Deck 11: Solutions: Properties and Behavior

Question 1

The interaction energy of LiF is -1.14 $\times$ 10^-18 J. What is the distance between the Li⁺ and F^- ions?

A)203 nm
B)203 pm
C)0.203 pm
D)494 pm
E)302 pm

Answer 1

203 pm

Question 2

Which of the following will require the greatest energy input to separate the ions?

A)MgI₂
B)MgF₂
C)MgCl₂
D)MgBr₂
E)NaCl

Answer 2

MgF₂

Question 3

Which of the following will have the largest cation-anion attraction?

A)NaF
B)NaCl
C)NaBr
D)NaI
E)CsCl

Answer 3

NaF

Question 4

Predict the relationship between the lattice energies (U) of KBr and CaO.

A)U_CaO > 4 U_KBr because the ionic charges are +2 and -2 and the distance between the ions is smaller.
B)U_CaO < 4 U_KBr because the ionic charges are +2 and -2 and the distance between the ions is larger..
C)U_CaO > 2 U_KBr because the ionic charges are +2 and -2 and the distance between the ions is smaller.
D)U_CaO < 4 U_KBr because the ionic charges are +2 and -2 and the distance between the ions is larger.
E)U_CaO and U_KBr are about the same because the larger ionic charge is compensated by the larger distance between the ions.

Question 5

Predict which of the following ionic compounds has the highest melting point.

A)NaF
B)KCl
C)RbCl
D)BeF₂
E)NaCl

Question 6

Coulomb's law states that the interaction energy between ions depends ________

A)only on the ionic charges.
B)only on the distance between the ions.
C)directly on both the ionic charges and the distance between the ions.
D)on the temperature.
E)directly on the ionic charges and inversely on the distance between the ions.

Question 7

Predict the relationship between the lattice energies (U) of KNO₃ and NaBr.

A)U_KNO3 > U_NaBr
B)U_KNO3 < U_NaBr
C)U_KNO3 > 2 U_NaBr
D)U_KNO3 < U_NaBr
E)U_KNO3 and U_NaBr are about the same.

Question 8

Rank the following compounds in order of increasing attraction between their ions: KBr, SrBr₂, and CsBr.

A)CsBr < KBr < SrBr₂
B)SrBr₂ < CsBr < KBr
C)KBr < SrBr₂ < CsBr
D)CsBr < SrBr₂ < KBr
E)SrBr₂ < KBr < CsBr

Question 9

Which arrangement below orders the cations from smallest to largest hydration energy? Smallest to largest means least negative hydration energy to most negative hydration energy.

A)Cs⁺ < K⁺< Ca²⁺ < Al³⁺
B)K⁺ < Cs⁺ < Ca²⁺ < Al³⁺
C)Al³⁺ < Ca²⁺< K⁺< Cs⁺
D)Al³⁺< Ca²⁺< Cs⁺< K⁺
E)K⁺< Cs⁺< Al³⁺< Ca²⁺

Question 10

Which of the following must be true if the dissolution of an ionic solid in water is exothermic?

A)The process requires energy.
B)The solubility will increase with increasing temperature.
C)The hydration energy exceeds the lattice energy.
D)The ions must have charges greater in magnitude than 1.
E)The change in enthalpy for this process is positive.

Question 11

Which of the following requires the smallest energy to separate the ions?

A)CaF₂
B)KF
C)NaF
D)MgF₂
E)LiCl

Question 12

Which of the following will have the largest lattice energy?

A)NaF
B)NaCl
C)NaBr
D)NaI
E)CsCl

Question 13

Arrange the three ionic compounds sodium chloride, magnesium chloride, and aluminum chloride in order of increasing melting point.

A)NaCl < MgCl₂ < AlCl₃
B)MgCl₂ < NaCl < AlCl₃
C)AlCl₃ < MgCl₂ < NaCl
D)AlCl₃ < NaCl < MgCl₂
E)NaCl < AlCl₃ < MgCl₂

Question 14

Ion interaction energies are determined by Coulomb's law: Which of the following compounds has an interaction energy = -3.83 $\times$ 10^-18 J?

