Question

Give a reason for the following:
-$PC{l_5}$ acts as an oxidizing agent.
-Dinitrogen is chemically inert.

Answer 1

Oxidizing agent: It is a molecule or compound which gains electrons to get reduced itself and oxidizes the other reactant present in a chemical reaction. These are important in industrial use because of their use in processes like bleaching, purifying, etc.

Complete answer:
$PC{l_5}$ acts as an oxidizing agent:
We need to check the oxidation state of phosphorus in the given compound before categorizing it as an oxidizing or a reducing agent. Let the oxidation state of phosphorus be $x$ and the formal charge on chlorine atoms is $( - 1)$.
Therefore,
$x - 5 = 0$
$\therefore x = + 5$
Oxidation state of phosphorus in $PC{l_5}$ is $+ 5$.
We know that phosphorus atoms can only exist in two oxidation states i.e., $+ 3$ and $+ 5$. But in $PC{l_5}$, the phosphorus atom is already at its highest oxidation state which means it cannot donate electrons. So, it cannot act as a reducing agent.
Although it can accept electrons to change its oxidation state from $+ 5$ to $+ 3$ and get reduced during a chemical reaction. Hence, $PC{l_5}$ acts as an oxidizing agent.
Dinitrogen is chemically inert:
In nitrogen atoms, there are five electrons present in the outermost valence shell and hence nitrogen is trivalent for most of its compound. In dinitrogen molecules, there exists a triple bond between two nitrogen atoms $(N \equiv N)$ and the energy required to break this bond is very high because of strong $p - p$ overlapping of orbitals. Therefore, it does not show any reaction at room temperature and hence it is chemically inert.

Note:
The intensity of covalent bonding directly varies with the extent of overlap and the degree of overlap which relates it to the directional nature of the orbitals. Because $p - p$orbital overlap has more directional nature than that of $s - p$ and $s - s$. Therefore, $p - p$orbital overlap is the strongest overlapping.