pressure (atm) 0- 0.6- The temperature on a sample of pure X held at 0.53 atm and 136. °C is decreased until the sample condenses. The temperature is then held constant and the pressure is increased by 0.25 atm. On the phase diagram below draw a pati that shows this set of changes. 1.2 0 200 400 temperature (K) G لكا 00. 18 Ar

8.87 Use the vapor pressure curves illustrated here to answer the questions that follow. (a) What is the vapor pressure of ethanol (C2H5OH) at 60°C? (b) Considering only carbon disulfide (CS2) and ethanol, which has the stranger intermolecular forces in the liquid state? (c) At what temperature does heptane (C7H16) have a vapor pressure of 500 mm Hg? (d) What are the approximate normal boiling pains of each of the three substances? (e) At a pressure of 400 mm Hg and a temperature of 70°C, is each substance a liquid, a gas, or a mixture of liquid and gas?

A fluorocarbon, CF4, has a critical temperature of 45.7 C and a critical pressure of 37 atm. Are there any conditions under which this compound can be a liquid at room temperature? Explain briefly.

The phase diagram for water over a relative narrow pressure and temperature range is given in Figure 9.19. A phase diagram over a considerably wider range of temperature and pressure (kbar) is given nearby. This phase diagram illustrates the polymorphism of ice, the existence of a solid in more than one form. In this case, Roman numerals are used to designate each polymorphic form. For example, Ice I, ordinary ice, is the form that exists under ordinary pressures. The other forms exist only at higher pressures, in some cases extremely high pressure such as Ice VII and Ice VIII. Using the phase diagram, give the approximate P and T conditions at the triple point for Ice III, Ice V, and liquid water. Determine the approximate temperature and pressure for the triple point for Ices VI, VII, and VIII. What is anomalously different about the fusion curves for Ice VI and Ice VII compared to that of Ice I? What phases exist at 8 kbar and 20 °C? At a constant temperature of −10 °C, start at 3 kbar and increase the pressure to 7 kbar. Identify all the phase changes that occur sequentially as these conditions change. Explain why there is no triple point for the combination of Ice VII, Ice VIII, and liquid water.

Consider the following data for the vapor pressure of diethyl ether, a widely used anesthetic in the early days of surgery. Follow the instructions in Question 13 to estimate the heat of vaporization of diethyl ether.