Problem 99
Which of the following properties indicates very strong intermolecular forces in a liquid: (a) very low surface tension, (b) very low critical temperature, (c) very low boiling point, (d) very low vapor pressure?
Problem 100
At \(-35^{\circ} \mathrm{C}\), liquid HI has a higher vapor pressure than liquid HF. Explain.
Problem 103
Which of the following substances has the highest polarizability: \(\mathrm{CH}_{4}, \mathrm{H}_{2}, \mathrm{CCl}_{4}, \mathrm{SF}_{6}, \mathrm{H}_{2} \mathrm{~S} ?\)
Problem 104
\(\mathrm{X}\) rays of wavelength \(0.154 \mathrm{nm}\) are diffracted from a crystal at an angle of \(14.17^{\circ} .\) Assuming that \(n=1\), calculate the distance (in pm) between layers in the crystal.
Problem 105
At what angle will \(\mathrm{X}\) rays of wavelength \(0.154 \mathrm{nm}\) be diffracted from a crystal if the distance (in \(\mathrm{pm}\) ) between layers in the crystal is \(188 \mathrm{pm}\) ? (Assume \(n=1\).)
Problem 106
A \(\mathrm{CO}_{2}\) fire extinguisher is located on the outside of a building in Massachusetts. During the winter months, one can hear a sloshing sound when the extinguisher is gently shaken. In the summertime there is often no sound when it is shaken. Explain. Assume that the extinguisher has no leaks and that it has not been used.
Problem 107
What is the vapor pressure of mercury at its normal boiling point \(\left(357^{\circ} \mathrm{C}\right)\) ?
Problem 108
A flask of water is connected to a powerful vacuum pump. When the pump is turned on, the water begins to boil. After a few minutes, the same water begins to freeze. Eventually, the ice disappears. Explain what happens at each step.
Problem 112
A student is given four solid samples labeled W, X, Y, and \(Z\). All have a metallic luster. She is told that the solids could be gold, lead sulfide, mica (which is quartz, or \(\mathrm{SiO}_{2}\) ), and iodine. The results of her investigations are: (a) \(\mathrm{W}\) is a good electrical conductor; \(\mathrm{X}, \mathrm{Y},\) and \(\mathrm{Z}\) are poor electrical conductors. (b) When the solids are hit with a hammer, W flattens out, X shatters into many pieces, \(\mathrm{Y}\) is smashed into a powder, and \(\mathrm{Z}\) is not affected. (c) When the solids are heated with a Bunsen burner, Y melts with some sublimation, but \(\mathrm{X}, \mathrm{W}\), and \(Z\) do not melt. (d) In treatment with \(6 \mathrm{M} \mathrm{HNO}_{3}\), \(\mathrm{X}\) dissolves; there is no effect on \(\mathrm{W}, \mathrm{Y},\) or \(\mathrm{Z}\). On the basis of these test results, identify the solids.
Problem 113
Which of the following statements are false? (a) Dipoledipole interactions between molecules are greatest if the molecules possess only temporary dipole moments. (b) All compounds containing hydrogen atoms can participate in hydrogen-bond formation. (c) Dispersion forces exist between all atoms, molecules, and ions.
