Question

The equivalent weight of $Zn{\left( {OH} \right)_2}$​ in the following reaction is equal to its :
$[Zn{(OH)_2} + HN{O_3} \to Zn(OH)(N{O_3}) + {H_2}O]$
A.$\dfrac{{formula\;wt.}}{2}$
B.$\dfrac{{formula\;wt.}}{1}$
C.$3 \times formula\;wt.$
D.$2 \times formula\;wt.$

Answer 1

Equivalent weight (which is otherwise called gram comparable) is denoted by E and is defined by the mass of one identical that is the mass of a given substance which combines with or displaces a fixed amount of some other substance. The equivalent weight of a component is the mass which consolidates with or dislodges $1.008{\text{ }}gram$ of hydrogen or $35.5{\text{ }}grams$ of chlorine or $8.0{\text{ }}grams$ of oxygen.

Complete step by step answer:
For a redox equivalent reaction, where a similar compound goes through decrease and oxidation all the while, the $n - factor$ assumes a critical job in deciding the equivalent weight of the compound going through redox response.
The equivalent weight of a compound can be determined by separating the sub-atomic mass by the quantity of positive or negative electrical charges that result from the disintegration of the compound.
The numerical formula of $Eq.{\text{ }}weight$ is given by:
$Equivalent{\text{ }}weight{\text{ }} = {\text{ }}E = \dfrac{{{M_w}}}{n}$
Where, ${M_w} =$Molecular weight
$n =$ $n - factor$ or valency or the quantity of electrons moved.
Equivalent weight, $E = {\text{ }}\dfrac{{Formula{\text{ }}weight}}{{n - factor}}.$
The reaction of Zinc hydroxide with nitric acid produces zinc hydroxide nitrate with the release of water molecules. Now we have the reaction as follows:
$Zn{(OH)_2} + HN{O_3} \to Zn(OH)(N{O_3}) + {H_2}O.\;$
Here the $Zn{\left( {OH} \right)_2}$discharges solo $O{H^ - }$ion in the reaction.
so $n -$factor is$1$.
So, equivalent weight of Zn{\left( {OH} \right)_2}$$$$ = \dfrac{{Formula{\text{ }}weight}}{{n - factor}} = \dfrac{{Formula{\text{ }}weight}}{1}.
Therefore, the correct option is B. $\dfrac{{formula\;wt}}{1}$.​

Note:
The practice of equivalent weights in overall chemistry has mostly been outdated by the practice of molar masses. Equivalent weights might be estimated from molar masses if the chemistry of the matter is well identified.
In $acid - base$ reactions, the equivalent weight of an acid $/$ base is the mass of which provisions or responds through a single mole of hydrogen cations (${H^ + }$). For redox reactions, the equivalent weight of individually reactant provisions or reacts with a single mole of electrons (${e^ - }$) in a redox reaction.