Chapter 11 Solutions & Colloids Flashcards
(156 cards)
1
Q
What is solubility?
A
Maximum amount of solute dissolved in solvent at a specific temperature.
Units: g solute / 100 g solvent or g solute / 100 mL solvent.
2
Q
What is an unsaturated solution?
A
Contains less than the maximum amount of solute that a solvent can hold at a specific temperature; not in equilibrium with dissolved substance.
3
Q
What is a saturated solution?
A
Contains the maximum amount of solute that a solvent can hold at a specific temperature; rate at which the solute leaves the solid state equals the rate at which the solute returns to the solid state.
4
Q
What is a supersaturated solution?
A
Contains more than the maximum amount of solute that a solvent can hold at a specific temperature.
5
Q
What is a solution?
A
A homogeneous mixture of a solute dissolved in a solvent.
6
Q
What is a solute?
A
The component present in a smaller amount in a solution.
7
Q
What is a solvent?
A
The component present in a greater amount in a solution.
8
Q
What is an aqueous solution?
A
A solution that contains water as the solvent and a solid, liquid, or gas as the solute.
9
Q
What is an example of an aqueous solution?
A
Seawater, where salt is the solute and water is the solvent.
10
Q
How does temperature affect solubility?
A
Higher temperature allows solvents to hold more solute than at lower temperatures.
11
Q
What happens when a solution is cooled undisturbed?
A
The solute remains in solution, but the solution is unstable.
12
Q
What occurs if a cooled solution is disturbed?
A
The solute will ‘fall out’ of the solution.
13
Q
What is the difference between hot packs and cold packs?
A
Hot packs recrystallize in an exothermic reaction, while cold packs recrystallize in an endothermic reaction.
14
Q
What happens when polar and nonpolar molecules are mixed?
A
Polar molecules will not mix (be immiscible) with nonpolar molecules.
15
Q
What is the result of mixing nonpolar molecules?
A
Nonpolar molecules will mix (be miscible) with other nonpolar molecules.
16
Q
What is the result of mixing polar molecules?
A
Polar molecules will mix (be miscible) with other polar molecules.
17
Q
What is the principle that explains the mixing behavior of similar types of molecules?
A
“Like dissolves Like”.
18
Q
What forms when less dense oil substances are mixed with water?
A
Layers will form with the less dense oil floating on top of the water.
19
Q
What are the two types of mixtures discussed?
A
Immiscible and miscible mixtures.
20
Q
What does ‘Like dissolves Like’ mean?
A
‘Like dissolves Like’ means that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.
21
Q
What is a solid solute?
A
A solid solute can be polar, nonpolar, or ionic.
22
Q
What are insoluble solids?
A
Insoluble solids do not dissolve in solvents.
23
Q
What are solubility rules?
A
Solubility rules help determine whether a substance is soluble or insoluble in a solvent.
24
Q
What is hydration energy?
A
Hydration energy is the energy released when ions are surrounded by water molecules.
25
What is the ion-dipole force?
Ion-dipole force is the energy of attraction between ions and water.
26
What is hydration?
Hydration is the attraction of ions for water molecules.
27
How does ion size affect hydration energy?
Smaller ions have larger hydration energy, making them more soluble.
28
What is the relationship between charge concentration and attraction to water?
A more concentrated charge results in a stronger attraction to water.
29
Do metals dissolve in solvents?
Metals react with solvents but do not dissolve.
30
What are network covalent solids?
Network covalent solids, such as graphite and quartz, never dissolve in any solvent.
31
What is the force of attraction between ions and water?
It is the interaction that facilitates the dissolving of ionic solutes in water.
32
Where does dissolving occur in the process of ionic solutes in water?
Dissolving occurs at the surfaces of the solid.
33
What causes differences in solubility of ionic solutes in water?
Differences in solubility are due to the different energies of attraction between ions in crystal and ions in water.
34
What characterizes a soluble substance?
A soluble substance has large hydration energy (H.E.) and small lattice energy (L.E.).
35
What is lattice energy?
Lattice energy is the energy holding ions together, which opposes dissolving.
36
How does charge affect lattice energy?
Greater charge (+2, +3) results in greater lattice energy due to stronger attraction between ions (Coulomb's Law).
37
How does lattice energy change down a group?
