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 atoms in 0.5 mole of compound
= 0.5 x 6.022 x 10²³
= 3.011 x 10²³
Number of octahedral voids = Number of atoms in close packing
= 3.011 x 10²³
Number of terahedral voids = 2 x No. of atoms in close packing
= 2 x 3.011 x 10²³
= 6.022 x 10²³
Total number of voids = 3.011 x 10²³ + 6.022 x 10²³
= 9.033 x 10²³