Question

The total number of gram molecules of $S{O_2}C{l_2}$ in $13.5g$ of sulphuryl chloride is:
(A) $0.1$
(B) $0.2$
(C) $0.3$
(D) $0.4$

Answer 1

Hint: Gram molecules can be defined the same as that of a mole. Gram molecules are the total number of molecules in one mole of substance.Gram molecule is defined as the number of grams of a substance that is the same as the relative molecular mass of that substance.

Complete step by step answer:
First of all, let's understand about the chemical compound sulfuryl chloride. It is an inorganic compound with the chemical formula \[S{O_2}C{l_2}\]. It is a colorless liquid with a pungent smell at the room temperature. Sulfur chloride is the source of chlorine gas. The IUPAC name of \[S{O_2}C{l_2}\] is sulfuryl dichloride.
In the question, we have to find the gram molecules of $13.5g$ of \[S{O_2}C{l_2}\]. Gram molecules are the same as molecules. Gram molecules are defined as the number of moles present in the given mass of the substance.
i.e., \[Gram{\text{ }}Molecules = \dfrac{{given{\text{ }}mass{\text{ }}of{\text{ substance}}}}{{molecular{\text{ }}mass{\text{ }}of{\text{ substance}}}}\] …. (i)
The molecular mass of a substance is the average relative mass of its molecules as compared with an atom of carbon $ - 12$ isotope or for a compound, it is defined as the combined atomic mass of all elements present in the compound. So, the molecular mass of \[S{O_2}C{l_2}\] can be calculated as
\[1 \times atomic{\text{ }}mass{\text{ }} of {\text{ }}sulphur + 2 \times atomic{\text{ }}mass{\text{ }}of{\text{ }}oxygen + 2 \times atomic{\text{ }}mass{\text{ }}of{\text{ }}chlorine\]

We know that atomic masses of sulphur, oxygen and chlorine are $32g,16g\& 35.5g$ respectively. Thus, the molecular mass of \[S{O_2}C{l_2}\] becomes = \[1 \times 32 + 2 \times 16 + 2 \times 35.5 = 135g\]
Gram molecules = $\dfrac{{13.5}}{{135}} = 0.1$
Hence, the answer is option (A).

Note:
The molecular mass of a substance expressed in grams is called the gram molecular mass. This amount is also called one gram molecule.The molecular mass (m) is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.