Chemistry - Mole Concept Question with Solution | TestHub

Explain the question : Find actual molecule volume in 1L steam.

Concept : This question is based on density $\left(\mathrm{d}=\frac{\mathrm{m}}{\mathrm{V}}\right)\&$ conservation of mass.

Solution : First, calculate the mass of water present in $1\mathrm{L}\left(1000{\mathrm{cm}}^3\right)$ of steam using the vapour density: Mass $=$ volume ${}_{\text{steam }}\times$ density ${}_{\text{steam }}=1000{\mathrm{cm}}^3\times 0.0006\mathrm{g}/{\mathrm{cm}}^3=0.6\mathrm{g}$. This 0.6 is the actual mass of the water molecules. The volume occupied by the molecules themselves (their packed, incompressible volume) is found using the density of liquid water:

Volume ${}_{\text{molecules }}=\frac{\text{ Mass }}{{\text{ Density }}_{\text{liquid }}}=\frac{0.6\mathrm{g}}{1.0\mathrm{g}/{\mathrm{cm}}^3}=0.6{\mathrm{cm}}^3$.

Final answer : C