Question

What is the density of iridium metal? (Ir: 192.2 g/mol; face-centered cubic with 3.83x10^-8 cm edges).

Answer 1

Number of atoms in FCC repeat structure: 5
Mass of one atom of Ir:
192.2 / 6.02 x 10²³
= 1.60 x 10⁻²¹ g

Volume = (3.83 x 10⁻⁸)³ cm³

density = (1.60 x 10⁻²¹ x 5) / (3.83 x 10⁻⁸)³ 
= 28.4 g cm⁻³