Deck 9: Properties of Solutions

Question 1

Work with and interconvert concentration units (mass %, molarity, molality, mole fraction, ppm, and ppb).

Answer 1

The solvent determines the phase of the solution. Concentrations are expressed as amount of solute divided by the amount of solvent, or by the amount of solution.

Question 2

Predict the relative solubilities of a solute in various solvents, and explain in terms of intermolecular forces.

Answer 2

Substances that dissolve in each other usually have similar types of intermolecular interactions ("like dissolves like").

Question 3

Calculate and explain solubilities in water.

Answer 3

Enthalpies of solution and of dilution depend on the lattice energy of the salt as well as the hydration energies of its ions. The solubility of a gas in a liquid depends on the partial pressure of the gas.

Question 4

Understand the reasons for and calculate the magnitudes of colligative properties.

Question 5

Understand some aspects of colloidal suspensions and surfactant solutions.

Question 6

What is the molarity of a solution made from mixing 34 grams of CaCl₂ with enough water to make 150 ml of solution?

A) 2.04 M
B) 1.02 M
C) 3.60 M
D) 0.20 M
E) 0.34 M

Question 7

What is the molarity of an aqueous solution that is 0.569 m CaCl₂ (solution density 1.05 g/ml)?

A) 0.569 M
B) 0.562 M
C) 0.597 M
D) 0.507 M
E) 0.507 m

Question 8

What is the mass percent of an aqueous solution that is 0.569 m CaCl₂ (solution density 1.05 g/ml)?

A) 5.94 %
B) 6.32 %
C) 0.06 %
D) 5.94 x 10^-2 %
E) 6.32 x10^-2%

Question 9

What is the mole fraction of CaCl₂ in an aqueous solution that is 0.569 m CaCl₂ (solution density 1.05 g/ml)?

A) 0.01 M
B) 0.01
C) 0.57
D) 0.10
E) 9.6 x 10^-3

Question 10

What is the molality of a radiator solution made by mixing equal volumes of ethylene glycol C₂H₆O₂, (density = 1.11 g/ml) and water?

A) 17.9 m
B) 11.1 m
C) 1.79 m
D) 4.60 m
E) 17.9 M

Question 11

What is the molality of a solution made from mixing 39 grams of sugar (MM = 180 g/mol) with 310 grams of water?

A) 0.70 m
B) 1.40 m
C) 0.39 m
D) 3.10 m
E) 0.39 M

Question 12

What is the mole fraction of ethyl alcohol (C₂H₆O, density = 0.79 g/ml) in water for a solution made from equal volumes of each?

A) 0.235
B) 0.122
C) 0.756
D) 1.11
E) 17.9

Question 13

Why was the concentration unit of molality developed?

A) Molarity had not been developed yet.
B) Morality had not been developed yet.
C) Solution volumes changed with temperature.
D) Solution volumes changed with pressure.
E) Solution masses changed upon mixing.

Question 14

The interactions that play an important role in the dissolution of a salt in water are
I. ion-dipole
II. hydrogen bonding
III. dipole-dipole
IV. ion-ion

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

Question 15

Benzene and water are immiscible, forming two separate layers when mixed. Samples of the compounds below are shaken in a mixture of benzene and water. Which of the following compounds would you expect to be found in the benzene layer?

A) 2 and 4
B) 2 and 3
C) 1 and 4
D) 1 and 3
E) 1, 3 and 4

Question 16

List the following in order of solubility in hexane:
1) CH₃CH₂C(O)CH₃,
2) C₆H₆,
3) CH₃CH₂CH₂CO₂H,
4) CH₃CH₂CH₂CH₂CO₂H

A) 2 < 1 < 3 < 4
B) 1 < 3 < 4 < 2
C) 3 < 4 < 1 < 2
D) 4 < 3 < 1 < 2
E) 1 < 2 < 3 < 4

Question 17

How can mercury be used in dental fillings?

