# Calculate the number of molecules of sulphur

Question.
Calculate the number of molecules of sulphur $\left(\mathrm{S}_{8}\right)$ present in $16 \mathrm{~g}$ of solid sulphur.

Solution:

1 mole of solid sulphur $\left(\mathrm{S}_{\mathrm{o}}\right)=8 \times 32 \mathrm{~g}=256 \mathrm{~g}$

i.e., $256 \mathrm{~g}$ of solid sulphur contains $=6.022 \times 10^{23}$ molecules

Then, $1 \mathrm{~g}$ of solid sulphur contains $=\frac{6.02 \times 10^{23}}{256}$

$16 \mathrm{~g}$ of solid sulphur contains $=\frac{6.02 \times 10^{23} \times 16}{256}$

$=3.76 \times 10^{22}$ molecules (approx)