Question

Total number of voids in $0.45mol$ of a compound forming a hexagonal close packed structure is_______ $\times {10}^{23}.$ (Round off to the nearest integer)

Answer 1

$\text{In HCP, number of atoms per unit cell}=6$

$\text{Number of octahedral voids}=6$

$\text{Number of tetrahedral voids}=2\times 6=12$

$\text{Total number of voids}=6+12=18$

$\text{Total number of voids per atom}=\frac{18}{6}=3$

$\text{Total number of voids in}1mol=3\times 6.023\times {10}^{23}$

$\text{Total number of voids in}0.45mol=0.45\times 3\times 6.023\times {10}^{23}=8.13\times {10}^{23}$

$\text{Total number of voids in}0.45mol\approx 8\times {10}^{23}$