Question

Consider the reaction.

PCl5(g)−⇀PCl3(g)+Cl2(g)Kc=0.0420

The concentrations of the products at equilibrium are [PCl3]=0.170 M and [Cl2]=0.190 M . What is the concentration of the reactant, PCl5 , at equilibrium?

Answer 1

Equilibrium concentration of PCl₃= 0.170 M

Equilibrium concentration of Cl₂= 0.190 M

The equilibrium constant for the reaction K_c= 0.0420

The equation relating the equilibrium constant to the equilibrium concentrations of the reactants and products is:

$Kc=\frac{PCl3\times Cl2}{PCl5}$

$0.0420=\frac{0.170\times0.190}{PCl5}$

$PCl5=\frac{0.0420}{0.0323}$

PCl₅=1.3000