First slide
Density of unit cell
Question

Lithium has a  b c c structure. Its density is 530 kg m-3  and its atomic mass is 6.94 g mol-1 . Calculate the edge length of a unit cell of lithium metal. NA=6.02×1023 mol-1

Moderate
Solution

 For bcc,Z=2,ρ=530 kg m-3,at.mass of Li=6.94 g mol-1, 

NA=6.02×1023 mol-1

ρ=530 kg m-3=530×1000 g1×(100)3 cm3=0.53 g cm-3

ρ=Z× At. mass NA×a3

a3=Z× At. mass NA×ρ=2×6.946.02×1023×0.53=43.5×10-24 cm3a=352×10-10 cm=352pm

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