A)NaCl (d = 294 pm)
B)MgS (d = 241 pm)
C)LiF (d = 189 pm)
D)CaO (d = 235 pm)
E)AlN (d = 185 pm)

Question 15

Which of the following ranks the compounds from lowest to highest lattice energy?

A)LiF < CaCl₂ < CaS < KBr
B)KBr < LiF < CaCl₂ < CaS
C)CaCl₂ < CaS < LiF < KBr
D)CaS < CaCl₂ < LiF < KBr
E)KBr < LiF < CaS < CaCl₂

Question 16

Which of the following must be true if the dissolution of an ionic solid in water is endothermic?

A)The change in enthalpy for this process is negative.
B)The process releases energy.
C)The hydration energy exceeds the lattice energy.
D)The ions have charges greater than 1 unit.
E)The solubility will increase with increasing temperature.

Question 17

Coulomb's law states that the energy of attraction between ions depends ________

A)only on the charge of the cation.
B)only on the charge of the anion.
C)directly on the distance between the ions.
D)on the charges of both ions.
E)on the temperature.

Question 18

Which statement A-D about ionic solids is not correct?

A)The enthalpy of hydration includes two terms: one for ion-dipole interactions and one for dipole-dipole interactions.
B)The melting point of an ionic solid increases as the lattice energy increases.
C)The enthalpy of solution consists of two terms: the lattice energy and the enthalpy of hydration.
D)The lattice energy depends directly on the product of ionic charges, inversely on the distance between the ions, and on the structure of the solid.
E)Statements A-D are all correct.

Question 19

Which arrangement below orders the cations from smallest to largest hydration energy? Smallest to largest means least negative hydration energy to most negative hydration energy.

A)Fe³⁺ < Mg²⁺ < Rb⁺ < Na⁺
B)Na⁺ < Rb⁺ < Mg²⁺< Fe³⁺
C)Fe³⁺< Mg²⁺< Na⁺ < Rb⁺
D)Rb⁺ < Na⁺ < Mg²⁺ < Fe³⁺
E)Na⁺ < Rb⁺ < Fe³⁺ < Mg²⁺

Question 20

Ion interaction energies are determined by Coulomb's law: Determine the energy of potassium chloride if the radius of the potassium ion is 133 pm and that of the chloride ion is 181 pm.

A)(-7.36 $\times$ 10^-19 J)
B)(-7.36 $\times$ 10^-22 J)
C)7.36 $\times$ 10^-19 J
D)1.74 $\times$ 10^-18 J
E)(-7.36 $\times$ 10^-25 J)

Question 21

Which of the following requires the smallest energy to separate the ions?

A)CaF₂
B)KF
C)NaF
D)MgF₂
E)LiF

Question 22

Which of the following ionic compounds would you predict to have the lowest solubility in water?

A)MgF₂
B)MgCl₂
C)CaBr₂
D)SrI₂
E)BaI₂

Question 23

Why would you expect or predict sodium fluoride to have the lowest solubility in water compared to the other sodium halide salts?

A)Fluoride has the largest (most negative) enthalpy of hydration of all the halide ions.
B)Fluoride has the smallest (least negative) enthalpy of hydration of all the halide ions.
C)Sodium fluoride has the largest (most negative) lattice energy of all the sodium halides.
D)Sodium fluoride has the smallest molar mass of all the sodium halides.
E)Fluoride is the most basic of all the halide ions and forms HF in aqueous solution.

Question 24

In the following Born-Haber cycle for the formation of sodium chloride from its elements, which step (A-E) corresponds to the ionization energy of one of the reactants?

A)A
B)B
C)C
D)D
E)E

Question 25

In the following Born-Haber cycle for the formation of sodium chloride from its elements, which step (A-E) corresponds to the electron affinity of one of the intermediate species?

A)A
B)B
C)C
D)D
E)E

Question 26

Which of the following will have the smallest lattice energy?

A)LiCl
B)K₂O
C)MgBr₂
D)Al₂S₃
E)CsI

Question 27

Which of the following is not typically needed to calculate the lattice energy of an ionic compound?

