Iron has a body centred cubic unit cell with a cell dimension of `286.65` pm. The density of irong is `7.874 g cm^(-3)`. Use this information to calculate Avogardo's number ?

Answer

`6.022 xx 10^(23)`

Explanation

Density, `rho = (Z xx M)/(a^3 xx N_A)`
`a = 286.65 xx 10^(-10) cm, Z = 2 ` (for bcc)
`M = 55.845 u, rho = 7.874 g cm^(-3)`
`7.874 xx (2 xx 55.845)/((286.65 xx 10^(-10))^(3) xx N_A)`
or `N_A = (2 xx 55.845)/((286.65 xx 10^(-10))^(3) xx 7.874) = 6.022 xx 10^(23)`.