Question

Copper crystallises into a fcc lattice with edge length $3.61\times {10}^{-8}cm.$ Show that the calculated density is in agreement with its measured value of $8.92gc{m}^{-3}$

Answer 1

$d=\frac{Z\times M}{a^3\times N_A}$
For fcc lattice of copper, Z = 4
Atomic mass of copper, $M=63.5gmo{l}^{-1}$
$\therefore d=\frac{4\times 63.5gmo{l}^{-1}}{(3.61\times {10}^{-8cm}{)}^3\times (6.022\times {10}^{23}mo{l}^{-1})}=8.97gc{m}^{-3}$
The above calculated value of density is approximately in agreement with its measured value of $8.92c{m}^{-3}$