Question

Calculate the molar mass of Sulphur.
A. 356 grams
B. 400 grams
C. 598 grams
D. 256 grams

Answer 1

Hint: The gram-atomic mass of Sulphur is 32 grams. Also, remember that Sulphur exists in nature in the form of a poly-atomic molecule that is ${{S}_{8}}$.

Step-by-Step Solution:
Let us first define what the term molar mass really means so as to ensure that there is no confusion later.
In chemistry, the molar mass is defined as the mass of a sample of that compound divided by the amount of substance in that sample, measured in moles. The molar mass is a bulk, not molecular, property of a substance.
Now, let us remember that Sulphur most commonly exists as a polyatomic allotrope as ${{S}_{8}}$.
Let us now get to measuring the molar mass of Sulphur in particular,
Molar Mass = Gram-Atomic Mass × 8 (As a result of it being a polyatomic molecule)
That implies,
Molar Mass of Sulphur = 32× 8 = 256 grams.
Since, we know that the molar mass of Sulphur is 256 grams, thus we can conclude that the answer to this question is d) 256 grams.

Note: Be extremely careful of the difference between the molar mass and the molecular mass of a chemical compound, since the molecular mass of a compound is simply the mass of one molecule of the compound in question whereas the molar mass of a chemical compound is the mass of an ${{N}_{0}}=6.023\times {{10}^{23}}$molecules.