Question

What weight of a metal of equivalent weight $12$ will give $0.475g$ of its chloride?
A.$0.12g$
B.$0.24g$
C.$0.36g$
D.$0.48g$

Answer 1

Equivalent weight of an element or compound is the amount of a substance that completely combines or reacts with other substances in the reaction. Equivalent weight of a compound depends upon two factors, molar mass and the valency of the compound.

Complete answer:
Equivalent weight is very commonly used in physical chemistry. It is used in calculation of Normality which is a measure of Concentration. Equivalent weight is calculated by dividing the molar mass of the compound with valency of the compound.
$\Rightarrow$ ${E_w} = \dfrac{M}{x}$
Where ${E_w}$ is the equivalent weight, M is the molar mass and x is the valency of the compound.
Let us assume that the weight of the metal is ${W_m}$. Equivalent weight of metal is given and equivalent weight of Chlorine is $35.5$. calculating the Equivalent weight of the metal chloride
$\Rightarrow$ $E = 12 + 35.5$
we get the equivalent of metal chloride
$\Rightarrow$ $E = 47.5g$
Let us write the given values
Equivalent weight of the metal, ${E_m} = 12g$
Weight of metal chloride, $W = 0.475g$
for calculating the weight of the metal, we will use the expression
$\Rightarrow$ $\dfrac{{{E_m}}}{E} = \dfrac{{{W_m}}}{W}$
Substituting the values of Equivalent weight of metal, Equivalent weight of metal chloride and Weight of the metal chloride we get the equation
$\Rightarrow$ ${W_m} = \dfrac{{12 \times 0.475}}{{47.5}}$
The value of weight of the metal is
$\Rightarrow$ ${W_m} = 0.12g$
So, the right answer is option (A).

Note:
Valency of different compounds is calculated differently, for acids the valency is given by their basicity, for bases the valency is given by their acidity. The valency of the metal salts is given by the charge on the cation in the compound.