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Chapter 12: Problem 68

Classify each of the following statements as true or false: (a) For molecular solids, the melting point generally increases as the strengths of the covalent bonds increase. (b) For molecular solids, the melting point generally increases as the strengths of the intermolecular forces increase.

Short Answer

Expert verified
Statement (a) is false as the melting point of molecular solids is not directly affected by the strength of covalent bonds within the molecules. Statement (b) is true as the melting point generally increases with the increase in the strengths of the intermolecular forces between the molecules.

Step by step solution

01

Statement (a): Melting point and covalent bond strength

Molecular solids are composed of individual molecules held together by covalent bonds within the molecules and intermolecular forces between the molecules. When we talk about the strength of covalent bonds, we are referring to the forces within the molecule itself. However, when a molecular solid melts, it does not involve the breaking of covalent bonds within the molecules. Instead, it involves the breaking of intermolecular forces between the molecules. So, the strength of covalent bonds within the molecule does not directly affect the melting point of a molecular solid. Hence, we can classify statement (a) as false.
02

Statement (b): Melting point and strength of intermolecular forces

As mentioned earlier, molecular solids are held together by intermolecular forces between the molecules. These forces can be dipole-dipole interactions, hydrogen bonding, or Van der Waals forces. The melting point of a molecular solid is directly related to the strength of these intermolecular forces. When a molecular solid melts, the intermolecular forces between the molecules are broken, allowing the molecules to move freely. If the intermolecular forces are stronger, more energy will be required to break them, resulting in a higher melting point. Therefore, the melting point generally increases as the strengths of the intermolecular forces increase. Thus, we can classify statement (b) as true.

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Most popular questions from this chapter

Which of the following statements does not follow from the fact that the alkali metals have relatively weak metal-metal bonding? (a) The alkali metals are less dense than other metals. (b) The alkali metals are soft enough to be cut with a knife. (c) The alkali metals are more reactive than other metals. (d) The alkali metals have higher melting points than other metals. (e) The alkali metals have low ionization energies.

The densities of the elements Cr, Mn, Fe, and Cu are 7.15 , \(7.30,7.87,\) and \(8.96 \mathrm{~g} / \mathrm{cm}^{3}\), respectively. One of these elements crystallizes in a face-centered cubic structure; the other three crystallize in a body-centered cubic structure. Which one crystallizes in the face- centered cubic structure? Justify your answer.

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Indicate whether the following statement is true or false: For an addition polymerization, there are no by-products of the reaction (assuming \(100 \%\) yield).
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