Lattice energy decreases down a group.
38
What happens to lattice energy as ion size increases?
As size increases, ions cannot get as close to one another, leading to lower lattice energy.
39
What is the relationship between lattice energy and solubility?
Large lattice energy typically indicates an insoluble ionic solid.
40
What happens to gas solubility as temperature increases?
As temperature increases, the solubility of a gas decreases in most cases.
## Footnote
Example: A glass of soda quickly goes flat on a hot day.
41
Why do bubbles form when water is heated in an open pan?
Bubbles form because gas molecules move more quickly at higher temperatures, leading to a higher tendency to escape the liquid.
42
What is the effect of higher temperature on gas molecules in a liquid?
At higher temperatures, gas molecules have a higher tendency to find the surface and escape more quickly, resulting in fewer gas molecules remaining in the liquid.
43
What generally affects solubility?
Solubility generally depends on temperature.
44
How does temperature usually affect solubility?
In most cases, solubility increases with increasing temperature.
45
What is an exception to the general trend of solubility with temperature?
For a number of compounds, solubility decreases with increasing temperature.
46
What explains the difference in solubility behavior with temperature?
The difference is explained by differences in the heat of solution.
47
What happens when dissolving absorbs heat?
When dissolving absorbs heat (is endothermic), the temperature of the solution decreases as the solute dissolves. The solubility will increase as temperature increases.
48
What happens when dissolving releases heat?
When dissolving releases heat (is exothermic), the temperature of the solution increases as the solute dissolves. The solubility will decrease as temperature increases.
49
How does pressure affect the solubility of solids or liquids in water?
In general, pressure has little or no effect on the solubility of solids or liquids in water.
50
What happens to the solubility of a gas as pressure increases?
The solubility of a gas increases as pressure increases.
51
What is the effect of pressure on the solubility of solids or liquids in water?
In general, pressure has little or no effect on the solubility of solids or liquids in water.
52
What does P represent in Henry's Law?
P = partial pressure of gas over solution.
53
What does ky represent in Henry's Law?
ky = Henry's law constant for the gas.
54
What does C represent in the context of gas solubility?
C = gas solubility.
55
What is the relationship between gas solubility and partial pressure?
The solubility of a gas is proportional to the partial pressure of the gas above the liquid.
56
What is a dilute solution?
A dilute solution contains small amounts of solute relative to the amount of solvent.
57
What is a concentrated solution?
A concentrated solution contains large amounts of solute relative to the amount of solvent.
58
What is the mass of glucose in the practice example?
5.67 g glucose
59
What does percent by mass (%) refer to?
mass solute x 100 / total amount solute in solvent (in mol)
60
What is the formula for mole fraction?
amount solute (in mol) / total amount solute in solvent
61
What is molality (m)?
amount solute (in mol) / mass solvent (in kg)
62
What is the formula for molarity (M)?
amount solute (in mol) / volume solution (in L)
63
What are the units for mass?
kg
64
What are the units for amount of substance?
mol
65
What are the units for volume?
L
66
What is mole fraction used for?
Mole fraction is used for partial pressure of gases and vapor pressure of solutions.
67
Why is molarity preferred over molality?
Molarity is preferred because it is easier to measure the volume of solution than to weigh the solvent.
68
What is a key characteristic of molality?
Molality is independent of temperature, making it useful when experiments are carried out over a range of temperatures.
69
What is a characteristic of mass percent?
Mass percent is independent of temperature; molarity is not needed.
70
What are colligative properties?
Properties depending on the number of solute particles in solution, not the nature of the solute particles.
71
What is vapor pressure lowering?
A colligative property that describes the decrease in vapor pressure of a solvent when a solute is added.
72
What is boiling point elevation?
A colligative property that describes the increase in boiling point of a solvent when a solute is added.
73
What is freezing point depression?
A colligative property that describes the decrease in freezing point of a solvent when a solute is added.
74
What is osmotic pressure?
A colligative property that describes the pressure required to prevent the flow of solvent into a solution through a semipermeable membrane.
75
What is vapor pressure lowering?
When the solute is nonvolatile, the vapor pressure of a solution is the mole fraction of the solvent times the vapor pressure of pure solvent.
76
What is Raoult's Law?
