Question

How do you find the equilibrium constant with pressure?

Answer 1

First, we know about the equilibrium constant,

Equilibrium constant: A number that expresses the relationship between the amounts of products and reactants present at equilibrium in a reversible chemical reaction at a given temperature.

The formula for finding the equilibrium constant with partial pressure

Consider a gas phase reaction,

$\therefore \mathrm{aA}\left(\mathrm{g}\right)+\mathrm{bB}\left(\mathrm{g}\right)\rightleftharpoons \mathrm{cC}\left(\mathrm{g}\right)+\mathrm{dD}\left(\mathrm{g}\right)$, the expression for ${\mathrm{K}}_{\mathrm{p}}$ is

$\Rightarrow {\mathrm{K}}_{\mathrm{p}}=\frac{{\left({\mathrm{P}}_{\mathrm{c}}\right)}^{\mathrm{c}}{\left({\mathrm{P}}_{\mathrm{D}}\right)}^{\mathrm{d}}}{{\left({\mathrm{P}}_{\mathrm{A}}\right)}^{\mathrm{a}}{\left({\mathrm{P}}_{\mathrm{B}}\right)}^{\mathrm{b}}}$

Here the concentration of product is divided by the concentration of reactant.

$\Rightarrow$${\mathrm{K}}_{\mathrm{p}}$ is related to the equilibrium constant in terms of the molar concentration, ${\mathrm{K}}_{\mathrm{c}}$ by the equation below:

$\Rightarrow {\mathrm{K}}_{\mathrm{p}}={\mathrm{K}}_{\mathrm{c}}{\left(\mathrm{RT}\right)}^{∆\mathrm{n}}$

Where $∆\mathrm{n}$:

$\therefore ∆\mathrm{n}=\mathrm{mol}es\mathrm{of}\mathrm{product}\mathrm{gas}-\mathrm{mol}es\mathrm{of}\mathrm{reactant}\mathrm{gas}$