Question

The pyknometric density of sodium chloride crystal is 2.165×103kgm–3 while its X-ray density is 2.178×103kgm–3. The fraction of unoccupied sites in sodium chloride crystal is :

Answer 1

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Molar volume from pycnometric density =M2.165×103m3

Molar volume from X-ray density =M2.178×103m3

∴ Volume occupied =M103(12.165−12.178)m3

⇒M103(0.0132.165×2.178)m3

Fraction unoccupied =(0.013M×10−32.165×2.178)M×10−32.165

⇒5.96×10−3