Derive Bragg's equation.

In the following figure of beams, the phases of the beams coincide only when the incident angle equals the reflecting angle. The incident beams are parallel to each other until they reach point Z . When they are at point Z , they strike the surface and travel upwards. At point B the 2nd beam scatters. AB + BC is the distance travelled by the 2nd beam. The extra distance is termed as the integral multiple of the wavelength. nλ = AB + BC We know that AB + BC nλ = 2 AB ------------ (1) Further, D is the hypotenuse of the right ΔABZ . Also AB is the opposite side of θ angle. Hence, AB = d sinθ ------------(2) Substitution of (1) in (2) we get: nλ = 2 d sinθ The equation derived is called Bragg's equation.

Silver crystallizes in FCC lattice. If edge length of the cell is 4.07 × 10 - 8 c m and density is 10.5 g c m - 3 . Calculate the atomic mass of silver.

Given, Edge length of the cell ( a ) = 4.07 × 10 - 8 c m Density d = 10.5 g c m - 3 We also know that: the lattice is FCC type, the number of atoms per unit cell , Z = 4 N A = 6.022 × 10 23 m o le - 1 Using the relation d = Z M a 3 N A Therefore, M = da 3 N A Z = 10 .5 gcm - 3 x 4 .077 × 10 - 8 cm 3 × 6 .022 × 10 23 mole - 1 4 = 107.13 g mole - 1 Therefore, the atomic mass of silver = 107 .13 U

E M B I B E

Intermediate Second Year Chemistry>Chapter 1 - Solid State>Intext Questions>Q 1.3

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12th Andhra Pradesh Board

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

Important Questions on Solid State

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12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Chemistry>Chapter 1 - Solid State>Intext Questions>Q 1.4

Why is glass considered a super cooled liquid?

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12th Andhra Pradesh Board

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Intermediate Second Year Chemistry>Chapter 1 - Solid State>Intext Questions>Q 1.5

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 cleavage property?

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12th Andhra Pradesh Board

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Intermediate Second Year Chemistry>Chapter 1 - Solid State>Intext Questions>Q 1.6

Classify the following solids in different categories based on the nature of intermolecular forces operating in them:

Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

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Intermediate Second Year Chemistry>Chapter 1 - Solid State>Intext Questions>Q 1.7

Solid A Is a very hard electrical insulator in solid as well as In molten state and melts at extremely high temperature. What type of solid is it?

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