A)enthalpy of vaporization
B)bond enthalpy
C)enthalpy of solution
D)electron affinity
E)ionization energy

Question 28

Which of the following ionic compounds would you predict to have the highest solubility in water?

A)MgF₂
B)MgCl₂
C)CaBr₂
D)SrI₂
E)BaI₂

Question 29

Which one of the ionic compounds below would you expect to have the smallest (least negative) lattice energy?

A)MgF₂
B)MgCl₂
C)MgBr₂
D)MgI₂
E)CaI₂

Question 30

Calculate the lattice energy of magnesium chloride from the following data: First ionization energy of Mg: 738 kJ/mol
Second ionization energy of Mg: 1,451 kJ/mol
Electron affinity of Cl: -349 kJ/mol
Energy to vaporize Mg: 147.1 kJ/mol
Cl₂ bond energy: 243 kJ/mol
Energy change for the reaction:

A)1,246 kJ/mol
B)(-779 kJ/mol)
C)(-2,492 kJ/mol)
D)2,492 kJ/mol
E)(-1,246 kJ/mol)

Question 31

Which one of the ionic compounds below would you expect to have the smallest (least negative) lattice energy?

A)MgO
B)CaO
C)SrO
D)BaO
E)BeO

Question 32

Which one of the ionic compounds below would you expect to have the largest (most negative) lattice energy?

A)MgF₂
B)MgCl₂
C)MgBr₂
D)MgI₂
E)CaI₂

Question 33

Which one of the ionic compounds below would you expect to have the largest (most negative) lattice energy?

A)MgO
B)CaO
C)SrO
D)BaO
E)BeO

Question 34

Which of the following compounds has the largest melting point?

A)NaF
B)KCl
C)RbCl
D)BeF₂
E)NaCl

Question 35

Which listing of ionic compounds is in order of increasing melting point?

A)NaF < MgF₂ < AlF₃
B)MgF₂ < NaF < AlF₃
C)AlF₃ < MgF₂ < NaF
D)AlF₃ < NaF < MgF₂
E)NaF < AlF₃ < MgF₂

Question 36

Which of the following will require the greatest energy input to separate the ions?

A)MgI₂
B)MgF₂
C)MgCl₂
D)MgBr₂
E)NaCl

Question 37

Which of the following compounds has the lowest melting point?

A)NaF
B)KCl
C)RbCl
D)BeF₂
E)NaCl

Question 38

In the following Born-Haber cycle for the formation of sodium chloride from its elements, which step (A-E) corresponds to a molar heat of sublimation for one of the reactants?

A)A
B)B
C)C
D)D
E)E

Question 39

In the following Born-Haber cycle for the formation of sodium chloride from its elements, which step (A-E) corresponds to the lattice energy for NaCl?

A)A
B)B
C)C
D)D
E)E

Question 40

Calculate the lattice energy of sodium fluoride from the following data: Ionization energy of Na: 496 kJ/mol
Electron affinity of F: -328 kJ/mol
Energy to vaporize Na: 108 kJ/mol
F₂ bond energy: 160 kJ/mol
Energy change for the reaction:

A)931 kJ/mol
B)(-931 kJ/mol)
C)(-1,011 kJ/mol)
D)1,011 kJ/mol
E)(-851 kJ/mol)

Question 41

Which of the solutions shown here will have the lowest vapor pressure? White circles indicate solvent molecules; black circles indicate molecules of a nonvolatile solute.

A)
B)
C)
D)

Question 42

Which graph best describes how the vapor pressure of a solution varies according to Raoult's law as a nonvolatile solute is added to a liquid? The vapor pressure of the solution is plotted on the y-axis, and the mole fraction of solute is plotted on the x-axis. The origin (0, 0) is not necessarily located where the axes cross.

A)I
B)II
C)III
D)IV

Question 43

In the diagram below, one beaker contains pure water and the other contains an equal volume of seawater. Seawater has various salts dissolved in it. The beakers are sitting in a totally enclosed chamber, and the outside temperature and pressure are held constant. Identify the statements below about this situation that are not correct.
I. Water will be transferred from the pure water beaker to the seawater beaker.
II. Water will be transferred from the seawater beaker to the pure water beaker.
III.The vapor pressure of the pure water is higher than the vapor pressure of the seawater.
IV. Pure water evaporates at a faster rate than seawater.
V. Water in the gas phase condenses into both beakers at the same rate.

