Advertisements
Advertisements
प्रश्न
Aluminium crystallises in a cubic close-packed structure. Its metallic radius is 125 pm.
- What is the length of the side of the unit cell?
- How many unit cells are there in 1.00 cm3 of aluminium?
Advertisements
उत्तर
i. For cubic close-packed structure:
`r = a/(2 sqrt 2)`
`a = 2 sqrt 2 r`
= `2 sqrt 2 xx 125`
= `2 xx 1.414 xx 125`
= 353.55 pm
= 353.55 × 10−10 cm
= 3.54 × 10−8 cm
ii. Volume of one unit cell = a3
= (3.54 × 10−10)3 cm3
= (44.3 × 10−24) cm3
= 4.43 × 10−23 cm3
Hence, number of unit cells in 1.00 cm3
= `1.00/(4.43 xx 10^-23)`
= `1.00/4.43 xx 10^23`
= 0.225 × 1023
= 2.25 × 1022
संबंधित प्रश्न
A compound forms hexagonal close-packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?
The arrangement ABC ABC.... is referred to as ____________.
What is the coordination number in a square close packed structure in two dimensions?
In NaCl structure ____________.
Which of the following statement is not true about the hexagonal close packing?
Match the type of packing given in Column I with the items given in Column II.
| Column I | Column II |
| (i) Square close packing in two dimensions |
(a) Triangular voids |
| (ii) Hexagonal close packing in two dimensions |
(b) Pattern of spheres is repeated in every fourth layer |
| (iii) Hexagonal close packing in three dimensions |
(c) Coordination number 4 |
| (iv) Cubic close packing in three dimensions |
(d) Pattern of sphere is repeated in alternate layers |
How can you best describe the elongated octahedral structure of blue vitriol, CuSO4.5H2O?
The octane number of Iso-octane is
The crystal system of a compound with unit cell dimensions a = 0.387, b = 0.387 and c = 0.504 nm and α = β = 90° and ϒ = 120° is
A compound forms hexagonal close-packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?
Co-ordination number of sodium ion Na+ in Nacl is:-
The right options for the number of tetrahedral and octahedral voids in the hexagonal primitive unit cells is ______.
Element 'B' forms ccp structures and A occupies half of the octahedral voids, while oxygen atoms occupy all the tetrahedral voids. The structure of bimetallic oxide is ______.
Ionic radii of cation A+ and anion B- are 102 and 181 pm respectively. These ions are allowed to crystallize into an ionic solid. This crystal has cubic close packing for B-. A+ is present in all octahedral voids. The edge length of the unit cell of the crystal AB is ______ pm. (Nearest integer)
The density of a pure substance 'X' whose atoms pack in cubic close pack arrangement is 1 g/cc. If all tetrahedral voids are occupied by 'Y' atoms. The value of '3a' is ______ g/cc, if the density of resulting solid is 'a' g/cc.
[Given: Atomic mass (X) = 30 g/mol, (Y) = 20 g/mol]
What fraction of one edge centred octahedral void lies in one unit cell of FCC?
