Chemistry: Matter and Change

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Chapter Menu
Mixtures and Solutions
Section 14.1 Types of Mixtures Section 14.2
Solution Concentration Section 14.3 Factors
Affecting Solvation Section 14.4 Colligative
Properties of Solutions
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Section 14-1
Section 14.1 Types of Mixtures

• Compare the properties of suspensions, colloids,
  and solutions.

solute a substance dissolved in a solution

• Identify types of colloids and types of
  solutions.
• Describe the electrostatic forces in colloids.

suspension colloid Brownian motion Tyndall
effect soluble miscible insoluble immiscible
Mixtures can be either heterogeneous or
homogeneous.
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Section 14-1
Heterogeneous Mixtures

• A heterogeneous mixture is a mixture that does
  not have a uniform composition and in which the
  individual substances remain distinct.

• Suspensions are mixtures containing particles
  that settle out if left undisturbed. (Like dirty
  water)

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Section 14-1
Heterogeneous Mixtures (cont.)

• Colloids are heterogeneous mixtures of
  intermediate sized particles (between 1 nm and
  1000 nm) and do not settle out.

• Colloids are categorized according to the phases
  of their particles.

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Section 14-1
Heterogeneous Mixtures (cont.)
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Section 14-1
Heterogeneous Mixtures (cont.)

• The Tyndall effect is when dispersed colloid
  particles scatter light.
• Both suspensions and solutions display this.
• Tyndall effect

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Section 14-1
Homogeneous Mixtures

• Solutions are homogeneous mixtures that contain
  two or more substances called the solute and
  solvent.

• Most solutions are liquids, but gaseous and solid
  solutions exist.

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Section 14-1
Homogeneous Mixtures (cont.)
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Section 14-1
Homogeneous Mixtures (cont.)

• A substance that dissolves in a solvent is
  soluble.

• Two liquids that are soluble in each other in any
  proportion are miscible.
• A substance that does not dissolve in a solvent
  is insoluble.
• Two liquids that can be mixed but separate
  shortly after are immiscible.

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Section 14-1
Section 14.1 Assessment
Miscible substances are A. two liquids that
are not soluble in each other B. solids that
dissolve in liquids C. solids that do not
dissolve in liquids D. two liquids that are
soluble in each other

• A
• B
• C
• D

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Section 14-1
Section 14.1 Assessment
The jerky, random movement of particles in a
liquid colloid is known as ____. A. Brownian
motion B. Tyndall effect C. Charless Law
D. kinetic energy

• A
• B
• C
• D

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• Self check quizzes

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End of Section 14-1
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Section 14-2
Section 14.2 Solution Concentration

• Describe concentration using different units.

solvent the substance that dissolves a solute to
form a solution

• Determine the concentrations of solutions.
• Calculate the molarity of a solution.

concentration molarity molality mole fraction
Concentration can be expressed in terms of
percent or in terms of moles.
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Section 14-2
Expressing Concentration

• The concentration of a solution is a measure of
  how much solute is dissolved in a specific amount
  of solvent or solution.

• Concentration can be described as concentrated or
  dilute.

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Section 2 concentration

• Many ways to express this
• by mass or volume
• like D5W which is a 5 sugar solution or normal
  saline which is 0.9 sodium chloride (table salt)
  in IV solutions
• A volume example is 70 isopropyl (rubbing)
  alcohol

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Section 14-2
Expressing Concentration (cont.)
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Section 14-2
Expressing Concentration (cont.)
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• The equation is
• Mass (or volume) of solute mass (or volume) of
  solution x 100
• How would you make up a normal saline solution?
• .9 g of NaCl up to 100 mL of water
• Do problems 9-11 page 481
• Check your answers on 1000 10)54.3 g
• Do problems 13,14 page 482 14) 2.1

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Section 14-2
Expressing Concentration (cont.)

• Molarity is the number of moles of solute
  dissolved per liter of solution.

