Question

An element with molar mass 27 g/mol forms cubic unit cell with edge length of 405 pm. If density of the element is 2.7 g/cm³, what is the nature of cubic unit cell ? (fcc or ccp)

Answer 1

Given : Molar mass = M = 27 g mol^-1 

Nature of crystal = cubic unit cell

Edge length = a = 405 pm = 4.05 × 10^-8 cm

Density = ρ = 2.7 g cm^-3

Nature of unit cell = ?

Hence the nature of unit cell = face-centred

cubic unit cell

Radius of Al atom = 125 pm

The nature of cubic unit cell is fcc.