New Concepts/Shortcuts 24

Question 1

whats point and crystal defects?!

Answer 1

Point defects are the irregularities or deviations from ideal arrangement around a point or an atom in a crystalline substance, whereas the line defects are the irregularities or deviations from ideal arrangement in entire rows of lattice points. These irregularities are called crystal defects.

Question 2

what are stoichiometric defects?

and its types?

Answer 2

These are the point defects that do not disturb the stoichiometry of the solid. They are also called intrinsic or thermodynamic defects.

Basically these are of two types, vacancy defects and interstitial defects.

Question 3

whats vacancy defects?

Answer 3

When some of the lattice sites are vacant, the crystal is said to have vacancy defect. This results in decrease in density of the substance. This defect can also develop when a substance is heated.

Question 4

whats interstitial defect?

Answer 4

When some constituent particles (atoms or molecules) occupy an interstitial site, the crystal is said to have an interstitial defect . This defect increases the density of the substance.

Question 5

Whats Frenkel Defect?!

Answer 5

This defect is shown by ionic solids. The smaller ion (usually cation) is dislocated from its normal site to an interstitial site. It creates a vacancy defect at its original site and an interstitial defect at its new location. Frenkel defect is also called dislocation defect.

It does not change the density of the solid

Question 6

which kind of defects are shown in non ionic solids?

Answer 6

Vacancy and interstitial defects are shown by non-ionic solids

Question 7

which defects are found in ionic solids?

Answer 7

they show these defects as Frenkel and Schottky defects.

Question 8

frenkel defect is shown by ionic substance which has__________

Answer 8

Frenkel defect is shown by an ionic substance in which there is a large difference in the size of ions, for example, ZnS, AgCl, AgBr, and AgI due to the small size of Zn2+ and Ag+ ions.

Question 9

whats schottky defect?

Answer 9

It is basically a vacancy defect in ionic solids. In order to maintain electrical neutrality, the number of missing cations and anions is equal. Like a simple vacancy defect, the Schottky defect also decreases the density of the substance.

For example, NaCl, KCl, CsCl, and AgBr. It may be noted that AgBr shows both, Frenkel as well as Schottky defects.

Question 10

which defect is famous in ionic solids?

Answer 10

Schottky defect

Question 11

which solid shows both kinda defect? schottky and frenkel?!

Answer 11

AgBr

Question 12

whats impurity defects?

Answer 12

If molten NaCl containing a little amount of SrCl2 is crystallized, some of the sites of Na+ ions are occupied by Sr2+. Each Sr2+ replaces two Na+ ions. It occupies the site of one ion and the other site remains vacant. The cationic vacancies thus produced are equal in number to that of Sr2+ ions.
Another similar example is the solid solution of CdCl2 and AgCl

Question 13

whose law is the raoults a special case of?

Answer 13

Raoult’s law becomes a special case of Henry’s law

Question 14

whose law is the raoults a special case of?

Answer 14

Raoult’s law becomes a special case of Henry’s law

Question 15

eg of perfectly ideal solutions

Answer 15

n-hexane and n-heptane, bromoethane and chloroethane, benzene and toluene, etc. fall into this category.

Question 16

the concept of a chance in boiling point due to positive deviation

Answer 16

A-B interactions are weaker than those between A-A or B-B, i.e., in this case, the intermolecular attractive forces between the solute-solvent molecules are weaker than those between the solute-solute and solvent-solvent molecules. This means that in such solutions, molecules of A (or B) will find it easier to escape than in a pure state. This will increase the vapor pressure and result in a positive deviation.

Question 17

eg of mixtures showing positive deviation and why?

Answer 17

Mixtures of ethanol and acetone behave in this manner.

In pure ethanol, molecules are hydrogen bonded. On adding acetone, its molecules get in between the host molecules and break some of the hydrogen bonds between them. Due to weakening of interactions, the solution shows positive deviation from Raoult’s law

Question 18

what are colligative properties?

Answer 18

All these properties depend on the number of solute particles irrespective of their nature relative to the total number of particles present in the solution. Such properties are called colligative properties