Question

What is the molar mass of a sulphur molecule?

Answer 1

The molar mass of sulphur molecules can be found by determining the most stable molecule formed by sulphur atoms. Sulphur can combine to form two, four, six and eight membered rings or open chains but the most stable molecule needs to be used for molar mass calculation.

Complete answer:
The molar mass of any molecule is a measure of the total matter contained by one mole of that chemical species.
Sulphur is a non-metallic element belonging to the oxygen family i.e. it is the second member of the sixteenth group of the modern periodic table. Sulphur has lesser electronegativity as compared to oxygen and also has vacant d-orbitals available due to which it can extend its valency.
Sulphur has six electrons in its outermost valence shell and usually accepts two electrons from electropositive elements. Oxygen exists as a diatomic molecule in which it is covalently bonded to another oxygen atom. Thus oxygen gas consists of two oxygen atoms linked to each other through double bonds.
Unlike oxygen, sulphur does not form stable double bonds with itself and prefers single bond formation. Thus the most stable form in which sulphur exists is a molecule containing eight sulphur atoms connected to each other through single covalent bonds and the formula of the molecule is ${S_8}$.
The formula for calculating the molar mass of a molecule is:
${\text{molar mass}} = {\text{(molar mass of element)}} \times {\text{(number of atoms)}}$
The molar mass of sulphur as an element is $32gmo{l^{ - 1}}$ and there are eight sulphur atoms in a molecule
${\text{molar mass of }}{S_8} = {\text{(}}32gmo{l^{ - 1}}{\text{)}} \times 8 = 256gmo{l^{ - 1}}$
Hence, the molar mass of sulphur molecule is $256gmo{l^{ - 1}}$

Note:
The sulphur molecule having eight atoms is a closed structure that forms a crown-like shape. Each sulphur atom is linked to two other sulphur atoms adjacent to it through single covalent bonds. The octet of each atom is satisfied in this structure.