Question

A compound forms cubic close packed structure. What is the total number of tetrahedral voids in $1.2mol$ of it?

• A. $10.83\times {10}^{22}$
• B. $21.68\times {10}^{23}$
• C. $7.22\times {10}^{23}$
• D. $14.45\times {10}^{23}$

Answer 1

The correct option is D $14.45\times {10}^{23}$

In ccp, number of cpp/fcc forming atoms per unit cell = 4
$\therefore N=4$
$\text{Number of tetrahedral voids in fcc lattice}=8$

$\text{Total number of tetrahedral voids per CCP forming atom}=\frac{8}{4}=2$
$\because$ In $1mol$ of compound,
$\text{Total no. of tetrahedral voids}=2\times Avagadronumber=(2\times 6.023\times {10}^{23}$
$\therefore$ In $1.2mol$ compound,
$\text{Total no. of tetrahedral voids}=2\times 1.2\times 6.023\times {10}^{23}=14.45\times {10}^{23}$
Correct option is d)