Question

Copper crystallises into a fcc lattice with edge length 3.61 × 10⁻⁸ cm. Show that the calculated density is in agreement with its measured value of 8.92 g cm⁻³. 

Answer 1

Edge length, a = 3.61 x 10⁻⁸ cm
As the lattice is fcc type, the number of atoms per unit cell, z = 4
Atomic mass, M = 63.5 g mol⁻¹
We also know that N_A = 6.022 x 10²³ mol⁻¹ 

Applying the relation:

= 8.97 g cm⁻³
The measured value of density is given as 8.92 g cm⁻³. 

Hence, the calculated density 8.97 g cm⁻³ is in agreement with its measured value.