Kp Calculator — Equilibrium Constant in Partial Pressures
Convert the concentration equilibrium constant (Kc) to the pressure equilibrium constant (Kp) using the ideal-gas relationship Kp = Kc × (RT)^Δn, and derive the standard Gibbs free energy change ΔG° = −RT ln Kp at any temperature.
K
Kp expressed in terms of partial pressures (atm units)
- 1
RT (L·atm/mol)
0.082057 × 298 = 24.4531 - 2
(RT)^Δn
24.4531^1 = 24.453087 - 3
Kp = Kc × (RT)^Δn
0.0821 × 24.453087 = 2.0076Kp relates partial pressures; Kc relates molar concentrations. The (RT)^Δn factor bridges the two.
यह कैलकुलेटर कैसे काम करता है?
Kp = Kc × (RT)^Δn, where R = 0.082057 L·atm/(mol·K), T is temperature in kelvin, and Δn = moles of gaseous products minus moles of gaseous reactants. If Δn = 0, Kp = Kc. Standard Gibbs energy ΔG° = −RT ln Kp: negative ΔG° means products are favoured.
सूत्र
How this is calculated
At chemical equilibrium the reaction quotient equals the equilibrium constant. Two equivalent forms exist: Kc uses molar concentrations [mol/L] while Kp uses partial pressures [atm]. For an ideal gas, the partial pressure of component i equals [i]RT, so the ratio of Kp to Kc carries a factor of (RT)^Δn, where Δn is the net change in the number of moles of gaseous species: Δn = Σn(gaseous products) − Σn(gaseous reactants). If Δn = 0 (equal moles of gas on both sides), Kp = Kc exactly.
The gas constant R = 0.082057 L·atm/(mol·K) is used here because Kp is expressed in atmospheres. If you need Kp in SI pascals you would use R = 8.314 J/(mol·K) with pressure in Pa — the numerical value of Kp changes, but the equilibrium position does not.
The standard Gibbs free energy change ΔG° = −RT ln Kp (R = 8.314 J/mol·K) quantifies whether the reaction is thermodynamically spontaneous under standard conditions: ΔG° < 0 means products are favoured (Kp > 1); ΔG° > 0 means reactants are favoured (Kp < 1); ΔG° = 0 means Kp = 1. This calculator assumes ideal-gas behaviour and does not account for fugacity corrections at high pressure.
अक्सर पूछे जाने वाले प्रश्न
Kp = Kc whenever Δn = 0, i.e. when the number of moles of gaseous products equals the number of moles of gaseous reactants. Example: H₂(g) + I₂(g) ⇌ 2 HI(g) has Δn = 2 − 2 = 0, so Kp = Kc at any temperature.
A large Kp (≫ 1) indicates the equilibrium lies strongly toward products — the reaction proceeds nearly to completion under those conditions. A small Kp (≪ 1) means the equilibrium favours reactants and very little product forms. Kp = 1 means products and reactants coexist in roughly equal concentrations at equilibrium.
No. At constant temperature, Kp is a true constant and does not change when total pressure is altered — only the position of equilibrium shifts (Le Chatelier's principle). Kp changes only when temperature changes, which is described by the van't Hoff equation.
इस नाम से भी जाना जाता है
TG we-Calculate Editorial Team. (2026). Kp Calculator — Equilibrium Constant in Partial Pressures [Online calculator]. TG we-Calculate. https://we-calculate.com/hi/calculator/kp-calculator
TG we-Calculate Editorial Team. "Kp Calculator — Equilibrium Constant in Partial Pressures." TG we-Calculate. 2026. https://we-calculate.com/hi/calculator/kp-calculator.
TG we-Calculate Editorial Team, "Kp Calculator — Equilibrium Constant in Partial Pressures," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/hi/calculator/kp-calculator
@misc{wecalculate_kp_calculator, title = {Kp Calculator — Equilibrium Constant in Partial Pressures}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/hi/calculator/kp-calculator}}, year = {2026}, note = {TG we-Calculate} }
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