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Copper crystallises in fcc unit cell with cell edge length of $3.608\times10^{-8}$ cm. The density of copper is $8.92\ g\ cm^{-3}$. Calculate the atomic mass of copper.
A
65 u
B
63.1 u
C
31.55 u
D
60 u
Detailed Solution
$d = \frac{Z \times M}{N_A \times a^3}$, with Z = 4 for fcc
$8.92 = \frac{4 \times M}{6.022 \times 10^{23} \times (3.608 \times 10^{-8})^3}$
$M = \frac{8.92 \times 6.022 \times 10^{23} \times 46.96 \times 10^{-24}}{4} = 63.1$ g/mol
Atomic mass of copper = 63.1 u