Can `PCl_(5)` act as oxidising as well as reducing agent ? Justify.

Explanation

The oxidation state of P in `PCl_(5)` is +5. Since P has five electrons in its valence shell, therefore, it cannot increase its oxidation state beyond +5 by donating electrons, therefore, `PCl_(5)` cannot act as a reducing agent. However, it can decrease its oxidation number from +5 to +3 or some lower value, therefore, `PCl_(5)` acts as an oxidising agent. For example, it oxidises Ag to AgCl, Sn to `SnCl_(4) and H_(2)` to HCl.
`2overset(0)(Ag)+overset(+5)(PCl_(5))rarr 2overset(+1)(AgCl)+overset(+3)(PCl_(3))" ," overset(0)(Sn) + 2overset(+5)(PCl_(5)) rarr overset(+4)(SnCl_(4))+2overset(+3)(PCl_(3))`
`overset(+5)(PCl_(5))+overset(0)(H_(2))rarr overset(+3)(PCl_(3))+2overset(+1)(HCl)`
In these reactions, oxidation number of P decreases from +5 in `PCl_(5)` to +3 in `PCl_(3)` and that of Ag and H increases from 0 to +1 and that of Sn from 0 to +4. Thus, `PCl_(5)` acts as an oxidising agent.