Question

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

Answer 1

Number of atoms in 1 mole of compound = 6.022 x 10²³

Number of atoms in 0.5 mol = 0.5 x 6.022 x 10²³

= 3.011 x 10²³

For a hexagonal closed packed structure,

Number of octahedral voids = number of atoms in the compound

Therefore, the number of octahedral voids =3.011 x 10²³

And

Number of tetrahedral voids = 2 x octahedral voids

= 2 x 3.011 x 10²³

= 6.022 x 10²³

The total number of voids = (6.022 + 3.011) x 10²³

= 9.033 x 10²³