Question

1. The density of solid Cu is 8.96g/cm3 . How many atoms are present per cubic centimeter(cm3) of Cu ?

Answer 1

Answer:

8.5 × 10²² atom / cm³, 2.125 × 10²² unit cells / cm³, 4.7 × 10⁻²³ cm³ / cell unit, 3.61 × 10⁻⁸ cm /cell

Explanation:

The density of the solid Cu = 8.96 g/cm³

a) number of atoms present

mole = mass / molar mass = (8.96 g/cm³) / 63.546 = 0.141 mol

number of atoms = mole × avogadro's constant = 0.141 × 6.02 × 10²³ = 8.5 × 10²² atom / cm³

b) a face-centered cubic unit cell contains 4 atoms

8.5 × 10²² atom / cm³ / 4 = 2.125 × 10²² unit cells / cm³

c) the volume of a unit cell of the metal = reciprocal of  2.125 × 10²² unit cells / cm³  = 1 ÷ ( 2.125 × 10²² unit cells / cm³ ) = 4.7 × 10⁻²³ cm³ / cell unit

the edge length of a cell of cu = ∛(4.7 × 10⁻²³ cm³ / cell unit) = 3.61 × 10⁻⁸ cm /cell