Question

How to calculate the equivalent weight of copper sulphate?

Answer 1

Hint: We have to know that the equivalent weight of a compound is the molecular weight of the compound per number of equivalent molecules of it. We can write the formula of equivalent weight of compound as,
${\text{Equivalent weight}} = \dfrac{{{\text{Molecular weight}}}}{{{\text{No}}{\text{. of equivalent moles}}}}$

Complete answer:
We have to know that the equivalent weight of an element is similar to the atomic mass (or) molecular weight by the valence number. We have to know that the valence number is also known as n-factor (or) the amount of equivalent moles. We have to know that the value of the valence number is based on the type of reaction that takes place.
We can write the expression for calculating the equivalent weight as,
${\text{Equivalent weight}} = \dfrac{{{\text{Molecular weight}}}}{{{\text{No}}{\text{. of equivalent moles}}}}$
We know that the molecular weight of copper sulfate is $160g/mol$.
Let us now determine the valence factor of copper sulfate. We have to know that the valence factor is nothing but the number of electrons gained (or) lost by chemical species. In copper sulfate, two electrons of copper are lost and its charge becomes $ + 2$. So, the valence factor of copper is $ + 2$. Similarly, two electrons are gained by sulfate and its exhibits of charge is $ - 2$. So, the valence factor of copper sulfate is two.
Let us now calculate the equivalent weight by using the molecular weight of copper sulfate and the number of equivalent moles of copper sulfate.
We can calculate the equivalent weight of copper sulphate as,
${\text{Equivalent weight}} = \dfrac{{{\text{Molecular weight}}}}{{{\text{No}}{\text{. of equivalent moles}}}}$
${\text{Equivalent weight}} = \dfrac{{160g/mol}}{{2mol}} = 80g$
So, we have to know that the equivalent weight of copper sulfate is $80g$.

Note:
We have to know that the concept of equivalent weight is used to calculate the atoms combined in a particular amount ratio to give molecules. This means that when particular amounts of elements are combined though there would be variation in the amount they combine in the way that number of atoms is used to calculate the amount of elements gives the mass. So, the equivalent weight of copper sulfate is based on the quantity of electrons.