Substance X is known to exist at 1 atm in the solid, liquid, or vapor phase, depending on the temperature. Additionally, the values of these other properties of X have been determined: melting point 25. °C boiling point 55. °C enthalpy of fusion 9.00 kJ/mol enthalpy of 49.00 kJ/mol vaporization 2.00 g/cm (solid) density 37. J.Kmol 1 1 (solid) olo 1.70 g/mL (liquid) heat capacity 51. J·Kmol (liquid) -1 Ar 43. J-к "mol (vapor) You may also assume X behaves as an ideal gas in the vapor phase. Suppose a small sample of X at 0 °C is put into an evacuated flask and heated at a constant rate until 15.0 kJ/mol of heat has been added to the sample. Graph the temperature of the sample that would be observed during this experiment. 100 90- ? 80- 70 60 50 40 30 20 10 10 15 heat added (kJ/mol) temperature (*C)

Substance X is known to exist at 1 atm in the solid, liquid, or vapor phase, depending on the temperature. Additionally, the values of these other properties of X have been determined: melting point 25. °C boiling point 55. °C enthalpy of fusion 9.00 kJ/mol enthalpy of 49.00 kJ/mol vaporization 2.00 g/cm (solid) density 37. J.Kmol 1 1 (solid) olo 1.70 g/mL (liquid) heat capacity 51. J·Kmol (liquid) -1 Ar 43. J-к "mol (vapor) You may also assume X behaves as an ideal gas in the vapor phase. Suppose a small sample of X at 0 °C is put into an evacuated flask and heated at a constant rate until 15.0 kJ/mol of heat has been added to the sample. Graph the temperature of the sample that would be observed during this experiment. 100 90- ? 80- 70 60 50 40 30 20 10 10 15 heat added (kJ/mol) temperature (*C)

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter9: Liquids And Solids

Section: Chapter Questions

Problem 20QAP

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Dichloromethane, CH2Cl2,is widely used as a degreaser and paint stripper. Its vapor pressure is 381.0 mm Hg at 21.9C and 465.8 mm Hg at 26.90C. Estimate (a) its heat of vaporization (Hvap). (b) its normal boiling point.
Consider the following data for xenon: Triple point: 121C, 280 torr Normal melting point: 112C Normal boiling point: 107C Which is more dense, Xe(s) or Xe(l)? How do the melting point and boiling point of xenon depend on pressure?
8.48 Why must the vapor pressure of a substance be measured only after dynamic equilibrium is established?
Equilibrium vapor pressures of benzene, C6H6, at various temperatures are given in the table. (a) What is the normal boiling point of benzene? (b) Plot these data so that you have a graph resembling the one in Figure 11.12. At what temperature does the liquid have an equilibrium vapor pressure of 250 mm Hg? At what temperature is the vapor pressure 650 mm Hg? (c) Calculate the molar enthalpy of vaporization for benzene using the ClausiusClapeyron equation.
Dry ice, CO2(s) , does not melt at atmospheric pressure. It sublimes at a temperature of 78 °C. What is the lowest pressure at which CO2(s) will melt to give CO2(l) ? At approximately what temperature will this occur? (See Figure 10.34 for the phase diagram.)
A pure substance X has the following properties: Mp=90C, increasing slightly as pressure increases; normal bp=120C; liquid vp=65mm Hg at 100C, 20 mm Hg at the triple point. (a) Draw a phase diagram for X. (b) Label solid, liquid, and vapor regions of the diagram. (c) What changes occur if, at a constant pressure of 100 mm Hg, the temperature is raised from 100C to 150C?
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.
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Given the following data about xenon, normalboilingpoint=108Cnormalmeltingpoint=112Ctriplepoint=121Cat281mmHgcriticalpoint=16.6Cat58atm (a) Construct an approximate phase diagram for xenon. (b) Estimate the vapor pressure of xenon at -115C. (c) Is the density of solid Xe larger than that for liquid Xe?
Given the following data about CO2: â€¢ triple point: -57C, 5.11 atm â€¢ critical point: 31C, 73 atm â€¢ sublimes at -78.5C, 1 atm â€¢ The solid is the denser phase. (a) Construct a simplified (not to scale) phase diagram for CO2. (b) Estimate the vapor pressure of CO2 at 0C. (c) At 10 atm pressure and -50C, is CO2 a liquid?
Carbon tetrachloride, CCl4, was once used as a dry cleaning solvent, but is no longer used because it is carcinogenic. At 57.8 C, the vapor pressure of CCl4 is 54.0 kPa, and its enthalpy of vaporization is 33.05 kJ/mol. Use this information to estimate the normal boiling point for CC14.
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?