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• Molarity ( M)is a more precise way to do
  concentration as it goes by particles not mass
• Moles of solute liters (dm3) of solution
• M mole/liter

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• What is the molarity of a normal saline solution
  0.9 g in 100 mL of water solution?
• 0.9 / 58.5 g/mol 0.0154 100ml /1000
  .1
• 0.154 M

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• What is the molarity of a D5W solution 5 g of
  dextrose (mm 180) in 100 mL of water ?
• 0.278 M

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• Do 16-19 page 483
• Answers on page 1000 16) 0.148 M 18) 0.128 M

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Preparing Molar solutions

• How do you make up 500 mL of a 0.25 molar NaCl
  solution?
• 0.25 mol/L x 0.5 L 0.125 mol
• 0.125 mol x mm(58.5 g/mol) 7.31 g of NaCl
• Put 7.31 g in a volumetric flask and dilute to
  500 mL

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• Do problems 20-22 page 484
• Check you answers on page 1000 20) 11g
  22) 30. g

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• How many grams of NaCl are dissolved in 500.0 mL
  of a 0.05M solution of NaCl?A)0.05 g B)0.29 g
  C)1.46 g D)2.92 g

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Diluting stock solutions

• Prepare 500 mL of a 0.1 M HCl solution using a 12
  M stock solution
• M1V1 M2V2
• 12 M x V1 0.1 M x 0.500 L
• V1 (0.1M x 0.500 L) 12 M
• Use 0.00417 L or 4.17 mL and dilute to 500 mL

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• Do 24 and 25 page 486
• Answers on page 1000 24) 125 mL

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Molality (m)

• To avoid the change in volume due to temperature
  a unit using mass is used
• m mol of solute / kg of solvent
• 9.00 grams of NaCl is added to (not diluted
  to)500 g of water. What is its molality
• 9/58.5 mol 0.500 kg 0.171 m

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Section 14-2
Expressing Concentration (cont.)

• Molality is the ratio of moles of solute
  dissolved in 1 kg of solvent.

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• Do 27 and 28 page 487 28) 171g answers on page
  1000

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Section 14-2
Expressing Concentration (cont.)

• Mole fraction is the ratio of the number of moles
  of solute in solution to the total number of
  moles of solute and solvent.

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Section 14-2
Section 14.2 Assessment
Which is NOT a quantitative measure of
concentration? A. molarity B. molality
C. percent by mass D. dilute

• A
• B
• C
• D

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Section 14-2
Section 14.2 Assessment
The number of moles of solute divided by liters
of solvution is called ____. A. molarity
B. molality C. percent by volume D. percent by
mass

• A
• B
• C
• D

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• Self check quizzes

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End of Section 14-2
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Section 14-3
Section 14.3 Factors Affecting Solvation

• Describe how intermolecular forces affect
  solvation.

exothermic a chemical reaction in which more
energy is released than is required to break
bonds in the initial reactants

• Define solubility.
• Understand what factors affect solubility.

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Section 14-3
Section 14.3 Factors Affecting Solvation (cont.)
solvation heat of solution unsaturated
solution saturated solution supersaturated
solution Henrys law
Factors such as temperature, pressure, and
polarity affect the formation of solutions.
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Section 14-3
The Solvation Process

• Solvation is the process of surrounding solute
  particles with solvent particles to form a
  solution.

• Solvation in water is called hydration.
• The attraction between dipoles of a water
  molecule and the ions of a crystal are greater
  than the attraction among ions of a crystal.

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Section 14-3
The Solvation Process (cont.)
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Section 14-3
The Solvation Process (cont.)

• Sucrose molecules have several OH bonds, which
  become sites for hydrogen bonding with water
  molecules.

• Oil does not form a solution with water because
  there is little attraction between polar water
  molecules and nonpolar oil molecules.

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Section 14-3
The Solvation Process (cont.)

• During solvation, the solute must separate into
  particles and move apart, which requires energy.

• The overall energy change that occurs during
  solution formation is called the heat of solution.

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Section 14-3
Factors That Affect Solvation

• Stirring or shaking moves dissolved particles
  away from the contact surfaces more quickly and
  allows new collisions to occur.

• Breaking the solute into small pieces increases
  surface area and allows more collisions to occur.
• As temperature increases, rate of solvation
  increases.

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Section 14-3
Solubility

• Solubility depends on the nature of the solute
  and solvent.

• Unsaturated solutions are solutions that contain
  less dissolved solute for a given temperature and
  pressure than a saturated solution.

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Section 14-3
Solubility (cont.)

• Saturated solutions contain the maximum amount of
  dissolved solute for a given amount of solute at
  a specific temperature and pressure.

• Solubility is affected by increasing the
  temperature of the solvent because the kinetic
  energy of the particles increases.

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Section 14-3
At what temperature is KCl saturated with 46 g?
What is the general trend for solubilities of
solids in water?
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Section 14-3
Solubility (cont.)

• A supersaturated solution contains more dissolved
  solute than a saturated solution at the same
  temperature.

