Answer to Question #168118 in General Chemistry for Isabelle Kosche

Question

The equilibrium constant for the following reaction is 0.18 at a set temperature. Find the equilibrium concentrations if the initial concentration of PCl₃ is 0.225 mol/L and the initial concentration of Cl₂ is 0.150 mol/L.

PCl_3(g) + Cl_2(g) ⇌ PCl_5(g)

Answer 1

I:. 0.225............0.150.............0

C:... -x....................-x...................+x

E:..(0.225-x).....(0.150-x)...........x

Kc= [PCl₅] / ([PCl₃] [Cl₂]) = x/[(0.225-x)(0.150-x)] = 0.18

The equation 0.18x² - 0.9325x + 0.006075= 0 has x=0.0065 as the feasile solution

[PCl₅] = 0.0065M

[PCl₃] = 0.225 - 0.0065 = 0.2185M

[Cl₂] = (0.150 -0.0065) = 0.1435M