Iron crystallises in a cubic close-packed (ccp) structure. How many voids or holes are there in 0.1 mol of iron?

Explanation

In a ccp structure of particles, number of octahedral voids = number of packed particles and number of tetrahedral voids = 2 `xx` number of packed particles.
0.1 mol of Fe contains `0.1xx6.022xx10^(23)=6.022xx10^(22)` Fe-atoms.
`therefore" "` Number of octahedral voids = Number of packed Fe-atoms = `6.023xx10^(22)` and the number of tetrahedral voids = 2 `xx` number of packed Fe-atoms = `2xx6.022xx10^(22)`.
`therefore" "` Total number of voids in 0.1 mol Fe
`=6.022xx10^(22)+2xx6.022xx10^(22)=1.8066xx10^(23)`