Iron (II) oxide has a cubic structure and each of the unit cell is 5.0 A°. If density of the oxide is 4.0 g cm^-3, calculate the number of Fe²⁺and O^2– ions present in each unit cell.

Solution

Volume of the unit cell = (5 A°)
= (5 x 10^–8 cm)³= 125 x 10^–24 cm³= 1.25 x 10^–22 cm³Density of FeO = 4.0 g cm^–3
Therefore, mass of the unit cell
= 1.25 x 10^–22 cm³ x 4 g cm^–3= 5 x 10^–22g
Mass of all molecules of FeO
$= \frac{72}{6.022 \times 10^{23}} = 1.195 \times 10^{- 22} g$

Number of FeO molecules/unit cell
$= \frac{5 \times 10^{- 22} g}{1.195 \times 10^{- 22} g} = 4.19 \approx 4$

Thus, there are 4 Fe²⁺ ions and 4O^2– ions in each unit cell.

Some More Questions From The Solid State Chapter

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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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Distinguish between Hexagonal and monoclinic unit cells.

Distinguish between Face-centred and end-centred unit cells.

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The Solid State

Iron (II) oxide has a cubic structure and each of the unit cell is 5.0 A°. If density of the oxide is 4.0 g cm^-3, calculate the number of Fe²⁺and O^2– ions present in each unit cell.

Some More Questions From The Solid State Chapter

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'.

Name the parameters that characterize a unit cell.

Distinguish between Hexagonal and monoclinic unit cells.

Distinguish between Face-centred and end-centred unit cells.

What is the two-dimensional coordination number of a molecule in square close packed layer ?

A compound is formed by two elements M and N. The element N forms ccp and atoms of M occupy 1/3 of tetrahedral voids. What is the formula of the compound?

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The Solid State

Iron (II) oxide has a cubic structure and each of the unit cell is 5.0 A°. If density of the oxide is 4.0 g cm-3, calculate the number of Fe2+ and O2– ions present in each unit cell.

Some More Questions From The Solid State Chapter

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'.

Name the parameters that characterize a unit cell.

Distinguish between Hexagonal and monoclinic unit cells.

Distinguish between Face-centred and end-centred unit cells.

What is the two-dimensional coordination number of a molecule in square close packed layer ?

A compound is formed by two elements M and N. The element N forms ccp and atoms of M occupy 1/3 of tetrahedral voids. What is the formula of the compound?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Iron (II) oxide has a cubic structure and each of the unit cell is 5.0 A°. If density of the oxide is 4.0 g cm^-3, calculate the number of Fe²⁺and O^2– ions present in each unit cell.