Deck 12: Solutions and Their Properties

Question 1

For which case would ΔH_soln be expected to be negative?

A)if solute-solute interactions are much greater than solvent-solvent and solute-solvent interactions
B)if solvent-solvent interactions are much greater than solute-solvent and solute-solute interactions
C)if solute-solvent interactions are much greater than solvent-solvent and solute-solute interactions
D)if solute-solvent interactions are the same as solvent-solvent and solute-solute interactions

Answer 1

if solute-solvent interactions are much greater than solvent-solvent and solute-solute interactions

Question 2

The change in the Gibbs free energy for dissolving more solute in a supersaturated solution is

A)negative.
B)zero.
C)positive.
D)positive at low temperatures and negative at high temperatures.

Answer 2

positive.

Question 3

The change in the Gibbs free energy for dissolving solute in a saturated solution is

A)negative.
B)zero.
C)positive.
D)positive at low temperatures and negative at high temperatures.

Answer 3

zero.

Question 4

For the process of dissolving a solid in a liquid,which of the following statements is true?

A)ΔH_soln is always negative and ΔS_soln is usually positive.
B)ΔH_soln is always positive and ΔS_soln is usually negative.
C)ΔH_soln is either positive or negative and ΔS_soln is usually positive.
D)ΔH_soln is either positive or negative and ΔS_soln is usually negative.

Question 5

Commercial cold packs often contain solid NH₄NO₃ and a pouch of water.The temperature of the pack drops as the NH₄NO₃ dissolves in water.Therefore,for the dissolving of NH₄NO₃ in water,

A)ΔH_soln is negative and ΔS_soln may be negative or positive.
B)ΔH_soln is negative and Δ_Ssoln is positive.
C)ΔH_soln is positive and ΔS_soln may be negative or positive.
D)ΔH_soln is positive and ΔS_soln is positive.

Question 6

When two similar liquids mix to form a solution,the entropy of solution (ΔS_soln)is expected to be

A)negative.
B)zero.
C)positive.
D)negative at low temperatures but positive at high temperatures.

Question 7

Which of the following mixtures have components which can be separated by filtration?

A)colloids
B)solutions
C)suspensions
D)all of these

Question 8

When an ionic solute dissolves in water to form an unsaturated solution,the free energy change (ΔG_soln)is

A)negative.
B)zero.
C)positive.
D)either A or C,depending on the ionic compound.

Question 9

Although there are exceptions,which is most likely to be true for the dissolving of a solid in a liquid?

A)ΔH_soln is positive.
B)ΔH_soln is negative.
C)ΔS_soln is positive.
D)ΔS_soln is negative.

Question 10

Which of the following should most favor the solubility of an ionic solid in water?

A)a low lattice energy for the solid and a low hydration energy for its ions
B)a low lattice energy for the solid and a high hydration energy for its ions
C)a high lattice energy for the solid and a low hydration energy for its ions
D)a high lattice energy for the solid and a high hydration energy for its ions

Question 11

The rubbing alcohol sold in drug stores often is composed of 70% isopropyl alcohol and 30% water.In this solution

A)isopropyl alcohol is the solvent.
B)water is the solvent.
C)both water and isopropyl alcohol are solvents.
D)neither water nor isopropyl alcohol is a solvent.

Question 12

One reason ionic compounds do not dissolve well in nonpolar solvents is that

A)ion-dipole interactions are too large for effective solvation to occur.
B)ion-solvent interactions are not strong enough to solvate the ions in solution.
C)not all cations and anions have the same magnitude of charge and therefore do not form neutral ion pairs.
D)there are no forces of attraction between ions and nonpolar molecules.

Question 13

When a particular solid begins to dissolve in water,the temperature rises dramatically.For the dissolving of this solid in pure water

A)ΔH_soln is always negative and ΔS_soln may be negative or positive.
B)ΔH_soln is always negative and ΔS_soln is always positive.
C)ΔH_soln is always positive and ΔS_soln may be negative or positive.
D)ΔH_soln is always positive and ΔS_soln is always positive.

Question 14

For a liquid solution made by dissolving a solid or a gas in a liquid,the

A)liquid is the solute.
B)liquid is the solvent.
C)solute is the component present in the greatest amount.
D)solvent is the component present in the greatest amount.