P_solution = X_solvent * P°_solvent
## Footnote
P_solution = vapor pressure of the solvent in solution, X_solvent = mole fraction of the solvent, P°_solvent = vapor pressure of the pure solvent.
77
What are electrolytes?
Electrolytes exist as ions in solution (dissociate).
78
What are nonelectrolytes?
Nonelectrolytes exist as molecules in solution (do not dissociate).
79
What happens to vapor pressures and concentrations at equilibrium?
They become equal.
80
What occurs to the gaseous solvent in a concentrated solution?
It will condense.
81
What happens to the surface of a solution when solute is present?
The surface is occupied by solvent molecules.
82
What occurs at the surface of the solution?
Evaporation occurs.
83
How does the presence of solute affect the vapor pressure of a solution?
The vapor pressure of a solution, P, is less than the vapor pressure of the pure solvent, Po.
84
What effect does adding a solute have on the concentration of solvent molecules?
It lowers the concentration of solvent molecules.
85
What is the term for the phenomenon where the vapor pressure decreases upon adding a solute?
Vapor Pressure Lowering.
86
What is Freezing Point Depression?
The freezing point of a solution is lower than the freezing point of the pure solvent.
87
What determines the change in freezing point?
The amount of impurity (solute present) determines how much the freezing point changes.
88
How is freezing point depression used in winter?
Salt is added to roads and sidewalks to prevent freezing in winter.
89
What is the equation for freezing point depression?
T_f = T_f° - ΔT_f
90
What do the variables T_f and T_f° represent?
T_f is the freezing point of the solution, and T_f° is the freezing point of the pure solvent.
91
What is ΔT_f?
ΔT_f is the freezing point depression.
92
How is freezing point depression (ΔT_f) calculated?
ΔT_f = K_f * m
93
What do the variables K_f and m represent?
K_f is the molal freezing point constant, and m is the molal concentration of the solute.
94
What is boiling point elevation?
Boiling point elevation is when the boiling point of a solution is higher than the boiling point of the pure solvent.
95
How does the presence of solute affect vapor pressure?
The presence of solute lowers the vapor pressure of the solution.
96
What effect do solute particles have at the interface?
Solute particles present at the interface block solvent molecules from escaping.
97
How can you increase the boiling point of water?
You can add salt to water to increase the boiling point of water.
98
What is the formula for boiling point elevation?
The formula for boiling point elevation is T_b = T_0 + ΔT_b.
99
What does T_b represent in the boiling point elevation formula?
T_b represents the boiling point of the solution.
100
What does T_0 represent in the boiling point elevation formula?
T_0 represents the boiling point of the pure solvent.
101
What does ΔT_b represent in the boiling point elevation formula?
ΔT_b represents the boiling point elevation.
102
What is the equation for boiling-point elevation?
The boiling-point elevation, ΔT_b, is given by the equation: ΔT_b = K_b * m.
103
What does K_b represent in the boiling-point elevation equation?
K_b is the molal boiling point constant.
104
What does m represent in the boiling-point elevation equation?
m represents the molal concentration of solute.
105
What is a semipermeable membrane?
A semipermeable membrane allows solvent molecules to pass through but blocks the passage of solute molecules.
106
What is osmosis?
Osmosis is the net movement of solvent molecules through a semipermeable membrane from a pure solvent or a more dilute solution to a more concentrated solution.
107
What causes osmosis?
Osmosis is the result of differences in vapor pressure due to differences in concentrations.
108
What is osmotic pressure?
Osmotic pressure is the pressure required to stop osmosis.
109
What does isotonic mean?
Isotonic refers to when two solutions have equal osmotic pressure.
110
What is a hypertonic solution?
A hypertonic solution is the more concentrated solution, given two solutions with different osmotic pressures.
111
What is a hypotonic solution?
A hypotonic solution is the less concentrated solution, given two solutions with different osmotic pressures.
112
What is reverse osmosis?
Reverse osmosis is the process of making water molecules go from a solution to pure water by applying a large amount of external pressure.
113
What is the formula for osmotic pressure?
II = n = MRT
114
What does 'II' represent in the osmotic pressure formula?
II = Osmotic Pressure
115
What does 'M' represent in the osmotic pressure formula?
M = solute molarity
116
What is the value of R in the osmotic pressure formula?
