Question

The density of a face-centred cubic element (atomic
mass = 60.2) is 6.25 g cm. Calculate the length of
the edge of the unit cell.
Answer should be in CENTIMETERS ONLY ​

Answer 1

Answer:

There are 4 atoms per unit cell of lattice

Density = mass / volume

         = 4* mass of each atom/ a3 , where a side of cubic unit cell

         = 4* 60.2 * 1.66 * 10 -24 / a3       as atomic mass = 1.66* 10 -24  g

         = 6.25 g/cm3 given

so a3 =  4*60.2 * 1.66 *10-24 / 6.25 cm3

Gives a3 = 6.39 * 10 -23 cm3 = = 63.9* 10 -24

Find a from here

a = 3.93x 10 -8 cm

Explanation: