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

Explanation

The oxidation state of P in `PCl_(5)` is +5. P has 5 electrons in its valence shell. Hence, its oxidation state cannot be increased beyond +5 by donating more electrons.
Therefore, `PCl_(5)` cannot act as a reducing agent.
However, its oxidation state can be lowered from +5 to +3. In this case. `PCl_(5)` acts as an oxidising agent. For example, It oxides Ag to AgCl, Sn to `SnCl_(4)` and `H_(2)` to HCI.
1. `2overset(0)Ag+overset(+5)(P)Cl_(5)to2overset(+1)(A)gCl+overset(+3)(P)Cl_(3)`
2. `overset(0)(S)n+2overset(+5)(P)Cl_(5)tooverset(+4)(S)nCl_(4)+2overset(+3)Cl_(3)`
3. `overset(+5)(P)Cl_(5)+overset(0)H_(2)tooverset(+3)PCl_(3)+2overset(+1)HCl`
In the above reactions, the oxidation number of P decreases from +5 to +3, whereas those of Ag and H increases from 0 to +1 and of Sn increases from 0 to +4. Hence, `PCl_(5)` acts as an oxidising agent.