Problem 87
How is the rate of evaporation of a liquid affected by (a) temperature, (b) the surface area of a liquid exposed to air, (c) intermolecular forces?
Problem 88
The following compounds, listed with their boiling points, are liquid at \(-10^{\circ} \mathrm{C}:\) butane, \(-0.5^{\circ} \mathrm{C} ;\) ethanol, \(78.3^{\circ} \mathrm{C} ;\) toluene, \(110.6^{\circ} \mathrm{C}\). At \(-10^{\circ} \mathrm{C}\), which of these liquids would you expect to have the highest vapor pressure? Which the lowest? Explain.
Problem 89
Freeze-dried coffee is prepared by freezing brewed coffee and then removing the ice component with a vacuum pump. Describe the phase changes taking place during these processes.
Problem 91
Explain why steam at \(100^{\circ} \mathrm{C}\) causes more serious burns than water at \(100^{\circ} \mathrm{C}\)
Problem 92
What is a phase diagram? What useful information can be obtained from studying a phase diagram?
Problem 93
Explain how water's phase diagram differs from those of most substances. What property of water causes the difference?
Problem 94
The blades of ice skates are quite thin, so the pressure exerted on ice by a skater can be substantial. Explain how this facilitates skating on ice.
Problem 95
A length of wire is placed on top of a block of ice. The ends of the wire extend over the edges of the ice, and a heavy weight is attached to each end. It is found that the ice under the wire gradually melts, so the wire slowly moves through the ice block. At the same time, the water above the wire refreezes. Explain the phase changes that accompany this phenomenon.
Problem 96
The boiling point and freezing point of sulfur dioxide are \(-10^{\circ} \mathrm{C}\) and \(-72.7^{\circ} \mathrm{C}\) (at \(\left.1 \mathrm{~atm}\right)\), respectively. The triple point is \(-75.5^{\circ} \mathrm{C}\) and \(1.65 \times 10^{-3} \mathrm{~atm},\) and its critical point is at \(157^{\circ} \mathrm{C}\) and 78 atm. On the basis of this information, draw a rough sketch of the phase diagram of \(\mathrm{SO}_{2}\).
Problem 98
Name the kinds of attractive forces that must be overcome to (a) boil liquid ammonia, (b) melt solid phosphorus \(\left(\mathrm{P}_{4}\right),(\mathrm{c})\) dissolve CsI in liquid \(\mathrm{HF},\) (d) melt potassium metal.
