Question

X-ray diffraction studies show that copper crystallises is an fcc unit cell with cell edge of 3.608×10-8 cm .in a separate experiment cell is determined to have a density of 8.92 g/cm3 calculate the atomic mass of cu​

Answer 1

Given :

Side length of the unit cell = 3.608×10⁻⁸ cm

Density of the unit cell = 8.92 g/cm³

To Find :

The atomic mass of copper

Solution :

• In FCC lattice the number of atoms present in one unit cell = 4

• The atomic mass of the element is given by the relation

                      $M=\frac{dN_{A}a^{3} }{z}$

• By substituting the values in the above relation,

                      $M=\frac{8.92\times6.023\times 10^{23}(3.608\times10^{-8})^{3} }{4}$

                      $M=63.1 g/mol$

 The atomic mass of copper is 63.1 g/mol.

Answer 2

${\huge{\underline{\underline{\mathcal{\red{♡ANSWER♡}}}}}}$.

• ❤..In case of ${fcc}$ lattice,number of atoms per unit cell, ${Z=4 atoms}$
• ❤.. Therefore,${M}$ =$\frac{dNA a^3}{z}$
• ❤..${8.92gcm^-3×6.022×10^23 atoms mol^-1×(3.608×10^-8cm)^3}{4 atoms}$
• ❤..${63.1g/mol}$
• ❤..${Atomic mass of copper = 63.1u}$.