Problem 61
Which of the following are molecular solids and which are covalent solids: \(\mathrm{Se}_{8}, \mathrm{HBr}, \mathrm{Si}, \mathrm{CO}_{2}, \mathrm{C}, \mathrm{P}_{4} \mathrm{O}_{6}\) \(\mathrm{SiH}_{4} ?\)
Problem 63
Explain why diamond is harder than graphite. Why is graphite an electrical conductor but diamond is not?
Problem 64
What is an amorphous solid? How does it differ from a crystalline solid?
Problem 65
Define glass. What is the chief component of glass? Name three types of glass.
Problem 66
What is a phase change? Name all possible changes that can occur among the vapor, liquid, and solid phases of a substance.
Problem 67
What is the equilibrium vapor pressure of a liquid? How is it measured, and how does it change with temperature?
Problem 68
Use any one of the phase changes to explain what is meant by dynamic equilibrium.
Problem 69
Define the following terms: (a) molar heat of vaporization, (b) molar heat of fusion, (c) molar heat of sublimation. What are their typical units?
Problem 71
What can we learn about the intermolecular forces in a liquid from the molar heat of vaporization?
Problem 74
As a liquid is heated at constant pressure, its temperature rises. This trend continues until the boiling point of the liquid is reached. No further rise in temperature of the liquid can be induced by heating. Explain.
