Question

A compound forms hexagonal close-packed structure. What is the total number of voids in $0.5$ mol of it? How many of these are tetrahedral voids?

Answer 1

Number of tetrahedral voids in $1$ unit cell $HCP=12$

Number of octahedral voids in $1$ unit cell $HCP=6$

Total voids in $1$ unit cell $HCP=18$

Total voids in $1$ unit cell $HCP=18$

Total number of voids in $0.5molHCP=18\times \frac{1}{2}\times 6.02\times {10}^{23}=5.4\times {10}^{24}voids$

Total number of tetrahedral voids in $0.5molHCP=12\times \frac{1}{2}\times 6.02\times {10}^{23}=3.612\times {10}^{24}voids$