Question

Strontium (Sr) has the FCC crystal structure, an atomic radius of 0.215 nm, and an atomic weight of 87.62 g/mol. What is its theoretical density?

Answer 1

Answer:Theoretical density =2.576g/cm³

Explanation:

Theoretical density p= (A×n)/Vc ×Av

A= molecular weight

n= effective number of atoms per unit cell

Vc=Volume of unit cell = a³

Av = Avogadro's constant = 6.02×10²³

Given that A= 87.2g/mol

n= 4 (For FCC crystal structure)

Vc= a³

Where a = 2R√2 and R is the atomic radius

R=0.215

a= 2 × 0.215×√2

a= 0.608nm = 0.608×10^-7 cm

Vc= (0.608×10^-7 cm)³

Vc=2.25×10^-22 cm³

P= (87.2 × 4)/

(2.25×10^-22) × (6.02×10²³)

P= 2.576g/cm³

Therefore the theoretical density of strontium is 2.576g/cm³