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 Clausius–Clapeyron equation.
(a)
Interpretation:
The normal boiling point of benzene has to be determined.
Concept Introduction:
Boiling point: It is the temperature at which liquid converts to vapor. At boiling point the vapor pressure of liquid and the pressure of the surroundings are equal.
Normal boiling point: When the external pressure is
Answer to Problem 21PS
The normal boiling point of benzene is
Explanation of Solution
The normal boiling point of benzene is calculated
Given:
Normal boiling point is the temperature when the external pressure is
From the given data it is clear that the temperature at which the pressure is
Thus the normal boiling point of benzene is
(b)
Interpretation:
The temperature versus vapor pressure graph should be plotted. The temperatures at which the liquid has vapour pressures of
Concept Introduction:
Vapor pressure is nothing but the pressure of a vapor in contact with its liquid or solid form.
When a liquid and vapor are in equilibrium the pressure exerted by the vapor is called the equilibrium vapor pressure
Answer to Problem 21PS
The temperatures at which liquid have a vapour pressures of
Explanation of Solution
Given,
The temperatures at which liquid have a vapour pressures of
Using the given data we can plot the graph of
From the graph we can find the approximate temperatures at which the pressures are
Therefore,
The temperature at which the pressure is
(c)
Interpretation:
The molar enthalpy of vaporization using Clausius-Clapeyron has to be determined
Concept Introduction:
Clausius-Clapeyron equation:
From this relationship we can calculate the molar enthalpy of vaporization by knowing the corresponding temperature and pressure values.
If we have pressures at two different temperatures, then enthalpy of vaporization can be calculated by
Answer to Problem 21PS
The molar enthalpy of vaporization of is
Explanation of Solution
The molar enthalpy of vaporization is calculated using the given data,
Given:
Clausius-Clapeyron equation is,
Substituting the values
The molar enthalpy of vaporization of is
Want to see more full solutions like this?
Chapter 11 Solutions
Chemistry & Chemical Reactivity
Additional Science Textbook Solutions
General, Organic, and Biological Chemistry (3rd Edition)
Elementary Principles of Chemical Processes, Binder Ready Version
Chemistry: The Central Science (14th Edition)
General Chemistry: Atoms First
- The vapor pressure of ethanol, C2H5OH, at 50.0 C is 233 mmHg, and its normal boiling point at 1 atm is 78.3 C. Calculate the vapH of ethanol.arrow_forward5-106 The normal boiling point of hexane, C6H14, is 69°C, and that of pentane, C5H12, is 36°C. Predict which of these compounds has a higher vapor pressure at 20°C.arrow_forwardUse Figure 11.7 to estimate the boiling point of carbon tetrachloride, CCl4, under an external pressure of 250 mmHg.arrow_forward
- Use Figure 11.7 to estimate the boiling point of diethyl ether, (C2H5)2O, under an external pressure of 470 mmHg.arrow_forwardChloroform, CHCl3, has a normal boiling point of 61C. Its vapor pressure at 43C is 0.526 atm. What is the concentration (in g/L) of CHCl3 when it saturates the air at 27C?arrow_forwardDiethyl ether (CH3CH2OCH2CH3) was one of the first chemicals used as an anesthetic. At 34.6C, diethyl ether has a vapor pressure of 760. torr, and at 17.9C, it has a vapor pressure of 400. torr. What is the H of vaporization for diethyl ether?arrow_forward
- A 1.50-g sample of methanol (CH3OH) is placed in an evacuated 1.00-L container at 30 C. (a) Calculate the pressure in the container if all of the methanol is vaporized. (Assume the ideal gas law, PV = nRT.) (b) The vapor pressure of methanol at 30 C is 158 torr. What mass of methanol actually evaporates? Is liquid in equilibrium with vapor in the vessel?arrow_forwardConsider 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.arrow_forwardA 5.4-L closed vessel is filled with 0.46 g of liquid ethanol. This ethanol containing closed vessel is placed in the freezer and reaches the vapor pressure of 6.65 torr at -11 C. (i) Is there any liquid ethanol remained in the closed vessel when the container is removed and warmed to the temperature of 25 C? Justify your answer. (ii) How many grams of liquid ethanol remained in the vessel at 2.0 C? The enthalpy changes of vaporization, AH,vap of ethanol is 40.5 kJ/mol. The molar mass of ethanol is 46.07 g/mol.arrow_forward
- 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 0.5329 atm, and its enthalpy of vaporization is 33.05 kJ/mol. Use this information to estimate the normal boiling pointarrow_forwardMercury (Hg) vapor is toxic and readily absorbed from the lungs. At 20.∘C, mercury (ΔHvap = 59.1 kJ/mol) has a vapor pressure of 1.20 x 10-3 torr, which is high enough to be hazardous. To reduce the danger to workers in processing plants, Hg is cooled to lower its vapor pressure. At what temperature would the vapor pressure of Hg be at the safer level of 5.0 x 10-5 torr?arrow_forwardFor acetone (CH3)2CO, the normal boiling point is 56.5 °C and the enthalpy of vaporization is 31.3 kJ/mol. What is the vapor pressure of acetone at 25.0 °C?arrow_forward
- Chemistry & Chemical ReactivityChemistryISBN:9781337399074Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningGeneral Chemistry - Standalone book (MindTap Cour...ChemistryISBN:9781305580343Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; DarrellPublisher:Cengage Learning
- ChemistryChemistryISBN:9781305957404Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistry: Principles and PracticeChemistryISBN:9780534420123Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward MercerPublisher:Cengage Learning