A)II only
B)II and V
C)II, IV, and V
D)II, III, and IV
E)I, III, and IV

Question 44

Which statement about the vapor pressure of a liquid is not correct?

A)Temperature, solute concentration, and solvent identity all play roles in determining the vapor pressure above a solution.
B)The mole fraction of the solvent is used to calculate the vapor pressure above a solution.
C)The vapor pressure of a solution is not related to the vapor pressure of the pure solvent.
D)In ideal solutions that obey Raoult's law, solute and solvent molecules both experience similar intermolecular forces.
E)Vapor pressure of a solution is a colligative property, which means pressure depends on the concentration of a solute, not its identity.

Question 45

Indicate which aqueous solution has the highest vapor pressure.

A)0.1 M KCl
B)0.2 M Na₂CO₃
C)0.2 M NaCl
D)0.1 M MgCl₂
E)0.2 M MgCl₂

Question 46

A solution is prepared by adding 1.50 mol glucose, which is not volatile, to 3.50 mol diethyl ether. What is the vapor pressure of this solution at 25 ^$\circ$ C given that the vapor pressure of pure diethyl ether is 23.8 torr?

A)7.00 torr
B)16.7 torr
C)10.2 torr
D)7.14 torr
E)34.0 torr

Question 47

Which of the solutions shown here will have the highest vapor pressure? White circles indicate solvent molecules; black circles indicate molecules of a nonvolatile solute.

A)
B)
C)
D)

Question 48

Indicate which aqueous solution has the lowest vapor pressure.

A)0.25 M LiBr
B)0.2 M K₃PO₄
C)0.3 M Cs₂CO₃
D)0.1 M CaI₂
E)0.4 M AgNO₃

Question 49

Which statement about the vapor pressure of a liquid is not correct?

A)The vapor pressure increases with increasing temperature because more molecules have sufficient energy to overcome the attractive forces that hold them in the liquid.
B)The vapor pressure decreases with increasing strength of intermolecular interactions.
C)The pressure at which the rate of molecules evaporating equals the rate of molecules condensing is called the vapor pressure.
D)Adding a nonvolatile solute to a liquid increases the vapor pressure.
E)The enthalpy of vaporization determines how sensitive the vapor pressure of a substance is to a change in temperature.

Question 50

Which statement below regarding vapor pressure is not correct?

A)Vapor pressure is an intensive property.
B)The substance with the stronger intermolecular forces has the lower vapor pressure.
C)Vapor pressure increases with increasing temperature.
D)Pure water has a higher vapor pressure at a given temperature than seawater.
E)A nonvolatile solute increases the vapor pressure of the solvent.

Question 51

Which of the following is needed to calculate the lattice energy of an ionic compound?

A)enthalpy of solution
B)enthalpy of combustion
C)specific heat
D)ionization energy
E)enthalpy of solvation

Question 52

Indicate which aqueous solution has the lowest vapor pressure.

A)0.1 M KCl
B)0.1 M Na₂CO₃
C)0.2 M NaCl
D)0.1 M MgCl₂
E)0.2 M MgCl₂

Question 53

Which graph best describes how the vapor pressure of a substance varies with temperature according to the Clausius-Clapeyron equation? ln(P) is plotted on the y-axis, and 1/T is plotted on the x-axis. The origin (0, 0) is not necessarily located where the axes cross.

A)I
B)II
C)III
D)IV

Question 54

Which intermolecular interactions are likely to result in the lowest vapor pressure of a substance?

A)dispersion interactions
B)dipole-dipole interactions
C)hydrogen bonds
D)ion-dipole interactions
E)ion-ion interactions

Question 55

A solution contains 6.50 mol water, 0.300 mol sucrose, and 0.200 mol glucose. The solutes are nonvolatile. What is the vapor pressure of the solution at 35 ^$\circ$ C given that the vapor pressure of water is 42.2 torr?

