Answer: The equilibrium concentration of [tex]PCl_5[/tex] is 1.285 M.
Explanation:
The chemical equation for the decomposition of phosphorus pentachloride follows:
[tex]PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)[/tex]
The expression for equilibrium constant is given as:
[tex]K_c=\frac{[PCl_3][Cl_2]}{[PCl_5]}[/tex]
We are given:
[tex]K_c=0.042[/tex]
[tex][PCl_3]=0.18M[/tex]
[tex][Cl_2]=0.30M[/tex]
The concentration of solid substances are taken to be 1. Thus, they do not appear in the equilibrium constant expression.
Putting values in above equation, we get:
[tex]0.042=\frac{0.18\times 0.30}{[PCl_5]}[/tex]
[tex][PCl_5]=1.285[/tex]
Hence, the equilibrium concentration of [tex]PCl_5[/tex] is 1.285 M.
