The density of solid Cr is 7.15 g/cm3. How many atoms are present per cubic centimeter of Cr?

As a solid, Cr adopts a body-centered cubic unit cell. How many unit cells are present per cubic centimeter of Cr?

For a body centered cubic unit cell, it is known that there will be two atoms per unit cell. For the number of unit cells per cubic centimeter, we do as follows:

(7.15g / 1 cm³) x (1 mol / 52.00g) x (6.022x10^23 atoms / 1 mole) x (1 unit cell / 2 atoms) = 4.14 x 10^22 units cells / cm^3

Hope this answers the question. Have a nice day.