Kp And Kc
Kp And Kc are the equilibrium constant of an ideal gaseous mixture. Kp is equilibrium constant used when equilibrium concentrations are expressed in atmospheric pressure and Kc is equilibrium constant used when equilibrium concentrations are expressed in molarity.
For many general chemical reactions aA + bB ⇋ cC + dD
Where a mole of reactant A
b mole of reactant B
c mole of product C
d mole of product D
Consider an example
2A(g)+B(g) ⇋ 2C(g) All in the gas phase.
The Kp is given by-
Ideal Gas Equation
Each of these ideal gas molecules behaves similarly. So for each of them,
PV = nRT
On rearranging we get-
Substituting these in equation (1)
On cancelling like terms and substituting
Or
In general,
\(\begin{array}{l}K_{p}=K_{c}\left ( RT \right )^{\Delta n}\end{array} \) |
Where, Δn represents the change in the number of moles of gas molecules. [That is Δn = product – reactant in moles only for gas molecules]
When the change in the number of moles of gas molecules is zero, that is Δn = 0
⇒ Kp=Kc
In general, for any chemical reactions of gas molecules the relation between Kp And Kc is-
\(\begin{array}{l}K_{p}=K_{c}\left ( RT \right )^{\Delta n}\end{array} \) |
\(\begin{array}{l}K_{c}=K_{p}\left ( RT \right )^{-\Delta n}\end{array} \) |
Physics Related Topics:
| Unit of pressure |
| Boyle’s law |
| Ideal gas laws at absolute zero |
Frequently Asked Questions – FAQs
What are the basic properties of gases?
Gases are very easy to compress. They occupy more space than solids or liquids.
They typically expand to fill the spaces around them.
What is the ideal gas equation?
What is pressure?
What is temperature?
What is an ideal gas?
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