• To form a supersaturated solution, a saturated
  solution is formed at high temperature and then
  slowly cooled.
• Supersaturated solutions are unstable.

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• Supersaturated demo on you tube

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Section 14-3
Solubility (cont.)
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Section 14-3
Solubility (cont.)

• Gases are less soluble in liquid solvents at high
  temperatures.

• Solubility of gases increases as its external
  pressure is increased.
• Henrys law (not tested on this) states that at a
  given temperature, the solubility (S) of a gas in
  liquid is directly proportional to the pressure
  (P).

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• Why do pop bottles foam over when they are warm
  and you shake them up?

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Section 14-3
Section 14.3 Assessment
For a given amount, which type of solution
contains the LEAST amount of solute?
A. solvated B. saturated C. supersaturated
D. unsaturated

• A
• B
• C
• D

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Section 14-3
Section 14.3 Assessment
At a given temperature, the solubility of a gas
is directly proportional to what? A. volume
B. mass C. molarity D. pressure

• A
• B
• C
• D

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• Section quiz

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End of Section 14-3
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Section 14-4
Section 14.4 Colligative Properties of Solutions

• Describe colligative properties.

ion an atom that is electrically charged

• Identify four colligative properties of
  solutions.
• Determine the boiling point elevation and
  freezing point depression of a solution.

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Section 14-4
Section 14.4 Colligative Properties of Solutions
(cont.)
colligative property vapor pressure
lowering boiling point elevation freezing point
depression osmosis osmotic pressure
Colligative properties depend on the number of
solute particles in a solution.
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Section 14-4
Electrolytes and Colligative Properties

• Colligative properties are physical properties of
  solutions that are affected by the number of
  particles but not by the identity of dissolved
  solute particles.

• Ionic compounds are electrolytes because they
  dissociate in water to form a solution that
  conducts electricity.
• Some molecular compounds are also electrolytes.

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Section 14-4
Electrolytes and Colligative Properties (cont.)

• Electrolytes that produce many ions in solution
  are strong electrolytes.

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Section 14-4
Vapor Pressure Lowering

• Adding a nonvolatile solute to a solvent lowers
  the solvents vapor pressure.

• When a solute is present, a mixture of solvent
  and solute occupies the surface area, and fewer
  particles enter the gaseous state.
• The greater the number of solute particles, the
  lower the vapor pressure.

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Section 14-4
Vapor Pressure Lowering (cont.)

• Vapor pressure lowering is due to the number of
  solute particles in solution and is a colligative
  property of solutions.

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Section 14-4
Boiling Point Elevation

• When a nonvolatile solute lowers the vapor
  pressure of a solvent, the boiling point is also
  affected. (elevated)

• More heat is needed to supply additional kinetic
  energy to raise the vapor pressure to atmospheric
  pressure.
• ?Tb Kb m ( of particles)

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Section 14-4
Freezing Point Depression

• At a solvent's freezing point temperature,
  particles no longer have sufficient kinetic
  energy to overcome interparticle attractive
  forces.

• The freezing point of a solution is always lower
  than that of the pure solvent.

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Section 14-4
Freezing Point Depression (cont.)

• Solute particles interfere with the attractive
  forces among solvent particles.

• A solution's freezing point depression is the
  difference in temperature between its freezing
  point and the freezing point of the pure solvent.
• ?Tf Kf m ( of particles)

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• Example problem 146 page 503
• What is the freezing and boiling point of a 0.029
  m solution of salt in water
• ?Tf Kf m ?Tb Kb m look at tables 14.5 and
  14.6
• 100.03 and -0.11 degrees Celsius

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• Do problems 45-47 page 503
• Answers to 45 and 47 on page 1000
• 46) 79.0 and -114.9 deg. Celcius

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Section 14-4
Osmotic Pressure

• Osmosis is the diffusion of a solvent through a
  semipermeable membrane.

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Section 14-4
Osmotic Pressure (cont.)

• Osmotic pressure is the amount of additional
  pressure caused by water molecules that moved
  that moved into the concentrated solution.

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Section 14-4
Section 14.4 Assessment
Nonvolatile solutes ____ the vapor pressure of a
solution. A. increase B. decrease C. do not
change D. unpredictably change

• A
• B
• C
• D

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Section 14-4
Section 14.4 Assessment
Colligative properties of a solution depend on
A. the type of solute B. the type of solvent
C. the vapor pressure of the solvent D. the
number of particles of solute

• A
• B
• C
• D

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• Section 4 quiz

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Study Guide 4
Section 14.4 Colligative Properties of Solutions
Key Concepts

• Nonvolatile solutes lower the vapor pressure of a
  solution.

