Sodium crystallises in a bcc unit cell. What is the approximate number of unit cells in 4.6 g of sodium? Given that the atomic mass of sodium is 23 g/ mol.
We are given that the sodium crystallizes into a BCC unit cell and for a BCC unit cell the number of atoms per unit cell will be 2 (Z = 2). The amount of sodium given is 4.6 g, so the number of atoms in sodium in 4.6g will be: N=nNAN=nNA n = mM = 4.623n = mM = 4.623 Putting the values, we get: N = 4.623 × 6.022 × 1023N = 4.623 × 6.022 × 1023 N = 1.2046 × 1023N = 1.2046 × 1023 Number of unit cell will be = NZNZ =1.2046 × 1023/2=6.023 × 1023 Number of unit cell will be = 6.023 × 1022
