An element with density 2.8 g cm−3 forms of the f.c.c. unit cell with edge length 4 X10 −8 cm. Calculate the molar mass of the element. (Given: NA = 6.022 X 10 23 mol −1 ) - Wired Faculty

The Solid State

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An element with density 2.8 g cm−3 forms of the f.c.c. unit cell with edge length 4 X10⁻⁸ cm. Calculate the molar mass of the element.
(Given: NA = 6.022 X 10²³ mol ⁻¹)

Solution

Edge length, a = 4 x 10-8 cm

Density, d = 2.8 g cm-3

As the lattice is fcc type, the number of atoms per unit cell, z is 4.

Avogadro's number, NA = 6.022 x 1023 mol-1

Molar mass can be calculated with the help of given relation:
$straight d space equals space fraction numerator straight Z space straight x space straight M over denominator straight N subscript straight A space straight x space straight a cubed end fraction straight m equals space fraction numerator straight N subscript straight A space space straight x space straight a cubed space straight x space straight d over denominator straight Z end fraction fraction numerator 2.8 space straight x space left parenthesis 4 space straight x space 10 to the power of negative 8 end exponent right parenthesis cubed space straight x space 6.022 space straight x space 10 to the power of 23 over denominator 4 end fraction space equals space 26.98 space straight g space mol to the power of negative 1 end exponent approximately equal to space 27 space straight g space mol to the power of negative 1 end exponent$

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The Solid State

An element with density 2.8 g cm−3 forms of the f.c.c. unit cell with edge length 4 X10⁻⁸ cm. Calculate the molar mass of the element.
(Given: NA = 6.022 X 10²³ mol ⁻¹)

Some More Questions From The Solid State Chapter

Why are solids rigid?

Why do solids have a definite volume?

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

Why is glass considred a super-cooled liquid?

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?

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
sulphate, graphite, rubidium, argon, silicon carbide.

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What type of solids are electrical conductors, malleable and ductile?

Give the significance of a 'lattice point'.

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For Daily Free Study Material Join wiredfaculty

The Solid State

An element with density 2.8 g cm−3 forms of the f.c.c. unit cell with edge length 4 X10−8 cm. Calculate the molar mass of the element.(Given: NA = 6.022 X 1023 mol −1)

Some More Questions From The Solid State Chapter

Why are solids rigid?

Why do solids have a definite volume?

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

Why is glass considred a super-cooled liquid?

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?

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 sulphate, graphite, rubidium, argon, silicon carbide.

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?

Ionic solids conduct electricity in liquid state but not in solid state. Explain.

What type of solids are electrical conductors, malleable and ductile?

Give the significance of a 'lattice point'.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

An element with density 2.8 g cm−3 forms of the f.c.c. unit cell with edge length 4 X10⁻⁸ cm. Calculate the molar mass of the element.
(Given: NA = 6.022 X 10²³ mol ⁻¹)

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
sulphate, graphite, rubidium, argon, silicon carbide.