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The Third Law of Thermodynamics is specifically confined to pure crystalline solids because:
The NCERT text explicitly states, 'The statement is confined to pure crystalline solids because theoretical arguments and practical evidences have shown that entropy of solutions and super cooled liquids is not zero at 0 K.'
The primary importance of the Third Law of Thermodynamics lies in its ability to permit the calculation of:
The text highlights, 'The importance of the third law lies in the fact that it permits the calculation of absolute values of entropy of pure substance from thermal data alone.'
Which type of molecular motion is described by molecules spinning like a top?
The context explains, 'Mol ecules of a substance may move in a straight line in any direction, they may spin like a top and the bonds in the molecules may stretch and compress. These motions of the molecule are called translational, rotational and vibrational motion respectively.' Spinning like a top corresponds to rotational motion.
What happens to the entropy of a substance as its temperature rises?
The text states, 'When temperature of the system rises, these motions become more vigorous and entropy increases.'
Consider the following process: 'Temperature of a crystalline solid is raised from 0 K to 115 K.' What happens to the entropy?
According to Problem 5.10 (ii) and its solution, 'At 0 K, the constituent particles are static and entropy is minimum. If temperature is raised to 115 K, these begin to move and oscillate about their equilibrium positions in the lattice and system becomes more disordered, therefore entropy increases.'
Why is the entropy of solutions and supercooled liquids not zero at 0 K?
The text mentions, 'theoretical arguments and practical evidences have shown that entropy of solutions and super cooled liquids is not zero at 0 K.' This implies they lack the 'perfect order' characteristic of a pure crystalline solid at absolute zero, retaining some residual disorder (multiple microstates).
Which of the following is NOT a type of molecular motion mentioned in the context of entropy?
The text describes 'translational, rotational and vibrational motion' as contributing to entropy. Nuclear motion is not mentioned in this context.
As temperature is lowered, what happens to the entropy of a substance?
The text explicitly states, 'On the other hand when temperature is lowered, the entropy decreases.'
The increase in entropy in isolated systems is the natural direction of a spontaneous change. This statement is a part of which law of thermodynamics?
The text states, 'Therefore, increase in entropy in such systems is the natural direction of a spontaneous change. This, in fact is the second law of thermodynamics.'
What is the IUPAC name for o-Cresol?
According to the provided context, o-Cresol has the IUPAC name 2-Methylphenol. Ortho- (o-) indicates substituents at positions 1 and 2, and since phenol is the parent, the methyl group is at the 2-position.
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