The Solid State

Question 77

What happens when CdCl2 is added to AgCl?

When AgCl is doped with CdCl2 a cation vacancy defect is created i.e. An Ag+ ion from the lattice is absent its position due to presence of adjacent Cd++ ion.
Question 78

Name the solid substance in which cations occupy all the tetrahedral voids.

 Na2O is the solid in which cation occupy all the tetrahedral voids. in Na2O, Na+ ion is surrounded by four oxide ion and oxide ion surrounded by the eight sodium ion.
Question 79

What is the effect of Frenkel defect on electrical conductivity of the solid?

Frenkel defect tends to increase the dielectric constant of the crystal. Compounds having such defect conduct electricity to a small extent. When electric field is applied, an ion moves from its lattice site to occupy a hole, it creates a new hole. In this way, a hole moves from one end to the other. Thus, it conducts electricity across the crystal. Due to the presence of holes, stability (or the lattice energy) of the crystal decreases.
Question 80

Mention one property which is caused due to the presence of F-centre in a solid.

If F-centres are introduced into a transparent crystal lattice then they will induce colour into the materiale for example NaCl heated in sodium vapours the crystal becomes coloured.

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