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

Explanation

1 Mole of hexagonal packed structure contains 1 mol of octahedral voids and two moles of tetrahedral voids. Therefore, 0.5 moles of hexagonal packed structure contain 0.5 moles of octahedral voids and 1 mole of tetrahedral voids.
No. of tetrahedral voids `= 6.022 xx 10^(23)`
No. of octahedral voids `= ( 1)/( 2) xx ` no. of tetrahedral voids
No. of octahedral voids `= ( 1)/( 2) xx 6.022 xx 10^(23)`
`= 3.011 xx 10^(23)`
Total No. of voids `= ( 6.022 + 3.011 ) xx 10^(23)`
`= 9.033 xx 10^(23)`