PCl5 acts as an oxidizing agent. Justify.

• PCl5 can only act as an oxidizing agent.

The highest oxidation state of P is +5. In PCl5, phosphorus is in its highest oxidation state (+5). Hence, it can only decrease its oxidation state and act as an oxidizing agent rather than increase in oxidation state and act as a reducing agent.

PCl₅ + H₂→ PCl₃ + 2HCl

In above equation,

In PCl₅, P has oxidation state = 5.

In H₂, H has oxidation state = 0.

In PCl₃, P has oxidation state = 3.

In HCl, H has oxidation state = +1.

Now, taking the other reaction,

2Ag + PCl₅→ 2AgCl + PCl₃.

In Ag, Ag has 0 oxidation state.

In PCL₅, P has +5 oxidation state.

In AgCl, Ag has +1 oxidation state.

In PCl₃, P has +3 oxidation state.