Question

An unknown metal is found to have a density of 7.8748g/cm3and to crystallize in a body-centered cubic lattice. The edge of the unit cell is found to be 0.31627nm. Calculate the atomic mass of the metal.

Answer 1

Density $\rho$ = 7.8748 g/cm³

For body centre Z = 2

$\rho$ = Z x M / a³ x N₀

7.8748 = 2 x M / [(0.31627 X 10^-7)³ x 6.02 x 10²³]

M = (7.8748 x( 0.31627 X 10^-7)³ x 6.02 x 10²³)/2 = 0.7498 x 10² g/mol = 74.98 g/mol

Answer 2

each cell=(0.31627*10^-9) - cell V. atomic mass= 7.8748g/cm3* V Cm3/2*6.023*10^23=

7.49957E+14 atoms/mole

Answer 3