Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: PCl₅(g) ⇌ PCl₃(g) + Cl₂(g)
At 250° 0.250 M PCl₅ is added to the flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

Question

Quizplus · Accepted Answer

Given $K_c = 1.80$ and initial $[PCl_5] = 0.250 M$, at equilibrium, let $x$ be the amount of $PCl_5$ that decomposes. Thus, $[PCl_5] = 0.250 - x$, $[PCl_3] = x$, and $[Cl_2] = x$. The equilibrium expression is $K_c = \frac{[PCl_3][Cl_2]}{[PCl_5]}$. Solving for $x$ using $K_c = 1.80$ leads to the equilibrium concentrations given in option A.

Phosphorus Pentachloride Decomposes to Phosphorus Trichloride at High Temperatures According