A) It is a solid at body temperature.
B) It forms an amalgam with your tooth enamel.
C) It forms an amalgam with other metals.
D) It is an insoluble salt in your mouth.
E) It forms a compound called brass with copper.

Question 18

Which of the following statements regarding alloys is(are) true?
I. Alloys are homogeneous solid solutions
II. Alloys display metallic properties
III. The solute component in the alloy can replace the solvent component in the solid crystalline structure
IV. The solute component can be incorporated in between solvent atoms in the crystal structure

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

Question 19

What is the concentration of chloride ions in a solution that is 0.569 m CaCl₂ (solution density 1.05 g/ml)?

A) 0.569 M
B) 0.562M
C) 1.124 M
D) 0.507 M
E) 1.138 M

Question 20

What is the concentration of all ions in a solution that is 0.569 m CaCl₂ (solution density 1.05 g/ml)?

A) 0.569 M
B) 0.562M
C) 1.124 M
D) 1.686 M
E) 2.248 M

Question 21

The greatest gas solubility for a gas in solution is predicted under what conditions?

A) low T, low P
B) low T, high P
C) high T, low P
D) high T, high P
E) Solubility of gases does not depend upon temperature.

Question 22

Consider a warm (30°) 355 mL can of soda, under 2.5 atm CO₂ pressure. What volume of CO₂ will be released from the soda in order to reach equilibrium after opening to the room where the pressure of CO₂ = 3.25 x 10^-4 atm and the total pressure is 758 mm Hg (K_H = 1.6 x 10^-2 M/atm)?

A) 3.5 mL
B) 3.5 L
C) 35 mL
D) 0.35 L
E) 100 mL

Question 23

According to Henry's Law, the solubility of a gas in a liquid

A) depends on the polarity of the liquid.
B) depends on the liquid's density.
C) remains the same at all temperatures.
D) increases as the gas pressure above the solution increases.
E) decreases as the gas pressure above the solution increases.

Question 24

Carbon dioxide and O₂ are non-polar molecules. Can you provide some rational why CO₂ dissolves so much more in water than O₂?

A) CO₂ can hydrogen bond and O₂ cannot.
B) CO₂ reacts with water and O₂ does not.
C) O₂ reacts with water and CO₂ does not.
D) CO₂ forms a solid with water.
E) Water decomposes to O₂.

Question 25

Which of the following has the substances arranged in order of increasing heat of fusion?

Question 26

Which of the following statements regarding solubility as a function of temperature are correct?
I. Gas solubility favours high temperature and high pressure.
II. Gas solubility favours low temperature and high pressure.
III. Since the dissolution of solids into liquids is exothermic, solid solubility favours high temperature.
IV. Endothermic dissolution of solids in liquids is favoured by lower temperature.
V. Endothermic dissolution of solids in liquids is favoured by higher temperature.

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

Question 27

The vapour pressure of toluene at 25^oC is 3.79 KPa and that of benzene is 12.7 kPa. The vapour above a solution that has mole fraction of benzene = 0.5,

A) has mole fraction toluene in 0.5.
B) has mole fraction of toluene less than 0.5.
C) has mole fraction of toluene greater than 0.5.
D) is pure benzene.
E) is pure toluene.

Question 28

The boiling point of toluene is 110^oC and that of benzene is 80^oC. The vapour above a solution that has mole fraction of benzene = 0.5,

A) has mole fraction toluene in 0.5.
B) has mole fraction of toluene less than 0.5.
C) has mole fraction of toluene greater than 0.5.
D) is pure benzene.
E) is pure toluene.

Question 29

Sea water has about 0.46 moles NaCl and 0.065 moles of MgCl₂ in every litre. What is the vapour pressure of sea water at 30?C if pure water would have a vapour pressure of 33.2 mm Hg? (Assume there are 1000 grams of water in 1 litre of sea water.)

A) 33.2 mm Hg
B) 32.5 mm Hg
C) 37.0 mm Hg
D) 30.3 mm Hg
E) 32.9 mm Hg

Question 30

Which aqueous solution would be expected to have the highest boiling point?

