Name: Chemistry
Author: McMurry
ISBN: 9781292336145

Ch.11 - Liquids & Phase Changes

뒤로

모든 교과서

McMurry 8th Edition

Ch.11 - Liquids & Phase Changes

문제 15

Assume that you have a liquid in a cylinder equipped with a movable piston. There is no air in the cylinder, the volume of space above the liquid is 200 mL, and the equilibrium vapor pressure above the liquid is 28.0 mm Hg. What is the equilibrium pressure above the liquid when the volume of space is decreased from 200 mL to 100 mL at constant temperature?

문제 18

A phase diagram for a substance that exhibits the liquid crystalline state is shown. (b) If the substance is at a temperature and pressure repre- sented by point 1 and the temperature is increased until the phase changes, what is the phase transition? Describe how the ordering of molecules changes, and propose a reason for the change.

문제 19

The following compound undergoes a phase transition from the solid to the smectic liquid crystal phase at 121 °C. Upon further heating, the compound undergoes another transition to liquid phase at 131 °C.

(a) Which image represents the arrangement of molecules at 125 °C?

문제 21

Water flows quickly through the narrow neck of a bottle, but maple syrup flows sluggishly. Is this different behavior due to a difference in viscosity or in surface tension for the liquids?

문제 22

Predict which substance in each pair has the highest surface tension. (a) CCl4 or CH2Br2

문제 23a

Predict which substance in each pair has the highest viscosity. (a) Hexane 1CH3CH2CH2CH2CH2CH32 or 1-hexanol 1CH3CH2CH2CH2CH2CH2OH2

문제 23b

Predict which substance in each pair has the highest viscosity. (b) Pentane or neopentane

문제 24

The chemical structure for oleic acid, the primary component of olive oil, is shown. Explain why olive oil has a higher vis- cosity than water.

문제 25

The viscosity of water at 20 °C is 1.00 * 10-3 1N • s>m2 2 higher than dimethyl sulfide 31CH322 S4 2.8 * 10-4 1N • s>m2 2. Explain the difference in viscosity based on chemical structure.

문제 27

Assume that you have a sample of gas at 350 K in a sealed container, as represented in (a). Which of the drawings (b)–(d) represents the gas after the temperature is lowered from 350 K to 150 K? The boiling point of the gas is 90 K.

문제 29

What is the vapor pressure of SiCl4 in mm Hg at 30.0 °C? (See Problem 11.27.)

문제 30

Dichloromethane, CH2Cl2, is an organic solvent used for removing caffeine from coffee beans. The following table gives the vapor pressure of dichloromethane at various tem- peratures. Fill in the rest of the table, and use the data to plot curves of Pvap versus T and ln Pvap versus 1/T.

문제 31

The following diagram shows a close-up view of part of the vapor-pressure curves for a solvent (red curve) and a solution of the solvent with a second liquid (green curve). Is the second liquid more volatile or less volatile than the solvent?

문제 32

The following phase diagram shows part of the liquid–vapor phase-transition boundaries for two solutions of equal con- centration, one containing a nonvolatile solute and the other containing a volatile solute whose vapor pressure at a given temperature is approximately half that of the pure solvent.

(d) Based on your drawing, what is the approximate normal boiling point of the pure solvent?

문제 34

Choose any two temperatures and corresponding vapor pressures in the table given in Problem 11.30, and use those values to calculate ΔHvap for dichloromethane in kJ/mol. How does the value you calculated compare to the value you read from your plot in Problem 11.32?

문제 35

The dipole moment of methanol is m = 1.70 D. Use arrows to indicate the direction in which electrons are displaced.

문제 36

Dichlorodifluoromethane, CCl2F2, one of the chlorofluo- rocarbon refrigerants responsible for destroying part of the Earth's ozone layer, has Pvap = 40.0 mm Hg at -81.6 °C and Pvap = 400 mm Hg at -43.9 °C. What is the normal boiling point of CCl2F2 in °C?

문제 37

Two dichloroethylene molecules with the same chemical formula 1C2H2Cl22, but different arrangements of atoms are shown.

문제 39

Why is the heat of sublimation, ΔHsubl, equal to the sum of ΔHvap and ΔHfusion at the same temperature?

문제 40

Naphthalene, better known as 'mothballs,' has bp = 218 °C and ΔH_vap = 43.3 kJ>mol. What is the entropy of vaporization, ΔS_vap in J/(K mol) for naphthalene?

문제 44

Mercury has mp = -38.8 °C and bp = 356.6 °C. What,if any, phase changes take place under the following condi-tions at 1.0 atm pressure? (a) The temperature of a sample is raised from -30 °C to 365 °C.

문제 46

How much energy in kilojoules is needed to heat 5.00 g of ice from -11.0 °C to °30.0 °C? The heat of fusion of water is 6.01 kJ>mol, and the m# olar heat capacity is 36.01 kJ>mol for ice and 75.4 J/K mol2 for liquid water

문제 49

How much energy in kilojoules is released when 25.0 g of ethanol vapor at 93.0 °C is cooled to -11.0 °C? Ethanol has mp = -114.1 °C, bp = 78.3 °C, ΔHvap = 38.56 kJ>mol, and ΔHfusio#n = 4.93 kJ>mol. The molar heat#capacity is 112.3 J>1K mol2 for the liquid and 65.6 J>1K vapor.

문제 1

문제 2

문제 6

문제 10

문제 11

문제 13

문제 14