Chapter Chosen

The Solid State

Book Chosen

Chemistry I

Subject Chosen


Book Store

Download books and chapters from book store.
Currently only available for.
CBSE Gujarat Board Haryana Board

Previous Year Papers

Download the PDF Question Papers Free for off line practice and view the Solutions online.
Currently only available for.
Class 10 Class 12
In the cubic crystal of CsCl (d = 3.97 g cm–3), the eight corners are occupied by CIwith a Cs+ at the centre and vice versa. Calculate the distance between the neighbouring Cs+ and CI ions. What is the radius ratio of the two ions ? (At. mass of Cs = 132.91 and CI = 35.45).

In a unit cell there are one Cs and 1 x 8/8 =1 chlorine  (Cl-) such that one CsCl molecule 

As we have given 
density = 3.97 g cm-3
Mass of CsCl = 168.36g
Number of unit cell(Z) = 1

apply formula d= Z xMa3 x NA3.97 = 1 x 168.36a3 x 6.023 x 1023a = 4.13 x 10-8 cma =4.13 A0

for a cube of side  length 4.13A0 diagonal

                                    =3a i.e.,3 x 4.13 = 7.15A0

as it is a BCC with  Cs+ at centre radius r+ and Cl- at corner radius r- so, 

2r+ +2r- =7.15 or r+ +r- =3.57A0

such that distance between neighbouring Cs+ and Cl- =3.57A0

now assume two Cl- ion touch with each other so length of unit cell = 2r- =4.13
r- =2.06A0
r+ =3.57 -2.06 =1.51

r+/r-=1.51/2.06 =0.73


Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show clevage property?

Refractive index of a solid which have the same value along all directions are isotropic in nature. It would not show cleavage property.

Why are solids rigid?

Solids are rigid because the internuclear distance between the  molecules of a solid are very less and closely packed and their positions are fixed due to the strong forces of attraction between them.

Why is glass considred a super-cooled liquid?

Glass is amorphous solids and  have a tendency to flow, though very slowly. Therefore, these are called pseudo solids or super cooled liquids .

Why do solids have a definite volume?

A solid have a definite volume because the inter molecular distance  between its molecules are fixed.

Classify the following as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Amorphous solids: Polyurethane, teflon, cellophane, polyvinyal chloride, fibre glass.
Crystalline solids: naphthlene, benzoic acid, potassium nitrate, copper.