Q13 of 26 Page 1

An element with molar mass 27g mol-1 forms a cubic unit cell with an edge length of 4.05 x 10-8cm. If its density is 2.7g cm-3, what is the nature of cubic unit cell?

Given:


Molar mass (M) = 27g mol-1 =0.027 Kg/mol


edge length (a) = 4.05 x 10-8cm = 4.05 x 10-10 m


density (d) = 2.7g cm-3 =2.7 Kg/m3



Z = atoms per unit cell (tells us nature of unit cell)


NA= Avagadro’s number



As there are 4 atoms per unit cell, it could have either face centred cubic (fcc) or cubic close packing(ccp) type of arrangement, as both have 4 atoms per unit cell.


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