Question

For \[0.3g\] of an acid is neutralized by \[40c{{m}^{3}}\] of \[0.125N\text{ }NaOH.\] Equivalent mass of the acid is:
A.$60.$
B.$45.$
C.$30.$
D.$63.$

Answer 1

Hint: We know that in order to find the equivalent weight of a given compound we will use the formula of equivalent weight as it is the ratio of molecular mass to the number of replaceable hydrogen. By the use of a general formula and the atomic masses of elements from the periodic table we will solve this problem.

Complete answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts. Depending on the type of the chemical species under consideration, the formula for calculating the equivalent mass can be varied. The basic formula for calculating the equivalent mass of any chemical species can be done by dividing the sum of the masses of the number of atoms of the given chemical species by the key characteristic property of that species.
Similarly, in the case of acids, it is its acidity and in the case of bases it is their basicity. The acidity of a compound can be explained as the number of replaceable hydrogen atoms in the given molecule of the acid. Similarly, basicity can be explained as the number of replaceable hydroxy groups in the molecular structure.
Number of equivalent of acid \[=\] Number of equivalent of base \[\dfrac{N\times V}{1000}\text{ }=\text{ }\dfrac{0.125\times 40}{1000}\text{ }=\text{ }0.005\]
thus, 0.005 equivalents of acid weight \[=\text{ }0.3\] and one equivalent of acid weight \[=\text{ }\dfrac{0.3}{0.005}\text{ }=\text{ }\dfrac{3}{10}\times \dfrac{1000}{5}\text{ }=\text{ }60g\]
Therefore, \[0.3g\] of an acid is neutralized by \[40c{{m}^{3}}\] of \[0.125N\text{ }NaOH.\] Equivalent mass of the acid is $60g.$

Note:
Remember that Equivalent weight is the weight of one equivalent which is the weight of a given substance which combines with or displaces a fixed quantity of another. An element's equivalent weight is the mass which combines or displaces \[1.008\] grams of hydrogen. The main use of sulfuric acid is in fertilizer production, e.g., lime superphosphate and ammonium sulfate. It is commonly used even in the processing of chemicals and other acids.