(a) Some of the glass objects recovered from ancient monuments look milky instead of being transparent. Why?
(b) Iron (II) oxide has a cubic structure and each side of the unit cell is 5. If density of the oxide is 4 g cm-3, calculate the number of Fe2+ and O2- ions present in each unit cell.
[Atomic mass : Fe = 56 u, O = 16 u; Avogadro's number = 6.0231023 mol-1]
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Concept Questions :-
(a) Some of the glass objects found from ancient monuments look to be milky in appearance because of crystallisation of glass.
(b) Volume of unit cell = a3 = (5) = (510-8)3
= 1.2510-22 cm
Density of FeO = 4g cm-3
Mass of unit cell = Volume Density
= 1.2510-224 g
= 510-22 g
Mass of FeO molecule per unit cell
= = 4.19 4
Thus 4Fe+2, 4O-2 will be present in each unit cell.