NEET Chemistry The Solid State Questions Solved

Silver crystallizes in a face centred cubic system, 0.408 nm along each edge. The density of silver is 10.6 g/cm3 and the atomic mass is 107.9 g/mol. Calculate Avogadro's number.

(1) 6.00×1023 atom/mol

(2) 9.31×1023 atom/mol

(3) 6.23×1023 atom/mol

(4) 9.61×1023atom/mol

(1) The unit cell has a volume of (0.408 ×109m)3=6.79×1029m3 per unit cell and contains four atoms. The volume of 1 mole of silver is,

107.9g/mol(1×102m)310.6g=1.02×105m3/mol; where 107.9 g/mol is the molecular mass of the silver

The number of unit cells per mol. is,

1.02×105m3/mol1unit cell6.79×1029m3=1.50×1023 unit cells per mol.

and the number of atoms per mol. is, 4atomsunit cell1.50×1023unit cellmol=6.00×1023 atom/mol.  

Difficulty Level:

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