Q16 of 22 Page 1

Examine the given defective crystal:

X+ Y- X+ Y- X+


Y- O Y- X+ Y-


X+ Y- X+ O X+


Y- X+ Y- X+ Y-


Answer the following questions:


(i) Is the above defect stoichiometric or non-stoichiometric?


(ii) Write the term used for this type of defect. Give an example of the compound which shows this type of defect.


(iii) How does this defect affect the density of the crystal?


(i) The above defect is stoichiometric because the no. of missing cation and anion is equal. (a cation is missing from 2nd row and an anion is missing from 3rd row)


(ii) This defect is called Schottky defect. It is a vacancy defect shown by anionic substances in which cation and anion are of similar size.


An example of the compound which shows this type of defect is NaCl.


(iii) Since, the cations and anions are missing from the lattice thereby creating vacancy. Thus, density of crystal decreases.


More from this chapter

All 22 →
13

(i) Which one of the following is a polysaccharide : starch, maltose, fructose, glucose

(ii) Write one difference between -helix and -pleated sheet structures of protein.


(iii) Write the name of the disease caused by the deficiency of vitamin B12.


 14

(i) What type of isomerism is shown by the complex [Cr(H2O)6]Cl3 ?

(ii) On the basis of crystal field theory, write the electronic configuration for d4 ion if o > P.


(iii) Write the hybridization and shape of [CoF6]3-. (Atomic number of Co = 27)


 17

Conductivity of 2.5 10-4M methanoic acid is 5.25 10-5 Scm-1. Calculate its molar conductivity and degree of dissociation. Given: (H+) = 349.5 Scm2mol-1 and ⋀°(HCOO-) =50.5 Scm2mol-1.

 18

Write any three differences between Physisorption and Chemisorption.