A)35.0 torr
B)36.0 torr
C)37.0 torr
D)39.2 torr
E)39.0 torr

Question 56

Which statement about how the vapor pressure (P) of a liquid depends on temperature is correct?

A)The larger the enthalpy of vaporization, the smaller the change in vapor pressure for a given change in temperature.
B)A graph of P versus 1/T is linear with a slope $\Delta$ H_vap /R.
C)The smaller the intermolecular interactions, the greater the change in vapor pressure for a given change in temperature.
D)A graph of ln(P) versus T is linear with a slope $\Delta$ H_vap /R.
E)A graph of ln(P) versus 1/T is linear with a slope $\Delta$ H_vap /R.

Question 57

Which intermolecular interactions are likely to result in the highest vapor pressure of a substance?

A)dispersion interactions
B)dipole-dipole interactions
C)hydrogen bonds
D)ion-dipole interactions
E)ion-ion interactions

Question 58

A solution is prepared by adding 0.250 mol napthalene, which is not volatile, to 2.25 mol diethyl ether. What is the vapor pressure of this solution at 25 ^$\circ$ C given that the vapor pressure of pure diethyl ether is 532 torr?

A)53.2 torr
B)59.1 torr
C)473 torr
D)479 torr
E)591 torr

Question 59

What is the vapor pressure of an aqueous solution that has a solute mol fraction of $\chi$ = 0.100 ? The vapor pressure of water is 25.756 mm Hg at 25 ^$\circ$ C.

A)23.2 mm Hg
B)2.58 mm Hg
C)25.8 mm Hg
D)0.900 mm Hg
E)22.3 mm Hg

Question 60

Determine the energy change for the reaction from the following data: Lattice energy of LiCl = -861 kJ/mol
Energy to vaporize Li = 159 kJ/mol
Ionization energy of Li = 520 kJ/mol
Cl₂ bond energy: 240 kJ/mol
Electron affinity of Cl: -349 kJ/mol

A)(-411 kJ/mol)
B)(-528 kJ/mol)
C)311 kJ/mol
D)(-861 kJ/mol)
E)(-291 kJ/mol)

Question 61

At 25 ^$\circ$ C, the vapor pressure of pure water is 25.756 mm Hg. What is the vapor pressure of water in a 0.500 m solution of sodium chloride?

A)25.52 mm Hg
B)0.2301 mm Hg
C)0.4602 mm Hg
D)25.35 mm Hg
E)12.88 mm Hg

Question 62

How many moles of solute are there in a 0.155 m glucose solution prepared with 50.0 kg of water?

A)15.5 mol
B)15.0 mol
C)0.155 mol
D)31.0 mol
E)7.75 mol

Question 63

What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL?

A)0.340 m
B)3.39 m
C)3.27 m
D)3.74 m
E)2.96 m

Question 64

A medical company separates methanol (CH₃OH)) and ethanol (CH₃CH₂OH) by distillation. In one run, the starting solution was 25% methanol and 75% ethanol by mass at 25 ^$\circ$ C. In the liquid, the mole ratio of methanol to ethanol was ________, and in the vapor it was ________. The vapor pressures for methanol and ethanol at this temperature are 92 torr and 45 torr, respectively.

A)0.48; 2.0
B)2.0; 0.48
C)0.33; 2.0
D)0.48; 0.33
E)2.3; 0.55

Question 65

The molality of a solution is defined as ________

A)moles of solute per liter of solution.
B)grams of solute per liter of solution.
C)moles of solute per kilogram of solution.
D)moles of solute per kilogram of solvent.
E)grams of solute per kilogram of solvent.

Question 66

The concentration unit of molality is symbolized as ________

A)M.
B)m.
C)M..
D)mol.
E)mo.

Question 67

Indicate which aqueous solution has the fastest evaporation rate.

A)0.10 M CaCO₃
B)0.20 M NaNO₃
C)0.15 M KBr
D)0.30 M Li₂SO₄
E)0.10 M MgCl₂

Question 68

What physical property is used to separate the hydrocarbon components in petroleum (crude oil)?

