Chapter 13 - Properties of Solutions

Question 1

Define solutions.

Answer 1

homogeneous mixtures of two or more pure substances

Question 2

Define solute.

Answer 2

the minor component in a solution; dissolved in the solvent

Question 3

Define solvent.

Answer 3

a substance that dissolves a solute, resulting in a solution

Question 4

What does the ability of substances to form solutions depend on?

Answer 4

natural tendency toward mixing, intermolecular forces

Question 5

How is the mixing of gases a spontaneous process?

Answer 5

each gas acts as if it is alone to fill the container

Question 6

How does mixing increase entropy?

Answer 6

it causes more randomness in the position of molecules

Question 7

How is the formation of solutions affected by mixing?

Answer 7

it is favored by the increase in entropy which accompanies it

Question 8

Which intermolecular force of attraction exists between solute and solvent?

Answer 8

any of the intermolecular forces of attraction can exist between solute and solvent molecules

Question 9

What must happen to solute-solute interactions when making a solution?

Answer 9

solute-solute interactions must be overcome

Question 10

What must happen to solvent-solvent interactions when making a solution?

Answer 10

solvent-solvent interactions must be overcome

Question 11

When do solvent-solute interactions occur?

Answer 11

solvent-solute interactions occur as the particles in a solution mix

Question 12

What must be true for a reaction to occur?

Answer 12

ΔHmix must be close to the sum of ΔHsolute and ΔHsolvent

Question 13

If a substance disappears when it comes in contact with a solvent, has it definitely dissolved?

Answer 13

no, it may have reacted

Question 14

What is the opposing process to solution-making?

Answer 14

crystalization

Question 15

What is true of a saturated solution?

Answer 15

When the rate of the opposing processes is equal, additional solute will not dissolve unless some crystallizes from solution.

Question 16

What is true of an unsaturated solution?

Answer 16

If we have not yet reached the amount that will result in crystallization, we have an unsaturated solution.

Question 17

Define solubility.

Answer 17

the maximum amount of solute that can dissolve in a given amount of solvent at a given temperature

Question 18

What is true of a supersaturated solution?

Answer 18

In supersaturated solutions, the solvent holds more solute than is normally possible at that temperature.

Question 19

How can crystallization be stimulated in a supersaturated solution?

Answer 19

by adding a “seed crystal” or scratching the side of the flask

Question 20

Supersaturated solutions are (common/uncommon) solutions.

Answer 20

uncommon

Question 21

List three factors that affect solubility.

Answer 21

• solute-solvent interactions
• pressure (for gaseous solutes)
• temperature

Question 22

The (stronger/weaker) the solute-solvent interaction, the (greater/less) the solubility of a solute in a solvent.

Answer 22

stronger, greater

Question 23

The (larger/smaller) the gas, the (more/less) soluble it will be in water.

Answer 23

larger, more

Question 24

Polar organic molecules dissolve in water (better/worse) then nonpolar organic molecules.

Answer 24

better

Question 25

Hydrogen bonding (increases/decreases) solubility, since C-C and C-C (are/are not) very polar.

Answer 25

increases, are

Question 26

Define miscible.

Answer 26

liquids that mix in all proportions

Question 27

Define immiscible.

Answer 27

liquids that do not mix in one another

Question 28

Because hexane is nonpolar and water is polar, they are (miscible/immiscible).

Answer 28

immiscible

Question 29

What is the biological significance of solubility?

Answer 29

Fat soluble vitamins are nonpolar and are readily stored in fatty tissue of the body; water soluble vitamins need to be included in the daily diet.

Question 30

The solubility of solids and liquids (are/are not) appreciably affected by pressure.

Answer 30

are not

Question 31

Gas solubility (is/is not) affected by pressure.

Answer 31

is

Question 32

What relationship does Henry's Law describe?

Answer 32

the solubility of a gas is proportional to the partial pressure of the gas above the solution

Question 33

For (all/most/no) solids, as temperature increases, solubility increases.

Answer 33

most

Question 34

For (all/most/no) gases, as temperature increases, solubility decreases.

Answer 34

all

Question 35

List six units of concentration used for solutions.

Answer 35

- Mass percentage - Parts per million (ppm) - Parts per billion (ppb) - Mole fraction - Molarity - Molality

Question 36

How is mass percentage calculated?

Answer 36

the ratio of the mass of the solute to the total solution mass, multiplied by 100

Question 37

How is parts per million calculated?

Answer 37

the ratio of the mass of the solute to the total solution mass, multiplied by 10^6

Question 38

How is parts per billion calculated?

Answer 38

the ratio of the mass of the solute to the total solution mass, multiplied by 10^9

Question 39

How is mole fraction calculated?

Answer 39

the ratio of moles of a substance to the total number of moles in a solution

Question 40

How is molarity calculated?

Answer 40

the ratio of moles of solute to the total liters of solution

Question 41

How is molality calculated?

Answer 41

the ratio of moles of solute to the total kilograms of solvent

Question 42

Molality (does/does not) vary with temperature.

Answer 42

does not

Question 43

Molarity (does/does not) vary with temperature.

Answer 43

does

Question 44

What must be used to convert between molality and molarity?

Answer 44

the density of the solution

Question 45

What do colligative properties depend on?

Answer 45

the quantity of the solute particles

Question 46

List four colligative properties.

Answer 46

- Vapor-pressure lowering - Boiling-point elevation - Freezing-point depression - Osmotic pressure

Question 47

The vapor pressure of a solution is (higher/lower) then that of the pure solvent.

Answer 47

lower

Question 48

What relationship does Raoult's Law describe?

Answer 48

The vapor pressure of a volatile solvent over the solution is the product of the mole fraction of the solvent times the vapor pressure of the pure solvent.

Question 49

In ideal solutions, it (is/is not) assumed that each substance will follow Raoult's Law.

Answer 49

is

Question 50

Why is boiling point raised in solutions?

Answer 50

vapor pressures are lowered

Question 51

What happens to the freezing point of a solution as the boiling point is raised?

Answer 51

the freezing point is lowered

Question 52

What is the relationship between boiling point elevations/freezing point depression and molality?

Answer 52

The change in temperature is directly proportional to molality.

Question 53

What does the van't Hoff Factor describe?

Answer 53

it takes into account dissociation in solution

Question 54

Define semipermeable membrane.

Answer 54

a membrane that allows some smaller particles to pass through but blocks larger particles

Question 55

Define osmosis.

Answer 55

the net movement of solvent molecules from solution of low to high concentration across a semipermeable membrane

Question 56

Define osmotic pressure.

Answer 56

the applied pressure to stop osmosis

Question 57

If two solutions seperated by a semipermeable membrane have (the same/different) osmotic pressure, no osmosis will occure.

Answer 57

the same

Question 58

Define colloid suspension.

Answer 58

a suspension of particles larger then individual ions or molecules but too small to be settled out by gravity

Question 59

Define Tyndall effect.

Answer 59

the ability of colloid suspensions to scatter rays of light

Question 60

What does an emulsifier do?

Answer 60

it causes something that does not normally dissolve in a solvent to do so

Question 61

Define Brownian Motion.

Answer 61

motion of colloids due to numerous collisions with the much smaller solvent