1 cm = (10 × 10^10)pm Therefore; the unit length of the cell is equivalent to 3.923 × 10^-8 cm The volume of the cubic cell is given by (length)³ = (3.923×10^-8)³ = 6.0375 × 10^-23 cm³ Density is calculated by dividing mass with the volume The atomic mass of platinum 195.064 g/mol , Therefore, The average mass of one atom is; (Avogadro's constant = 6.0×10^23 particles) 195.064 ÷ 6.022 × 10^23 atoms/mol = 3.239 × 10^-22 g/atom The mass of the 4 platinum atoms in the face centered cubic unit cell: (3.239 × 10^-22) × 4 = 129.56× 10^-23 g/unit cell Therefore; Density = (129.56× 10^-23)÷(6.0375 ×10^-23) = 21.459 g/cm³