A) 0.10 M NaCl
B) 0.080 M CaCl₂
C) 0.064 M Fe(NO₃)₃
D) 0.081 M Fe(NO₃)₂
E) 0.080 M Co(SO₄)

Question 31

In the textbook it was discussed how the melting point is decreased and the boiling point is elevated for a solvent with a solute in it. What happens to the triple point of that solvent? Does the triple point

A) remain at the same pressure and temperature?
B) stay at the same pressure, but warmer temperature?
C) stay at the same pressure, but cooler temperature?
D) occur at a lower pressure and temperature?
E) occur at a higher pressure and temperature?

Question 32

Solutions used for intravenous injections must be isotonic, that is, exert an osmotic pressure of 6.9 atm. An isotonic saline solution uses sodium chloride as the solute to achieve isotonic conditions. Use this value for the osmotic pressure to estimate the % NaCl by mass in an isotonic saline solution at 37°C (assume the solution has a density of 1.0 g/mL).

A) 0.40%
B) 0.50%
C) 0.60%
D) 0.80%
E) 0.90%

Question 33

A major component of cell membranes is the phospholipid bilayer. Which of the following statements is(are) FALSE?
I. The bilayer provides a barrier to charged ions
II. Polar molecules such as glucose can pass through the membrane
III. Protein molecules act as gates in the phospholipid bilayer allowing nutrients to enter into the cell
IV. The bilayer consists of two nearly parallel rows with the hydrophobic tails facing out toward the solution and acting as a barrier to water soluble species.

A) all
B) II and I
C) I and III
D) II and IV
E) III and IV

Question 34

Which of the following molecules would be suitable surfactants?
1)
2)
3)
4)

A) all
B) 1 and 2
C) 1 and 3
D) 2 and 4
E) 1 and 4

Question 35

Which of the following are true solutions: milk, brass, NaCl in water, sugar in water, ink?

A) milk, NaCl in water, sugar in water
B) milk, brass, NaCl in water, sugar in water
C) NaCl in water, sugar in water, ink
D) brass, NaCl in water, sugar in water
E) NaCl in water, sugar in water

Question 36

Which of the following are colloidal suspensions: fog, milk, sugar in water, salt in water, styrofoam?

A) fog and milk
B) milk, sugar in water, styrofoam
C) fog, sugar in water styrofoam
D) fog, milk, styrofoam
E) fog and styrofoam

Question 37

A mixture that does NOT settle out upon standing is

A) solid.
B) a suspension.
C) tyndall solution.
D) a colloid.
E) hydrated.

Question 38

Classify the following molecules or fragments as hydrophobic or hydrophilic. A line from an atom indicates where a bond would be formed to another fragment.
1. the -CH₂SO₃^- group
2. CH₃CH₂OH
3 the -CH₂(CH₂)₁₁CH₃ group
4. the -NH₃⁺ group

A) 1; hydrophilic: 2; hydrophilic: 3; hydrophilic: 4; hydrophobic
B) 1; hydrophilic: 2; hydrophobic: 3; hydrophilic: 4; hydrophobic
C) 1; hydrophilic: 2; hydrophilic: 3; hydrophobic: 4; hydrophilic
D) 1; hydrophilic: 2; hydrophobic: 3; hydrophilic: 4; hydrophilic
E) 1; hydrophobic: 2; hydrophilic: 3; hydrophilic: 4; hydrophilic

Question 39

Which part of soap is responsible for its ability to mix with oily dirt?

A) the carboxylate end
B) the salt end
C) the hydrophilic end
D) the hydrophobic end
E) the ionized "head"

Question 40

Pesticides are non-polar molecules in general. What needs to be done so that farmers are able to spray aqueous solutions containing pesticides?

A) The solutions need to be heated.
B) An emulsifier is added.
C) A miscible agent is added.
D) The solution is shaken frequently.
E) Pesticides will never make a solution with water.