Question 15

Iodine,I₂(s),is more soluble in dichloromethane,CH₂Cl₂(l),than in water because

A)both iodine and dichloromethane have strong ion-dipole interactions.
B)the dipole-dipole forces in dichloromethane are much stronger than the dispersion forces in iodine.
C)the intermolecular forces are similar in both iodine and dichloromethane.
D)iodine is polar and dichloromethane has a large number of hydrogen bonds.

Question 16

In most liquid solutions,the component present in the larger amount is called the

A)dispersed medium.
B)emulsifying agent.
C)solute.
D)solvent.

Question 17

Formaldehyde is a carcinogenic volatile organic compound with a permissible exposure level of 0.75 ppm.At this level,how many grams of formaldehyde are permissible in a 6.0-L breath of air having a density of 1.2 kg/m³?

A)3.8 × 10^-2 g formaldehyde
B)5.4 × 10^-6 g formaldehyde
C)3.8 g formaldehyde
D)5.4 g formaldehyde

Question 18

Which should be least soluble in water?

A)

B)

C)

D)

Question 19

Which cation in each set is expected to have the larger (more negative)hydration energy? I.Mg²⁺ or Ca²⁺
II.Li⁺ or Al³⁺

A)Mg²⁺ in set I and Li⁺ in set II
B)Mg²⁺ in set I and Al³⁺ in set II
C)Ca²⁺ in set I and Li⁺ in set II
D)Ca²⁺ in set I and Al³⁺ in set II

Question 20

Most gases become less soluble in water as the temperature increases.What can be concluded about the signs of ΔH_soln and ΔS_soln in this case?

A)ΔH_soln is negative and ΔS_soln is negative.
B)ΔH_soln is negative and ΔS_soln is positive.
C)ΔH_soln is positive and ΔS_soln is negative.
D)ΔH_soln is positive and ΔS_soln is positive.

Question 21

What is the weight percent of vitamin C in a solution made by dissolving 8.00 g of vitamin C,C₆H₈O₆,in 55.0 g of water?

A)87.3%
B)14.5%
C)12.7%
D)85.5%

Question 22

To make a 3.0 M solution,one could take 3.00 moles of solute and add

A)1.00 L of solvent.
B)1.00 kg of solvent.
C)enough solvent to make 1.00 L of solution.
D)enough solvent to make 1.00 kg of solution.

Question 23

How many grams of KBr are required to make 850.mL of a 0.115 M KBr solution?

A)0.0978 g
B)85.9 g
C)11.6 g
D)13.7 g

Question 24

What volume of 0.716 M KBr solution is needed to provide 13.0 g of KBr?

A)6.55 mL
B)9.31 mL
C)18.5 mL
D)153 mL

Question 25

What is the mole fraction of ethanol in a solution made by dissolving 25.0 g of ethanol,C₂H₅OH,in 53.6 g of water?

A)0.154
B)0.846
C)0.214
D)0.272

Question 26

A solution is prepared by dissolving 17.75 g sulfuric acid,H₂SO₄,in enough water to make 100.0 mL of solution.If the density of the solution is 1.1094 g/mL,what is the molarity?

A)0.1775 M H₂SO₄
B)0.1810 M H₂SO₄
C)1.810 M H₂SO₄
D)1.940 M H₂SO₄

Question 27

A solution is prepared by dissolving 17.75 g sulfuric acid,H₂SO₄,in enough water to make 100.0 mL of solution.If the density of the solution is 1.1094 g/mL,what is the mole fraction H₂SO₄ in the solution?

A)0.0181
B)0.0338
C)0.0350
D)19.0

Question 28

What is the mole fraction of oxygen in a gas mixture that is 40.0% oxygen and 60.0% nitrogen by volume?

A)0.632
B)0.368
C)0.400
D)0.600

Question 29

A solution is prepared by dissolving 171 g of CdCl₂ in enough water to make 250.0 mL of solution.If the density of the solution is 1.556 g/mL,what is the molarity of the solution?

A)0.440 M
B)0.684 M
C)0.933 M
D)3.73 M

Question 30

What is the mole fraction of I₂ in a solution made by dissolving 27.8 g of I₂ in 260 g of hexane,C₆H₁₄?

A)0.0350
B)0.965
C)1.03
D)28.57

Question 31

What is the weight percent of a caffeine solution made by dissolving 4.00 g of caffeine,C₈H₁₀N₄O₂,in 75.0 g of benzene,C₆H₆?

A)0.0506%
B)0.0533%
C)5.06%
D)5.33%

Question 32

What molality of pentane is obtained by dissolving 50.0 g pentane,C₅H₁₂,in 245.0 g hexane,C₆H₁₄?

