The pyknometric density of sodium chloride crystal is 2.165 10^3 ~kg ~m ⁻³ while its X-ray density is 2.178 10^3 ~kg m ⁻³ . The fraction of unoccupied sites in sodium chloride crystal is:

Step-by-step solution

Molar volume from pyknometric density = M 2.165 10^3 ~m ^3 Molar volume of X-ray density = M 2.178 10^3 ~m ^3 Volume unoccupied = M 10^3 ( 1 2.165 - 1 2.178 ) m ^3 Fraction occupied aligned & = 0.013 10⁻³ 2.165 2.178 2.165 M 10⁻³ & =5.96 10⁻³ aligned Related Theory Pyknometric density is the closest approximation to true density calculated from the molecular weight and crystalline lattice of a substance.