Question

An $fcc$ lattice has a lattice parameter $a=400pm$. Calculate the molar volume of the lattice including all the empty space.

• A. 10.8 mL
• B. 96 mL
• C. 8.6 mL
• D. 9.6 mL

Answer 1

Answer: (D)

Number of atoms $=N_A$
$\Rightarrow$ Number of unit cells $=\frac{N_A}{4}$
$[\because 4$ atoms in each unit cell $]$
Volume of $1mol$ lattice $=\frac{N_A}{4}\times$ Volume of unit cell
$=\frac{6.023\times 10^{23}}{4}\times {\left(400\times 10^{-12}\right)}^3{m}^3=9.64mL$