# Sodium crystallizes in a BCC unit cell. Calculate the approximate number of unit cells in 8.6 g of the sodium (atomic mass of Na = 23)

Sodium crystallizes in a BCC unit cell. Calculate the approximate number of unit cells in 8.6 g of the sodium (atomic mass of Na = 23)

Given Values

Type of unit cell = BCC

So, 1 U.C. is made up of = 2 atoms

Atomic Mass of sodium = 23 gm/mol

Weight of sodium = 8.6 gm

Calculations

Number of atoms in 8.6 gm of Sodium

23 gm of Sodium  =  6.02 × 1023 atoms of Sodium

8.6 gm of Sodium = $$\frac{6.02 \times 10^{23} \times 8.6}{23}$$ atoms

Number of U.C. in 8.6 gm of Sodium

2 atoms of Sodium = 1 Unit Cell

$$\frac{6.02 \times 10^{23} \times 8.6}{23}$$ atoms  =  $$\frac{6.02 \times 10^{23} \times 8.6}{23 \times 2}$$ U.C.

Therefore, there are  $$1.125 \times 10^{23}$$ unit cells in 8.6 gm of Sodium.