Question

At $100^{\circ} \,C$, copper $(Cu)$ has $FCC$ unit cell structure with cell edge length of $x\, ?$ What is the approximate density of $Cu$ (in $g\, cm^{-3})$ at this temperature ? [Atomic Mass of $Cu = 63.55\,u]$

• A. $\frac{105}{x^3}$
• B. $\frac{211}{x^3}$
• C. $\frac{205}{x^3}$
• D. $\frac{422}{x^3}$

Answer 1

Answer: (D)

$\frac{422}{x^3}$

Answer 2

FCC unit cell $Z = 4$
$d = \frac{63.5 \times4}{6 \times10^{23} \times x^{3} \times10^{-24}} g/cm^{3}$
$d = \frac{63.5\times4 \times10}{6} g/cm^{3}$
$d = \frac{423.33}{x^{3}} \simeq \left(\frac{422}{x^{3}}\right)$