Question

What will be the mass of 5 moles of $S{O_2} $ ?

Answer 1

Hint :$S{O_2} $ is a triatomic molecule. It is made up of one atom of sulphur and 2 atoms of oxygen.
To find out the molecular mass of any molecule we will have to add the atomic mass of the constituent atoms together.
1 mole of any substance will contain $6.022 \times {10^{23}}{\text{ }} $ atoms or molecules. So to find the mass of 5 moles of $S{O_2} $ , we have to find the mass of one mole first.

Complete Step By Step Answer:
To find the mass of one molecule of $S{O_2} $ we have to add the mass of one atom of sulphur and two atoms of oxygen.
This will give us the molecular weight of $S{O_2} $
Mass of $S{O_2} $ = Mass of ${\text{S }} $ + $2 \times $ Mass of ${\text{O}} $
Since mass of sulphur is 32 ${\text{ g/mol}} $ and mass of oxygen is 16 ${\text{ g/mol}} $
$ \Rightarrow 32 + 2 \times 16 $
$ \Rightarrow 32 + 32 $
$ \Rightarrow 64{\text{ g/mol}} $
The mass of 1 mole of any substance is equal to that substance's molecular weight.
Thus we can say that each mole of $S{O_2} $ weighs 64 grams.
Now we have to find out the mass of 5 moles of $S{O_2} $
Since 1 mole of $S{O_2} $ weighs $64{\text{ g/mol}} $
We can say that 5 moles of $S{O_2} $ weighs
$ \Rightarrow 5{\text{ moles }} \times 64{\text{ g/mol}} $
$ \Rightarrow 320{\text{ grams}} $
Therefore the mass of 5 moles of $S{O_2} $ is 320 grams.

Note :
Since each mole of a substance contain $6.022 \times {10^{23}} $ atoms or molecules or ions, we can say that 1 mole of $S{O_2} $ contains $6.022 \times {10^{23}} $ molecules of sulphur dioxide.
So 5 moles of $S{O_2} $ will contain 5 times the number molecules as in 1 mole of $S{O_2} $
This means that 5 moles of $S{O_2} $ contains
$ \Rightarrow 5 \times 6.022 \times {10^{23}}{\text{ S}}{{\text{O}}_2}{\text{ molecules }} $
$ \Rightarrow 30.11 \times {10^{23}}{\text{ S}}{{\text{O}}_2}{\text{ molecules}} $
While dealing with problems involving moles, always make sure to apply these concepts.