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Copper crystallises into a fcc lattice with edge length 3.61 x10 ^ -8 cm. Show that the calculated density is in agreement with its measured value of 8.92 g cm^ -3.

1.15    Copper crystallises into a fcc lattice with edge length 3.61\times 10^{-8}cm. Show that the calculated density is in agreement with its measured value of 8.92\; g\; cm^{-3}.

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The relation between density and edge lenght gives : 

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

Since it crystallises in fcc lattice, thus z = 4.

Molar mass of copper = 63.546 u.

So,          

                                                              Density = \frac{4\times63.546}{(3.61\times10^{-8})^3\times6.022\times10^{23}}\ cm

                                                                                 = 8.97\ g\ cm^{-3}

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