At 500 K, the reaction is at equilibrium with the following concentrations. [PCI5] = 0.0095 M [PCI3] = 0.020 [CI2] = 0.020 M What is the equilibrium constant for the given reaction? 0.042 0.42 2.4 24

Although it is omitted, the reaction equation for the decomposition of phosphorus pentachloride is:

PCl₅ → PCl₃ + Cl₂

The equilibrium constant's equation then becomes:

Kc = [PCl₃]*[Cl₂] / [PCl₅]

Kc = (0.02 * 0.02) / 0.0095

Kc = 0.042

The equilibrium constant is 0.042.