mol, scaling factor (RT)^-2 = 5.9405e-4, resulting in Kp = 2.9702e-
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