# 1.11   Silver crystallises in fcc lattice. If edge length of the cell is $4.07\times 10^{-8}cm$ and density is $10.5\; g\; cm^{-3}$ , calculate the atomic mass of silver.

The relation between density, molar mass and edge length is given by:-

$Density = \frac{z.M}{a^3.N_A}$

It is given that silver crystallises in fcc lattice, so the value of z = 4. (since it is known that 4 atoms are completely efficient in fcc lattice)

$M = \frac{Density.a^3.N_A}{z}$

$= \frac{10.5\ g\ cm^{-3} \times (4.07\times10^{-8}cm)^3\times N_A}{4}$

Convert these into SI units,                $= 107.09\ u$

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