Ideal and Real Gases
Ideal gases obey conditions of the general gas laws under all states of pressure and temperature. Ideal gases are also named perfect gases. The attributes of ideal gases are as follows,
Gas Laws
Gas laws describe the ways in which volume, temperature, pressure, and other conditions correlate when matter is in a gaseous state. The very first observations about the physical properties of gases was made by Robert Boyle in 1662. Later discoveries were made by Charles, Gay-Lussac, Avogadro, and others. Eventually, these observations were combined to produce the ideal gas law.
Gaseous State
It is well known that matter exists in different forms in our surroundings. There are five known states of matter, such as solids, gases, liquids, plasma and Bose-Einstein condensate. The last two are known newly in the recent days. Thus, the detailed forms of matter studied are solids, gases and liquids. The best example of a substance that is present in different states is water. It is solid ice, gaseous vapor or steam and liquid water depending on the temperature and pressure conditions. This is due to the difference in the intermolecular forces and distances. The occurrence of three different phases is due to the difference in the two major forces, the force which tends to tightly hold molecules i.e., forces of attraction and the disruptive forces obtained from the thermal energy of molecules.
Explain the Jahn-Teller effect and provide an example. (
John- Teller effect :- The Jahn-Teller (J-T) theorem states that in molecules/ ions that have a degenerate ground-state, the molecule/ion will distort to remove the degeneracy. This is a fancy way of saying that when orbitals in the same level are occupied by different numbers of electrons, this will lead to distortion of the molecule. For us, what is important is that if the two orbitals of the eg level have different numbers of electrons, this will lead to J-T distortion.d8 Configuration (t2g6) eg2, keeping in mind that eg orbitals are doubly degenerate, every orbital will contain 1 electron each.. i.e. symmetrically filled.
while in the case of d9 system eg orbitals are unsymmetrically filled, t2g6 ,eg3 , now eg orbitals are unsymmetrically filled 2 & 1 electrons in individual orbitals, Jahn-Teller theorem is applicable , which is reflected in having unequal bond lengths, in Octahedral case either two bonds longer four bonds shorter, the symmetry is lowered from Octahedral point group to D4h point group . (e.g. Cu 2+).
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