Question

calculate the density of Pbs crystal fcc if the edge length of unit cell is 500pm

Answer 1

Answer:

The density of PbS is $12.7 g/cm^3$.

Explanation:

Edge length = 500 pm

Z, for FCC = 4

Molar mass of PbS = 239 g/mol

Density of the crystal lattice is given by the formula:

$\rho=\frac{Z\times M}{N_A\times a^3}$

where,

Z = number of atoms in crystal lattice

M = Molar mass

a = Edge length of the crystal

$\rho=\frac{4\times 239 g/mol}{6.022\times 10^{23}\times mol^{-1}\times (500\times 10^{-10} cm)^3}=12.7 g/cm^3$

The density of PbS is $12.7 g/cm^3$.