K_p= 0.04 atm at 899 K for the equilibrium shown below. What is the equilibrium concentration of C₂H₆ when it is placed in a flask at 4.0 atm pressure and allowed to come to equilibrium?

C₂H₆ (g) ⇌ C₂H₄ (g) + H₂ (g)

For the given reaction, lets assume that p atm is the pressure exerted by ethene and hydrogen gas at equilibrium.

Therefore, the given reaction is:

C₂H₆ (g) ⇌ C₂H₄ (g) + H₂ (g)

Equilibrium pressure constant (K_p) is defined as a number that expresses the relationship between the partial pressures of products and reactants present at equilibrium in a reversible chemical reaction at a given temperature.

Here. K_p= 0.04 atm

For the given reaction,

Where, = partial pressure pf C₂H₄ in atom at equilibrium

= partial pressure of H₂ in atom at equilibrium

= partial pressure of C₂H₆ in atom at equilibrium

p²=0.16-0.04p

p²+0.04p-0.16=0

Now,

(Taking positive value)

p=0.38

Therefore at equilibrium, [C₂H₆]= 4 - p = 4 - 0.38

=3.62 atom