A)0.200 m
B)0.240 m
C)2.83 m
D)200.m

Question 33

How much water must be added to 42.0 g of CaCl₂ to produce a solution that is 40.0 wt% CaCl₂?

A)56.7 g
B)63.0 g
C)16.8 g
D)120 g

Question 34

To make a 3.00 m solution,one could take 3.00 moles of solute and add

A)1.00 L of solvent.
B)1.00 kg of solvent.
C)enough solvent to make 1.00 L of solution.
D)enough solvent to make 1.00 kg of solution.

Question 35

What volume of 3.00 M CH₃OH solution is needed to provide 0.500 mol of CH₃OH?

A)3.12 mL
B)9.38 mL
C)167 mL
D)150 mL

Question 36

A solution is 4.50% by weight NaHCO₃.How many grams of NaHCO₃ are in 450.0 g of solution?

A)1.000 g
B)20.2 g
C)400 g
D)450 g

Question 37

A solution is prepared by dissolving 17.75 g sulfuric acid,H₂SO₄,in enough water to make exactly 100.0 mL of solution.If the density of the solution is 1.1094 g/mL,what is the weight % H₂SO₄ in the solution?

A)16.00%
B)18.00%
C)19.00%
D)84.00%

Question 38

What is the molality of a glucose solution prepared by dissolving 9.00 g of glucose,C₆H₁₂O₆,in 125.9 g of water?

A)2.38 × 10^-4 m
B)0.0715 m
C)0.347 m
D)0.397 m

Question 39

A solution is prepared by dissolving 17.75 g sulfuric acid,H₂SO₄,in enough water to make 100.0 mL of solution.If the density of the solution is 1.1094 g/mL,what is the molality?

A)0.1775 m H₂SO₄
B)0.1810 m H₂SO₄
C)1.810 m H₂SO₄
D)1.940 m H₂SO₄

Question 40

A solution is prepared by dissolving 171 g of CdCl₂ in enough water to make exactly 250.0 mL of solution.If the density of the solution is 1.556 g/mL,what is the weight percent of CdCl₂ in the solution?

A)7.17%
B)44.0%
C)56.0%
D)68.4%

Question 41

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.The density of the solution is 1.53 g/mL.Calculate the molarity of this sodium hydroxide solution.

A)0.450 M
B)19.1 M
C)25.0 M
D)125.M

Question 42

Which of the following statements is true for a supersaturated solution?

A)The solute in the solution is at equilibrium with undissolved solute.
B)The solution contains more than the equilibrium amount of solute.
C)The solution is stable and the solute will not precipitate.
D)A supersaturated solution is more than 50% solute by mass.

Question 43

A solution of LiCl in water has X_LiCl = 0.0400.What is the molality?

A)4.16 m LiCl
B)2.22 m LiCl
C)2.31 m LiCl
D)4.21 m LiCl

Question 44

The solubility of argon in water at 25°C is 0.0150 mol/L.What is the Henry's Law constant for argon if the partial pressure of argon in air is 0.00934 atm?

A)1.40 × 10^-4 mol/(L ∙ atm)
B)0.623 mol/(L ∙ atm)
C)1.61 mol/(L ∙ atm)
D)4.10 mol/(L ∙ atm)

Question 45

The solubility of gaseous solutes in liquid solvents is greater when the

A)external pressure over the solution is increased.
B)external pressure is decreased.
C)partial pressure of the gas above the solution is increased.
D)partial pressure of the solvent is increased.

Question 46

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the mole fraction of benzene in the vapor phase over a solution of benzene and toluene with X_benzene = 0.600.

A)0.600
B)0.678
C)0.756
D)0.823

Question 47

Aqueous solutions of 30.0% (by weight)hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Calculate the molality of this solution.

A)0.974 m
B)6.78 m
C)9.79 m
D)12.6 m

Question 48

At 25.0°C,a solution has a concentration of 3.179 M and a density of 1.260 g/mL.The density of the solution at 50.0°C is 1.249 g/mL.What is the molarity of the solution at 50.0°C?

A)2.545 M
B)3.151 M
C)3.179 M
D)3.230 M

Question 49

In general,as the temperature increases,the solubility of gases in water ________ and the solubility of most solids in water ________.

A)decreases,decreases
B)decreases,increases
C)increases,decreases
D)increases,increases

Question 50

Which of the following aqueous salt (NaCl)solutions has the greater concentration?

