Question

A bcc element (atomic mass 65) has a cell edge of 420 pm. Calculate its density in gms/cm³ .

Answer 1

Density,  `ρ = (ZxxM)/(a^3 xx N_A)`

Given,    Z = 2 (for bcc arrangement )

             M = 65 

              a = 420pm = 420 × 10^-10 cm

            N_A = 6.023 × 10²³

∴            ρ = `(2×65)/((420×10^-10)^3 × 6.023 × 10^23) = (2×65×10^4)/((42)^3 ×6.023)`

                = 2.91 g cm^-3

Density of the given element is 2.91 g cm^-3.