R = 0.08206 L atm/molK
117
What does 'T' represent in the osmotic pressure formula?
T = temperature in K
118
What is the osmotic pressure of a 0.30 M glucose solution at 37 °C?
Osmotic Pressure = (0.30 m) (0.08206 L atm/molK) (310 K)
## Footnote
This calculation assumes ideal solution behavior.
119
What can colligative properties be used to determine?
The molar mass of an unknown solute.
120
Which colligative properties are most commonly used for molar mass determination?
Freezing point lowering (ΔT_f) and osmotic pressure (π).
121
What is the first step in the typical procedure for determining molar mass?
Add a known mass of the solute to either a known mass of the solvent or to create a solution of known volume.
122
What should be measured after adding the solute?
Measure the colligative property (ΔT_f or π).
123
What is calculated after measuring the colligative property?
Calculate the concentration (m or M) of the solute.
124
What is determined from the concentration of the solute?
The number of moles of solute present.
125
What is the final calculation in the procedure?
Calculate the molar mass (MM).
126
What is the formula for molar mass?
MM = g/mole.
127
What is a colloid?
A colloid is a dispersion of particles of one substance (the dispersed phase) throughout another substance or solution (the continuous phase).
128
What is the size range of dispersed particles in a colloid?
Dispersed particles range from 1000 pm to 200,000 pm in size, much larger than single molecules or single ions.
129
Give an example of a colloid.
Fog is an example of a colloid, where water droplets are dispersed through air.
130
How are colloids characterized?
Colloids are characterized according to the state (solid, liquid, or gas) of the dispersed phase and the state of the continuous phase.
131
What are aerosols?
Aerosols are colloids where liquid droplets or solid particles are dispersed throughout a gas.
132
What is an emulsion?
An emulsion consists of liquid droplets dispersed throughout another liquid.
133
Give an example of an emulsion.
An example of an emulsion is butterfat dispersed through homogenized milk.
134
What is a sol?
A sol consists of solid particles dispersed in a liquid.
135
What are the two major classes of colloids with water as the continuous phase?
Hydrophilic colloids and hydrophobic colloids.
136
What characterizes a hydrophilic colloid?
Strong attraction between the dispersed phase and the continuous phase (water).
137
What characterizes a hydrophobic colloid?
Lack of attraction between the dispersed phase and the continuous phase (water).
138
What is coagulation in the context of colloids?
The process by which the dispersed phase of a colloid is made to aggregate and thereby separate from the continuous phase.
139
What is an example of coagulation?
Curdled milk.
140
What is the Tyndall effect?
The Tyndall effect is exhibited by colloids.
141
Why is the path of light visible through a colloid?
The path of the light is visible because it is reflected by the relatively larger-sized particles in the dispersed phase.
142
What are micelles?
Micelles are colloidal-sized particles formed when molecules or ions with both hydrophobic and hydrophilic ends are dispersed in water.
143
What is an association colloid?
An association colloid is a colloid in which the dispersed phase consists of micelles.
144
What is an example of a compound that forms micelles?
Soap, such as sodium stearate, is an example of a compound that forms micelles.
145
What are the two ends of soap molecules?
Soaps contain a nonpolar hydrocarbon end and an ionic end, which is a carboxylate group.
146
How does the hydrocarbon end of soap vary?
The length of the hydrocarbon end can vary from soap to soap.
147
148
What distinguishes electrolyte solutions from nonelectrolyte solutions?
Electrolyte solutions differ by degree of dissociation.
149
What happens to electrolytes in solution?
Electrolytes dissociate into ions, increasing the number of particles in solution.
150
How does the freezing point depression of NaCl compare to sucrose?
The freezing point depression for 0.1 m NaCl is double that for 0.1 m sucrose.
151
What is the van't Hoff factor?
The van't Hoff factor is the ratio of moles of particles in solution to moles of formula units dissolved.
152
What does the van't Hoff factor represent?
It represents the actual number of particles in solution after dissolving compared to the number of compounds involved before dissolving.
153
What is the chemical formula for hydrochloric acid?
HCl
154
What is the chemical formula for magnesium chloride?
MgCl₂
155
What is the chemical formula for potassium hydroxide?
KOH
156
What is the chemical formula for aluminum nitrate?
Al(NO₃)₃