A)0.5 M
B)2.3 m
C)3.0 % by mass
D)11.1 g/L

Question 51

A 3.17 m solution of CaCl₂ in water has a density of 1.24 g/mL.What is the molarity?

A)2.56 M CaCl₂
B)2.91 M CaCl₂
C)3.50 M CaCl₂
D)3.93 M CaCl₂

Question 52

Aqueous solutions of 30% (by weight)hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Given that the density of the solution is 1.11 g/mL,calculate the molarity.

A)0.794 M
B)6.78 M
C)9.79 M
D)12.6 M

Question 53

A solution is prepared by dissolving 20.0 g of sucrose,C₁₂H₂₂O₁₁,in 250.g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?

A)0.198 mm Hg
B)20.5 mm Hg
C)23.7 mm Hg
D)24.0 mm Hg

Question 54

A solution of LiCl in water is 9.00 wt% LiCl.What is the mole fraction of LiCl?

A)0.0407
B)0.0466
C)0.212
D)2.28

Question 55

Which of the following is not an application of colligative properties?

A)adding silver to mercury to lower the vapor pressure of mercury
B)desalinating sea water by reverse osmosis
C)melting snow by application of salt
D)reduced boiling points of pure liquids at increased altitudes

Question 56

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.Calculate the molality of this sodium hydroxide solution.

A)0.450 m
B)19.1 m
C)25.0 m
D)125.m

Question 57

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the total vapor pressure over a solution of benzene and toluene with X_benzene = 0.400.

A)110 mm Hg
B)133 mm Hg
C)109 mm Hg
D)242 mm Hg

Question 58

A 2.00 M solution of CaCl₂ in water has a density of 1.17 g/mL.What is the mole fraction of CaCl₂?

A)0.0348
B)0.0360
C)0.0366
D)0.0380

Question 59

A KCl solution is prepared by dissolving 60.0 g KCl in 250.0 g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?

A)20.5 mm Hg
B)21.3 mm Hg
C)22.5 mm Hg
D)25.5 mm Hg

Question 60

The Henry's Law constant of methyl bromide,CH₃Br,is k = 0.159 mol/(L ∙ atm)at 25°C.What is the solubility of methyl bromide in water at 25°C and at a partial pressure of 250.mm Hg?

A)0.0523 mol/L
B)0.329 mol/L
C)0.483 mol/L
D)39.8 mol/L

Question 61

Which of the following solutions will have the lowest freezing point?

A)0.0100 m NaCl
B)0.0120 m Li₂SO₄
C)0.0400 m CH₃CH₂CH₂OH
D)0.0150 m MgCl₂

Question 62

How will the osmotic pressure of an aqueous solution change as evaporation occurs?

A)The osmotic pressure will increase.
B)The osmotic pressure will not change.
C)The osmotic pressure will decrease.
D)The osmotic pressure will increase or decrease until it equals the vapor pressure of water.

Question 63

What is the expected freezing point of a 0.50 m solution of Na₂CO₃ in water? K_f for water is 1.86°C/m.

A)-0.93°C
B)-1.9°C
C)-2.8°C
D)-6.5°C

Question 64

The average osmotic pressure of blood is about 7 atm.Therefore

A)the average blood pressure is about 7 atm.
B)the average pressure inside the body is about 7 atm above the external pressure.
C)a pressure of about 7 atm would be required to prevent osmosis if blood is in contact with pure water across a semipermeable membrane.
D)All of these are true.

Question 65

Two aqueous solutions,A and B,are separated by a semipermeable membrane.The osmotic pressure of solution A immediately begins to decrease.Which of the following statements is true?

A)Solvent molecules are moving from solution B into solution A.
B)The initial osmotic pressure of solution B is greater than that of solution A.
C)The solvent molecules are moving from the solution of higher osmotic pressure to that of lower osmotic pressure.
D)Both B and C are true statements.

Question 66

Calculate the freezing point of a solution of 50.0 g methyl salicylate,C₇H₆O₂,dissolved in 800.g of benzene,C₆H₆.K_f for benzene is 5.10°C/m and the freezing point is 5.50°C for benzene.

A)-2.61°C
B)2.61°C
C)2.89°C
D)8.39°C

Question 67

What is the freezing point of a solution of 8.00 g MgCl₂ in 100 g of water? K_f for water is 1.86°C/m for water.