• Boiling point elevation is directly related to
  the solutions molality.
• ?Tb Kbm
• A solutions freezing point depression is always
  lower than that of the pure solvent.
• ?Tf Kfm
• Osmotic pressure depends on the number of solute
  particles in a given volume.

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End of Section 14-4
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Study Guide 1
Section 14.1 Types of Mixtures
Key Concepts

• The individual substances in a heterogeneous
  mixture remain distinct.

• Two types of heterogeneous mixtures are
  suspensions and colloids.
• Brownian motion is the erratic movement of
  colloid particles.
• Colloids exhibit the Tyndall effect.
• A solution can exist as a gas, a liquid, or a
  solid, depending on the solvent.
• Solutes in a solution can be gases, liquids, or
  solids.

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Study Guide 2
Section 14.2 Solution Concentration
Key Concepts

• Concentrations can be measured qualitatively and
  quantitatively.

• Molarity is the number of moles of solute
  dissolved per liter of solution.

• Molality is the ratio of the number of moles of
  solute dissolved in 1 kg of solvent.

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Study Guide 2
Section 14.2 Solution Concentration (cont.)
Key Concepts

• The number of moles of solute does not change
  during a dilution.

M1V1 M2V2
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Study Guide 3
Section 14.3 Factors Affecting Solvation
Key Concepts

• The process of solvation involves solute
  particles surrounded by solvent particles.

• Solutions can be unsaturated, saturated, or
  supersaturated.
• Henrys law states that at a given temperature,
  the solubility (S) of a gas in a liquid is
  directly proportional to the pressure (P) of the
  gas above the liquid.

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Study Guide 4
Section 14.4 Colligative Properties of Solutions
Key Concepts

• Nonvolatile solutes lower the vapor pressure of a
  solution.

• Boiling point elevation is directly related to
  the solutions molality.
• ?Tb Kbm
• A solutions freezing point depression is always
  lower than that of the pure solvent.
• ?Tf Kfm
• Osmotic pressure depends on the number of solute
  particles in a given volume.

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Chapter Assessment 1
When dispersed solids in a colloid scatter light,
it is known as ____. A. Tyndall effect
B. Brownian motion C. Henrys law D. Charless
law

• A
• B
• C
• D

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Chapter Assessment 2
Molality is A. the number of moles of solute
divided by liters of solution B. the volume of
solute divided by liters of solution C. the
volume of solute divided by the volume of
solution D. the number of moles of solute
divided by kg of solvent

• A
• B
• C
• D

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Chapter Assessment 3
Which is NOT a type of solution? A. saturated
B. unsaturated C. polyunsaturated
D. supersaturated

• A
• B
• C
• D

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Chapter Assessment 4
The addition of a nonvolatile solute to a
solution A. increases the freezing point of
the solution B. increases the vapor pressure
of the solution C. lowers the boiling point of
the solution D. decreases vapor pressure of
the solution

• A
• B
• C
• D

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Chapter Assessment 5
Solutes in a solution can be A. liquids only
B. liquids and solids only C. gases and solids
only D. gases, liquids, or solids

• A
• B
• C
• D

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STP 1
Which is NOT an intensive physical property?
A. volume B. hardness C. density D. mass

• A
• B
• C
• D

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STP 2
Cl2(g) 2NO(g) ? 2NOCl is what type of reaction?
A. dehydration B. synthesis C. fusion
D. replacement

• A
• B
• C
• D

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STP 3
If 8 mol of H2 is used, how many moles of Fe will
be produced? Fe3O4(s) 4H2 ?3Fe(s) 4H2O(l)
A. 2 B. 3 C. 4 D. 6

• A
• B
• C
• D

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STP 4
Which is NOT a colligative property? A. heat of
solution B. boiling point elevation C. vapor
pressure lowering D. freezing point depression

• A
• B
• C
• D

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STP 5
Nonvolatile solutes _____ the boiling point of a
solution. A. increase B. decrease C. do not
change D. unpredictably change

• A
• B
• C
• D

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CIM
Table 14.2 Types and Examples of Solutions Figure
14.10 Dissolution of Compounds Figure
14.19 Strong, Weak, and Non-Electrolytes Figure
14.23 Osmosis
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