Question

# The mass (in g) of $1{\text{ }}mole{\text{ }}of{\text{ }}{O_2}$ is:

Hint: We must know that an oxygen molecule is having two oxygen atoms (covalently bonded), and the mass of one atom is $16{\text{ }}amu$.

Complete step by step solution:
First Of all it is important that we understand the meaning of the term molar mass. Molar mass is the mass of one mole of a substance. For example, the mass of one mole of oxygen will be called its molar mass.
Another thing to note is that one molar mass in grams is equivalent to the molecular mass of the substance.
Now coming to Oxygen, we know that one molecule of oxygen carries 2 atoms of oxygen and one mole of oxygen atom is having mass of 16g so,
Oxygen $(O_2)$$\; = {\text{ }}16 \times 2{\text{ }} = {\text{ }}32g/mol$
Therefore, we can state that one mole of oxygen contains $32g$.
Another way to calculate molar mass is to use the formula mentioned below:
$Mass{\text{ }}of{\text{ }}a{\text{ }}substance = {\text{ }}molar{\text{ }}mass{\text{ }} \times {\text{ }}number{\text{ }}of{\text{ }}moles$
So, we are having molar mass of ${O_2}$equal to $32g$ and number of moles is one, now putting this in the given we get,
Mass of substance $= {\text{ }}32g{\text{ }}X{\text{ }}1{\text{ }} = {\text{ }}32g$

Hence, the mass (in g) of$1{\text{ }}mole{\text{ }}of{\text{ }}{O_2} is {\text{ }}32g$

Note: We can use the mole to calculate the number of elementary entities (usually atoms or molecules) in a certain mass of a given substance. Also we know Avogadro’s number is an absolute number: there are $6.022 \times {10^{23}}$ elementary entities in 1 mole. We can also be written as $6.022 \times {10^{23\;}}mo{l^{ - 1}}$.The mass of one mole of a substance is equal to that substance’s molecular weight.