Dissociation of Phosphorus Pentachloride decreases with increasing pressure

At constant temperature, the dissociation of Phosphorus Pentachloride decreases with increasing pressure.

The reaction: PCl₅↔ PCl₃ + CO₂

no. of moles →  1          1          1

At constant temperature, the effect of pressure change depends on a number of moles of reactant and product. In this reaction the number of moles produces is higher than reactant. For that, the dissociation decreases with increasing pressure.