Question

The equivalent weight of nitrobenzene in the reaction: \[{C_6}{H_5}N{O_2}{\text{ }} \to {\text{ }}{C_6}{H_5}N{H_2}\] is:
(A) \[M\]
(B) \[\dfrac{M}{2}\]
(C) \[\dfrac{M}{4}\]
(D) \[\dfrac{M}{6}\]

Answer 1

Hint: Equivalent weight is defined as the mass of one equivalent, i.e., the mass of a substance that will combine or displace a fixed quantity of another substance.

Formula used: The equivalent weight of nitrobenzene in the reaction \[{C_6}{H_5}N{O_2}{\text{ }} \to {\text{ }}{C_6}{H_5}N{H_2}\] is calculated as –
\[Equivalentweight = \dfrac{{Weight{\text{ }}of{\text{ }}formula}}{{valency{\text{ }}of{\text{ }}metal{\text{ }}ion}}\]

Complete step by step answer:
Nitrobenzene \[{C_6}{H_5}N{O_2}\] is a salt that is a yellowish and oily aromatic nitro-compound that has an almond like odour. Upon combustion of \[{C_6}{H_5}N{O_2}\]toxic fumes of nitrogen oxides are produced. The main use of nitrobenzene (\[{C_6}{H_5}N{O_2}\]) is used in the manufacture of aniline, oils, dyes, pesticides and synthetic rubber.
The reaction \[{C_6}{H_5}N{O_2}{\text{ }} \to {\text{ }}{C_6}{H_5}N{H_2}\] is the preparation of aniline. Aniline is an organic compound that is made up of a phenyl group attached to an amino group. It has an odour of rotten fish. It is used in the production of various chemicals.
Equivalent weight of nitrobenzene is calculated by dividing weight of nitrobenzene and its valency.
Here, the weight of nitrobenzene \[{C_6}{H_5}N{O_2}\] is given as \[{\text{M}}\] and the valency is 6 as the reduction of one molecule of nitrobenzene to aniline requires 6 atoms of hydrogen.
Therefore, equivalent weight \[ = {\text{ }}\dfrac{{Weight{\text{ }}of{\text{ }}formula}}{{valency{\text{ }}of{\text{ }}metal{\text{ }}ion}}{\text{ }} = {\text{ }}\dfrac{M}{6}\]

Hence, the correct answer is (D) i.e., \[\dfrac{M}{6}\]

Note: A student can get confused between equivalent weight and equivalent mass. Both of these are methods to measure matter but are slightly different than each other. Equivalent weight is basically a measure of mass proportion of a given element, ion or compound in which it combines with the mass of the other given chemical entities. While on the other hand, Mass of a one-gram equivalent, like its mole counterpart, is equal to mass in grams, which is numerically equal to equivalent weight.