Question

How many moles of sulfur are in 80 grams of sulfur?

Answer 1

The mole is defined as the amount of substance which is generally expressed in the terms of weight, volume and number of particles. The one mole of a substance contains the fixed number of particles which are present in 12g of the Carbon-12 atoms. The moles of the substance is calculated by dividing the given mass by its molecular mass.

Complete step by step answer:
We can calculate the number of moles present in the substance by the following formula, the formula is:
Moles= $\dfrac{{mass}}{{molecular \; mass}}$
So we can easily calculate the number of moles by dividing the mass or we can say the given mass by the substance molecular mass. So now we should write the values which are given in the question itself. The question says that we need to calculate the moles in 80g of sulfur.
The given mass = 80grams. We know that the molecular mass of sulfur (${S_8}$)will be the product of the atoms present and its atomic mass. So,
The atomic mass of sulfur = 32grams$mo{l^{ - 1}}$
The molecular mass for 8 atoms of sulfur = $32 \times 8$=256grams$mo{l^{ - 1}}$
Now substituting the values in the formula we get,
Moles = $\dfrac{{80}}{{256}}$ = 0.3125 moles

So the number of moles present in 80grams of sulfur is 0.3125 moles.

Note: If the question asked to calculate the number of atoms then after calculating the number of moles we would have multiplied it with the Avogadro number. If the question has given us the volume instead of mass and we have to calculate the number of atoms then we would have divided the given volume by 22.4L to calculate the number of moles then multiplied it with the Avogadro number. The avogadro number is equal to the $6.023 \times {10^{23}}$.