Question

Equivalent weight of $C{O_3}^{2 - }$ is:
A. $60$
B. $30$
C. $45$
D. $40$

Answer 1

Hint: To find equivalent weight, firstly molecular weight must be known and then it can be calculated very easily. So we need to calculate molecular weight of $C{O_3}^{2 - }$ and with the help of this answer can be determined.

Complete step by step answer :
Now, to calculate equivalent weight, we need molecular weight first.
Molecular weight of $C{O_3}^{2 - }$ is $60$ as we know.
Equivalent weight is calculated by dividing the molecular weight by a factor $n$ .
\[\text{Equivalent weight} = \dfrac{{\text{Molecular weight}}}{n}\]
Here, $n$ = acidity (for bases)
$n$ = basicity (for acids)
$n$ = valency (for elements)
$n$ = cationic charge (for compounds)
$n$ = charge for charged species
Now for $C{O_3}^{2 - }$
It has charge = $ - 2$
By applying in the formula, we get
\[\text{Equivalent weight} = \dfrac{{60}}{2}\]
\[ \text{Equivalent weight} = 30\]
Hence, Equivalent weight of $C{O_3}^{2 - }$ is $30g$

So the correct option is B.

Additional Information:
The equivalent weight of an element is equal to the atomic weight or can be said formula weight divided by the valence which is assumed in compounds. The unit is the atomic mass unit for equivalent weight, the amount of a substance calculated in grams which is numerically equal to the equivalent weight is known as gram equivalent.
Equivalent weight not similar to molecular weight is proportional to mass of chemical entities which actually combine or displace various other chemical entities. It is stated as the mass of an element or compound or ion which combines or displaces one part of hydrogen or eight parts of oxygen
The idea of comparing equivalent mass with chemically different elements, Atoms actually combine with each other in forming chemical compounds, like that the elements are always present there in definite proportions by mass and this property is useful in making chemically different molecules having different mass.
$C{O_3}^{2 - }$ is carbonate. A carbonate is generally a salt of carbonic acid, which is characterized by the existence of the carbonate ion, a polyatomic ion having the chemical formula of $C{O_3}^{2 - }$ .

Note: Equivalent weight can only be found by knowing the molecular weight and the charge of the compound particularly for this question. So firstly, by finding the molecular weight then by charge on the compound, the answer can be determined.