A)1.56°C
B)-1.56°C
C)4.69°C
D)-4.69°C

Question 68

Naproxen is a commercially important anti-inflammatory agent that can be isolated from the thyroid gland.A solution of 1.138 g of naproxen in 25.00 g benzene has an osmotic pressure of 4.00 atm at 20°C.The density of benzene is 0.8787 g/mL at this temperature.Calculate the molar mass of naproxen,assuming it remains intact upon dissolution and the density of the solution equals the density of pure benzene.

A)176 g/mol
B)230 g/mol
C)307 g/mol
D)3.80 × 10⁵ g/mol

Question 69

Red blood cells are placed into pure water.Which of the following statements is true?

A)Water molecules flow out of the red blood cells,causing them to collapse.
B)Water flows into the red blood cells,causing them to swell and burst.
C)The osmotic pressure of the cell contents increases,causing the cells to burst.
D)The osmotic pressure inside the cells equals the osmotic pressure outside.

Question 70

Assuming that sea water is a 3.5 wt % solution of NaCl in water,calculate its osmotic pressure at 20°C.The density of a 3.5% NaCl solution at 20°C is 1.023 g/mL.

A)1.0 atm
B)15 atm
C)29 atm
D)100 atm

Question 71

The normal boiling point of pure benzene is found to be 80.10°C.What is the approximate molecular weight of a nonionizing substance if a solution of 3.55 g of the substance dissolved in 100.g of benzene has a normal boiling point of 80.19°C? K_b = 5.12°C/m for benzene,C₆H₆.

A)20 amu
B)500 amu
C)2000 amu
D)20,000 amu

Question 72

The coolant in automobiles is often a 50/50 % by volume mixture of ethylene glycol,HOCH₂CH₂OH,and water.At 20°C,the density of ethylene glycol is 1.1088 g/mL and the density of water is 0.9982 g/mL.Assuming that the volumes are additive,what is the expected freezing point of a 50/50(v/v)% ethylene glycol/water solution? K_f = 1.86°C/m for water.

A)-16°C
B)-17°C
C)-30°C
D)-33°C

Question 73

A solution of 62.4 g of insulin in enough water to make 1.000 L of solution has an osmotic pressure of 0.305 atm at 25°C.Based on these data,what is the molar mass of insulin?

A)621 g/mol
B)5000 g/mol
C)7570 g/mol
D)71,900 g/mol

Question 74

When 0.500 g of vitamin K is dissolved in 10.0 g of camphor (K_f = 40.0°C/m),the freezing point of the solution is 4.43°C lower than that of pure camphor.Assuming vitamin K is a nonelectrolyte in camphor,calculate its molar mass.

A)0.451 g/mol
B)55.4 g/mol
C)451 g/mol
D)3.54 × 10⁴ g/mol

Question 75

At 25°C the vapor pressures of benzene and toluene are 96.0 mm Hg and 30.5 mm Hg,respectively.When a 1:1 molar mixture of benzene and toluene is fractionally distilled,the first fraction will have a mole fraction of benzene that is closest to

A)0.0.
B)0.5.
C)0.7.
D)1.0.

Question 76

An aqueous solution has a normal boiling point of 105.0°C.What is the freezing point of this solution? For water K_b is 0.51°C/m and K_f = 1.86°C/m.

A)14.7°C
B)-14.7°C
C)18.2°C
D)-18.2°C

Question 77

How many grams of sucrose,C₁₂H₂₂O₁₁,must be added to 500.g of water at 100°C to change the vapor pressure to 752 mm Hg?

A)0.295 g
B)5.32 g
C)10.6 g
D)101 g

Question 78

When ethylene glycol,HOCH₂CH₂OH,is added to the water in an automobile radiator,the effect is to

A)lower the boiling point and lower the freezing point.
B)lower the boiling point and raise the freezing point.
C)raise the boiling point and lower the freezing point.
D)raise the boiling point and raise the freezing point.

Question 79

An aqueous CsCl solution is 8.00 wt% CsCl and has a density of 1.0643 g/mL at 20°C.What is the boiling point of this solution? K_b = 0.51°C/m for water.

A)100.27°C
B)100.53°C
C)103.8°C
D)104.3°C

Question 80

A solution of 0.2113 g of water dissolved in 25.0 g of a solvent freezes at 11.5°C below the freezing point of the solvent.What is K_f for this solvent?

A)0.735°C/m
B)1.36°C/m
C)5.39°C/m
D)24.5°C/m