A)melting point
B)density
C)boiling point
D)molar mass
E)viscosity

Question 69

Which graph best describes how the vapor pressure of a solution varies according to Raoult's law as a nonvolatile solute is added to a liquid? The vapor pressure of the solution is plotted on the y-axis, and the mole fraction of solvent is plotted on the x-axis. The origin (0, 0) is not necessarily located where the axes cross.

A)I
B)II
C)III
D)IV

Question 70

The vapor pressure of an aqueous solution is found to be 24.9 mm Hg at 25 ^$\circ$ C. What is the mole fraction of solute in this solution? The vapor pressure of water is 25.756 mm Hg at 25 ^$\circ$ C.

A)0.967
B)0.0332
C)1.03
D)0.0344
E)0.976

Question 71

Which of the following is a colligative property?
I. osmotic pressure
II. molar mass
III. density
IV. freezing point depression
V. boiling point

A)I, II, IV, and V only
B)I and IV only
C)II and IV only
D)II, III, and V only
E)I, II, and V only

Question 72

A colligative property does not depend on ________

A)the concentration of solute.
B)the type of solvent.
C)the volume of solution.
D)whether a solute is a strong or weak electrolyte.
E)the identity of the solute present.

Question 73

Calculate the molality of a solution containing 0.755 mol glucose and 1.75 kg of water.

A)0.875 m
B)0.583 m
C)0.431 m
D)580 m
E)0.850 m

Question 74

Which statement regarding the fractional distillation of two substances is not correct?

A)The substance with the lower boiling point has a higher concentration in the vapor than in the liquid.
B)The boiling point of the mixture is not constant, changing as the distillation progresses.
C)The substance with the higher vapor pressure has a higher concentration in the vapor than in the liquid.
D)The mole ratio of the two substances in the vapor is not the same as it is in the liquid.
E)When the vapor at any stage of the distillation is condensed, the resulting distillate has the same composition as the original mixture of the two substances.

Question 75

A solution is prepared by mixing 75 g of benzene (C₆H₆) with 25 g of toluene (C₇H₈). Use the following data to determine the vapor pressure of this solution at 20 ^$\circ$ C.

A)63 torr
B)49 torr
C)87 torr
D)35 torr
E)71 torr

Question 76

Isopropyl alcohol has a boiling point of 82.3 ^$\circ$ C. Solutions of isopropyl alcohol in water have normal boiling points less than 100 ^$\circ$ C. Is this observation consistent with the following equation? Explain. $\Delta$ T_b = iK_bm

A)No, boiling point elevation only pertains to ionic solutes.
B)No, boiling point elevation only pertains to nonvolatile solutes.
C)Yes, boiling point depression occurs for all solutions.
D)Yes, the boiling point depression constant for isopropyl alcohol is large.
E)No, isopropyl alcohol can hydrogen bond with water.

Question 77

Indicate which aqueous solution has the slowest evaporation rate.

A)0.1 M KCl
B)0.2 M Na₂CO₃
C)0.2 M NaCl
D)0.1 M MgCl₂
E)0.1 M NaBr

Question 78

A petroleum company separates benzene (78 g/mol) and n-octane (114 g/mol) by distillation. In one run, the starting solution was 15% benzene and 85% n-octane by mass at 25 ^$\circ$ C. In the liquid, the mole ratio of benzene to n-octane was ________, and in the vapor it was ________. The vapor pressures for benzene and n-octane at this temperature are 11 torr and 95 torr, respectively.

A)0.26; 0.12
B)0.18; 0.12
C)0.80; 0.20
D)0.26; 0.18
E)0.31; 0.23

Question 79

Calculate the molality of a solution containing 0.355 mol sodium hydrogen carbonate (baking soda) and 245 g of water.

A)1.45 m
B)1.12 $\times$ 10^-2 m
C)2.11 m
D)1.12 $\times$ 10^-3 m
E)0.0211 m

Question 80

A solution is prepared by mixing 50 g of methanol (CH₃OH) with 50 g of ethanol (CH₃CH₂OH). Use the following data to determine the vapor pressure of this solution at 20 ^$\circ$ C.

A)69 torr
B)57 torr
C)80 torr
D)73 torr
E)83 torr