Question 41

A solution is made from dissolving 102 grams of potassium carbonate in 100 grams of water. What is the solvent in this solute in the solution and explain.

Question 42

Determine the mole fraction of a solution made from mixing 39 grams of sugar (MM = 180 g/mol) with 310 grams of water.

Question 43

Industrial grade concentrated HCl is known as muriatic acid and is 31.45% by mass HCl in water. What is the molality of this solution?

Question 44

The molecule drawn below is Vitamin D, Calciferol. Would you predict this molecule to be more soluble in water or body fat and explain why?

Question 45

The molecule drawn below is Vitamin B1, thiamine. Would you predict this molecule to be more soluble in water or body fat and explain why?

Question 46

Pesticides have been found to accumulate and affect the growth of animals higher in food chain. Can you give some rational for this, including discussion of the solubility of pesticides in general?

Question 47

When both solid Na metal and solid NaCl are added to water a colourless solution develops. How are these processes different?

Question 48

Consider a can containing 355 mL of a carbonated soft drink at 0°C under 2.2 atm CO₂ pressure. What is the concentration of CO₂ in the soda, assuming that K_H = 7.8 x 10^-2 M/atm?

Question 49

The problem with hot water heaters in some parts of the country is that a solid forms inside of them, CaCO₃. Predict if the solvation process for CaCO₃ is endothermic or exothermic and if it is more soluble or less soluble at colder temperatures.

Question 50

Fahrenheit developed his temperature scale where he set zero degrees as the freezing point for a salt-water solution. What is the concentration of this salt solution in molality (assume NaCl in water)? (T_f = 1.86 ˚C/m)

Question 51

Automobile coolant is about 50% by mass ethylene glycol in water. The line structure of ethylene glycol is shown below: What is the normal boiling point of this solution if K_b for water = 0.512 ˚Cm^-1?

Question 52

If you have ever made homemade ice cream you would know that you need to add salt to the ice surrounding the container that you make the ice cream in. By adding the salt to the ice it lowers the temperature of the ice. Explain what is happening to the salt when added to the ice and what you can say about the heat of solvation for sodium chloride.

Question 53

When 0.64 g of adrenaline is dissolved in 36.0 g benzene (K_f = 5.12 °C), the freezing point is lowered by 0.50°C. Determine the molecular mass of adrenaline.

Question 54

A 7.85 g sample of a compound with an empirical formula C₁H₁ is dissolved in 172 g of benzene. The freezing point of the solution is 1.50 $\degree$ C below that of pure benzene. Assuming that the compound does not dissociate, what is the molar mass and molecular formula of this compound? The freezing point depression constant for benzene is K_f = 5.12 $\degree$ C/m.

Question 55

To what minimum temperature would a radiator be protected if equal volumes of ethylene glycol (permanent antifreeze) (density 1.11 g/mL) and water were mixed? Assume that ethylene glycol does not dissociate and has a formula, C₂H₆O₂. (K_f = 1.85 ˚Cm^-1).

Question 56

What is the freezing point of a solution made from mixing 39 grams of sugar (MM = 180 g/mol) with 310 grams of water? (K_f = 1.85 ˚Cm^-1)?

Question 57

Lysozyme is an enzyme found in tears whose function is to break down bacterial cell walls thus killing the bacteria and protecting the eye from infection. A solution made which contains 0.100 g of lysozyme in 150 g of water ( $\rho$ = 1.00 g/mL) at 25°C has an osmotic pressure of 8.9 Torr. What is the molar mass of this enzyme?

Question 58

Draw a molecular picture of a surfactant on a waxed surface, like soapy water on a freshly waxed car.

Question 59

Ben Franklin determined Avogadro's number within a factor of 5. He was able to do this by dropping 1 teaspoon of oil on a still pond and determined the area covered by the oil at about ¾ of an acre. You can simulate this by adding 1 drop of soap on the top of a greasy pan in the kitchen and watch the grease move to the sides. Sketch the interaction of the soap with the layer of water and sketch how the soap "dissolves" grease in water.