Advertisements
Advertisements
प्रश्न
The density of iridium is 22.4 g/cm3. The unit cell of iridium is fcc. Calculate the radius of iridium atom. Molar mass of iridium is 192.2 g/mol.
Advertisements
उत्तर
Given: Type of unit cell is fcc.
Density of iridium (ρ) = 22.4 g/cm3
Molar mass of iridium = 192.2 g/mol
To find: Radius of iridium atom (r)
Formula used:
1. Density (ρ) = `"M n"/("a"^3 "N"_"A")`
2. For fcc unit cell, r = 0.3535 a
Calculation: For fcc unit cell, n = 4, using formula (i)
Density (ρ) = `"M n"/("a"^3 "N"_"A")`
`22.4 "g cm"^-3 = (192.2 "g mol"^-1 xx 4 "atom")/("a"^3 xx 6.022 xx 10^23 "atom mol"^-1)`
`"a"^3 = (192.2 xx 4)/(22.4 xx 6.022 xx 10^23)`
a = `root(3)((192.2 xx 4)/(22.4 xx 6.022 xx 10^23))`
= `root(3)((192.2 xx 4 xx 10^-23)/(22.4 xx 6.022))`
`= root(3)((192.2 xx 40 xx 10^-24)/(22.4 xx 6.022))`
`= root(3)((192.2 xx 40 xx (10^-8)^3)/(22.4 xx 6.022))`
`= root(3)((192.2 xx 40)/(22.4 xx 6.022)) xx 10^-8`
= 3.849 × 10-8 cm
= 384.9 pm
Using formula (ii)
r = 0.3535 a
r = 0.3535 × 384.9 pm
= 135.7 pm ≈ 136 pm
Radius of iridium atom (r) is 136 pm.
संबंधित प्रश्न
Answer the following in one or two sentences.
Mention two properties that are common to both hcp and ccp lattices.
Answer the following in brief.
Cesium chloride crystallizes in a cubic unit cell with Cl– ions at the corners and a Cs+ ion in the center of the cube. How many CsCl molecules are there in the unit cell?
Aluminium crystallizes in a cubic close-packed structure with a unit cell edge length of 353.6 pm. What is the radius of Al atom? How many unit cells are there in 1.00 cm3 of Al?
In ionic crystalline solid atoms of element Y form hcp lattice. The atoms of element X occupy one-third of tetrahedral voids. What is the formula of the compound?
Calculate the packing efficiency for bcc lattice.
In case of hcp structure, how are spheres in first, second and third layers arranged?
A substance crystallizes in fcc structure. The unit cell edge length is 367.8 pm. Calculate the molar mass of the substance if its density is 21.5 g/cm3.
A compound of X and Y crystallizes in ccp structure in which the X atoms occupy the lattice points at the corners of cube and Y atoms occupy the centres of each of the cube faces. The formula of this compound is ____________.
The number of particles in 1 g of a metallic crystal is equal to ____________.
The vacant space in simple cubic lattice is ____________.
Which of the following contains the highest number of atoms?
The percentage of vacant space of bcc unit cell is ____________.
Which among the following crystal structures the edge length of unit cell is equal to twice the radius of one atom?
Which of the following is INCORRECT?
Atoms of elements A and B crystallize in hep lattice to form a molecule. Element A occupies 2/3 of tetrahedral voids, the formula of molecule is ______.
Copper crystallises with fee unit cell. If the radius of copper atom is 127.8 pm, calculate the density of copper? (At. mass: Cu = 63.55 g mol-1)
What is the percentage of void space in bcc type of in unit cell?
An element crystallizes in a bee lattice with cell edge of 500 pm. The density of the element is 7.5 g cm-3. How many atoms are present in 300 g of metal?
AB is an ionic solid. If the ratio of ionic radius of A+ and B- is 0.52, what is the coordination number of B- ?
The relation between the radius of the sphere and the edge length in the body-centred cubic lattice is given by the formula ______.
A compound made of elements C and D crystallizes in a fee structure. Atoms of C are present at the corners of the cube. Atoms of D are at the centres of the faces of the cube. What is the formula of the compound?
The packing efficiency of bcc is ______.
A compound has a hep structure. Calculate the number of voids in 0.4 mol of it.
Find the edge length of bcc unit cell if radius of metal atom is 126 pm.
