Question

The sulfate of calcium has a formula of $\text{CaS}{{\text{O}}_{4}}$. The formula of the sulfate of ammonium will be
(a). $\text{N}{{\text{H}}_{3}}\text{S}{{\text{O}}_{4}}$
(b).${{\text{(NH3)}}_{2}}\text{S}{{\text{O}}_{4}}$
(c). $\text{N}{{\text{H}}_{4}}\text{S}{{\text{O}}_{4}}$
(d). ${{\text{(NH4)}}_{2}}\text{S}{{\text{O}}_{4}}$

Answer 1

Hint: Here the concept of valency of radicals comes into significance. Ammonium has +1 charge whereas sulfate has +2 charge.

Complete step by step answer:
First of all, we should know about what the term ‘Valency’ is. Valency is the combining capacity of an atom or radical.
An ion or radical is an atom or group of atoms of same or different elements that behave as a single unit with a positive or negative ion.
Radicals have their own combining power based on which they form chemical formulae.

Here are the following steps for writing the chemical formulae.
Write the symbol of a basic radical (element with positive valency) to the left hand side and that of the acid radical (element with negative valency) to the right hand side.
Write the valency of each of the respective radicals at the right hand top of its symbol.
Divide the valency by their highest common factor (H.C.F.), if any, to get the simple ratio. Ignore (+) or (−) symbols of the radicals.
Cross the reduced valencies. If 1 appears, then ignore it. If a group of atoms receives a valency more than 1, then enclose it within brackets.

For Example: $\text{N}{{\text{H}}_{4}}^{+}$ has valency 1 and $\text{S}{{\text{O}}_{4}}^{2-}$ has valency 2.
Hence, the chemical formula is ${{\text{(N}{{\text{H}}_{4}})}_{2}}\text{S}{{\text{O}}_{4}}$.
Therefore, the correct answer is option (d). ${{\text{(N}{{\text{H}}_{4}})}_{2}}\text{S}{{\text{O}}_{4}}$

Note: The molecular formula of a compound has quantitative significance. It represents the respective numbers of different atoms present in one molecule of a compound.