Chemistry Test - 28

The number of tetrahedral voids form is equal to twice the number of atoms of element X. Number of atoms of Y is 3/4th the number of tetrahedral voids i.e. 3/2 times the number of atoms of X. Therefore, the ratio of numbers of atoms of X and Y are 2:3, hence X₂Y₃.

The interactions between the components of a non-ideal solution showing negative deviation are greater than the pure components. The change in volume and enthalpy after mixing is negative, i.e., ΔV_mixing = -ve, ΔH_mixing = -ve.

Since particles are assumed to be spheres and volume of one sphere is 4/3 πr³, total volume of all particles in 

H₂O + C₂H₅OH forms an azeotrope with a boiling point of 351.15 K. CHCl₃ + C₂H₅ OH forms an azeotrope with a boiling point of 332.3 K. HCl + H₂O forms an azeotrope with a boiling point of 383 K. Benzene + Toluene is an ideal solution and hence does not form an azeotrope.

Atomic mass of Al = 27g/mole (contains 6.022 x 10²³ Al atoms)

Since it exhibits FCC, there are 4 Al atoms/unit cell.

If 27g Al contains 6.022 x 10²³ Al atoms then 54g Al contains 1.2044 x 10²⁴atoms.

Thus, if 1 unit cell contains 4 Al atoms then number of unit cells containing 1.2044 x 10²⁴ atoms=(1.2044 x 10²⁴ x 1)/4 = 3.011 × 10²³ unit cells.

Azeotropes have the same concentration in the vapour phase and the liquid phase. In case of minimum boiling azeotropes, the boiling point of the azeotrope is lesser than the boiling point of either of the pure components. In case of maximum boiling azeotropes, the boiling point of the azeotrope is higher than the boiling point of either of the pure components.

For body-centered unit cells, the relation between radius of a particle ‘r’ and edge length of unit cell ‘a’ is given as  pm is the radius of the metal atom.

The Gibbs free energy of a system at any moment in time is defined as the enthalpy of the system minus the product of the temperature times the entropy of the system. For ideal solutions, the value of the Gibbs Free energy is always negative as mixing of ideal solutions is a spontaneous process.

A unit cell is characterized by six parameters i.e. the three common edge lengths a, b, c and three angles between the edges that are α, β, γ. These are referred to as inter-axial lengths and angles, respectively. The position of a unit cell can be determined by fractional coordinates along the cell edges.

Each point of the particle’s position is referred to as ‘lattice point’ or ‘lattice site’. Every lattice point represents one constituent particle which may be an atom, ion or molecule.