Question

Tungsten has bcc lattice. each edge of the unit cell is 316 pm and density of the metal is 19.35 g/cm³. how many atoms are present in 50 g of the element?

Answer 1

Volume of a uni cell = a3 = (316*10-12) = 31.55*10-30; volume of chromium = mass / density = 50 / 1000*19.35*1000 = 2.58*10-6m3; number of cell units = 2.58*10-6m3 / 31.55*10-30 = 8.19*1022 .

However, there are two atmos for for one unit cell,therefore total number of atoms are = 2*8.19*1022 = 1.63*1023 atoms

Answer 2

$\huge \tt 1.63 \times {10}^{23}$ atoms