The Kp Calculator is an essential tool that allows users to calculate the equilibrium constant in terms of partial pressures (Kp) for gas-phase chemical reactions. By entering the partial pressures of reactants and products along with their stoichiometry, the calculator provides quick, accurate, and reliable results. This is particularly useful for chemistry students, researchers, and industrial chemists who need precise calculations for reaction behavior at equilibrium.
Kp, or the equilibrium constant in terms of partial pressures, measures how far a gas-phase reaction proceeds before reaching equilibrium. For a general reaction:
aA(g) + bB(g) ⇌ cC(g) + dD(g)
The equilibrium constant Kp is expressed as:
K
p
= (P
C
)
c
(P
D
)
d
/ (P
A
)
a
(P
B
)
b
Where:
P
X
= partial pressure of species X in atm
a, b, c, d = stoichiometric coefficients
It can also be related to Kc (concentration-based equilibrium constant) by:
K
p
= K
c
(RT)
Δn
Where Δn = (c + d) − (a + b), R = 0.0821 L·atm/(mol·K), and T = temperature in Kelvin.
1. Kp from partial pressures:
K
p
= (P
C
)
c
(P
D
)
d
/ (P
A
)
a
(P
B
)
b
2. Relation to Kc:
K
p
= K
c
(RT)
Δn
3. Δn definition:
Δn = moles of gaseous products − moles of gaseous reactants
All formulas are highlighted in a frame for easy reference and improved user experience.Reaction:
N
2
(g) + 3H
2
(g) ⇌ 2NH
3
(g)
Given:
P
N
2
= 2 atm, P
H
2
= 6 atm, P
NH
3
= 1 atm
Step 1: Apply Kp formula:
K
p
= (P
NH
3
)
2
/ (P
N
2
)(P
H
2
)
3
Step 2: Substitute values:
K
p
= 1
2
/ (2 · 6
3
) = 1 / (2 · 216) = 1 / 432 ≈ 0.00231
Step 3: Result:
K
p
≈ 0.0023