# Homework Solution: Chromium forms a hexagonal close packed crystal structure. Determin… Chromium forms a hexagonal close packed crystal structure. Determine the theoretical density of chromium rho = nA/V_cN_a n = number of atoms per unit cell (atoms): V_c = volume of the unit cell (units^3) N_A= avogadro's number (atoms/mol): A = atomic weight of the atom = 51.996 g/mol Chromium forms a hexagonal rest packed crystal composition. Determine the speculative hebetude of chromium rho = nA/V_cN_a n = compute of specks per individual cell (atoms): V_c = bulk of the individual cell (units^3) N_A= avogadro’s compute (atoms/mol): A = ultimate consequence of the speck = 51.996 g/mol

## Expert Acceptance

For the HCP packing composition, we keep n = 6

Bulk of individual cell, Vc = 33.94*r3

Here, r = radius of Cr speck = 200 pm = 2*10-10 m

So,

Vc = 33.94*(2*10-10)3 = 271.52*10-30 m3.

Na = 6.02*1023 atoms/mol

Putting these values we get:

Density, d = (6*51.996)/(271.52*10-30*6.02*1023) = 1.908*106 g/m3