Pretest

1
Pretest
Chapter 8

• 1. Describe the charge and location within an
  atom of the following subatomic particles
  protons, electrons, and neutrons.
• 2. Which of the following is true of molecular
  compounds but NOT of ionic compounds?
• a. consist of two or more elements b. are found
  in nature c. contain ionic bonds d. contain
  covalent bonds

2
Pretest (continued)
Chapter 8

• 3. Conductivity, freezing point, and boiling
  point are all
• a. related to volume. b. chemical properties.
  c. physical properties. d. mass.
• 4. True or False Endothermic processes release
  energy.

3
Pretest (continued)
Chapter 8

• 5. Which of the following is always true of a
  polar covalent bond?
• a. One atom in the bond has a partial negative
  charge.b. One atom in the bond is an
  ion.c. Both atoms in the bond are of the same
  element.d. Both atoms in the bond have partial
  positive charges.
• 6. A sample of O2 gas has a mass of 64.0 grams.
  How many moles of O2 gas does the sample contain?

4
Pretest (continued)
Chapter 8

• 7. True or False Double-replacement reactions
  involve ionic compounds.
• 8. Describe chemical equilibrium in terms of
  reaction rates.

5
Interest Grabber
Section 8.1

• Observing Dissolving
• 1. Fill a clear plastic cup with water. Describe
  the physical properties of the water.
• 2. You will be given a sugar cube. Describe the
  physical properties of the sugar.
• 3. Place the sugar cube into the water. Examine
  it closely. Describe your observations.
• 4. Stir the water and sugar until you observe no
  more changes in the mixture. Describe the
  physical properties of the mixture.

6
Reading Strategy
Section 8.1

• Comparing and Contrasting

a. and b. Physical change and ions are present
before and after. c. and d. Chemical change and
ions are present after, but not before.
7
8.1 Solutions

• Solutions have two parts
• Solute substance that dissolves
• Solvent substance that solute dissolves in
• Can be a solid, liquid, or gas
• Solution takes on state of solvent
• Most familiar are those of water solvents

8
8.1

• 3 Ways substances dissolve
• Dissociation
• Dispersion
• Ionization
• Depends upon type of compound of solute

9
8.1

• Dissociation
• Occurs with ionic compounds
• Starts with ions. Results in ions
• Physical change
• Solvent attractions overcome compound attractions

10
8.1

• Dispersion
• Occurs with polar covalent compounds
• Compound breaks into smaller pieces and spreads
  out evenly
• Physical Change
• Ex Sugar and Water

11
Dispersion of Sugar in Water
Figure 4
12
Dispersion of Sugar in Water
Figure 4
13
8.1

• Ionization
• A neutral compound dissolves forming ions
• Chemical change solute reacts with solvent
• Formation of an acid/base

14
8.1

• Properties of Solutions
• Can be different from the properties of solute
  and solvent individually
• Ex
• Conductivity ability to conduct
  heat/electricity
• Increasing/Decreasing Freezing Point
• Increasing/Decreasing Boiling Point

15
8.1

• Heat of Solution
• Dissolving can be
• Exothermic- release heat
• Endothermic absorb heat

16
Factors Affecting Rates of Dissolving
Figure 7
17
Factors Affecting Rates of Dissolving
Figure 7
18
Factors Affecting Rates of Dissolving
Figure 7
19
Factors Affecting Rates of Dissolving
Figure 7
20
8.1

• Factors that speed up (alter) rate of dissolving
• Heat/Temperature
• Surface Area
• Stirring
• Collision Theory the more collisions, the
  faster the reaction will occur!!!

21
8.1

• Reviewing Concepts
• 1.   What are three ways that substances can
  dissolve in water?
• 2.   What physical properties of a solution
  differ from those of its solutes and solvent?
• 3.   How does the formation of a solution involve
  energy?
• 4.   What factors affect dissolving rates?

22
8.2 Solution Concentration Activity Requirements

• Lab ID
• Lab Title
• Lab Objectives/Purpose
• Data Table
• Add a column to the right, as you taste each
  solution, make observations about taste.
• 3 Analysis Questions
• Conclusion Statement

23
Interest Grabber
Section 8.2

• Solute Concentration
• You will be provided with five clear plastic
  cups, colored drink mix, measuring spoons, and
  water. Copy the table below onto a piece of
  paper. Label the plastic cups 15. In each of the
  cups, dissolve the given amounts of solute into
  the corresponding amounts of solvent according to
  the table.

1. Rate each solution with a number 14 that
corresponds to the intensity of its color (1
least intense, 4 most intense). In the table,
fill in the color intensity rating for each
solution.
Cup Solute Amount Solvent Amount Color Intensity Rating
1 ½ teaspoon 250 mL
2 1 teaspoon 250 mL
3 2 teaspoons 250 mL
4 4 teaspoons 250 mL
5 1 teaspoon 125 mL
cup 1 1, cup 2 2, cup 3 3, cup 4 4, cup
5 3
Click the mouse button to display the answer.
24
Interest Grabber (continued)
Section 8.2

• Solute Concentration
• You will be provided with five clear plastic
  cups, colored drink mix, measuring spoons, and
  water. Copy the table below onto a piece of
  paper. Label the plastic cups 15. In each of the
  cups, dissolve the given amounts of solute into
  the corresponding amounts of solvent according to
  the table.

2. Describe the relationship between the amount
of solute contained in the solution and the color
intensity of the solution.
In general, as the amount of solute added
increases, so does the color intensity of the
solution.
Cup Solute Amount Solvent Amount Color Intensity Rating
1 ½ teaspoon 250 mL
2 1 teaspoon 250 mL
3 2 teaspoons 250 mL
4 4 teaspoons 250 mL
5 1 teaspoon 125 mL
Click the mouse button to display the answer.
25
Interest Grabber (continued)
Section 8.2

• Solute Concentration
• You will be provided with five clear plastic
  cups, colored drink mix, measuring spoons, and
  water. Copy the table below onto a piece of
  paper. Label the plastic cups 15. In each of the
  cups, dissolve the given amounts of solute into
  the corresponding amounts of solvent according to
  the table.

3. Are there any exceptions to the relationship
you observed? Explain
Yes. In cup 5, the amount of solute is the same
as the amount in cup 2, but the color intensity
rating of cup 5 is same as that of cup 3. This
difference can be explained by the fact that half
the usual amount of solvent was used for the
solution in cup 5. For a given volume, as the
amount of solute increases, so does the color
intensity of the solution.
Cup Solute Amount Solvent Amount Color Intensity Rating
1 ½ teaspoon 250 mL
2 1 teaspoon 250 mL
3 2 teaspoons 250 mL
4 4 teaspoons 250 mL
5 1 teaspoon 125 mL
Click the mouse button to display the answer.
26
Reading Strategy
Section 8.2

• Previewing

a. the maximum amount of solute that dissolves in
a given amount of solvent at a given temperature
b. What factors affect solubility? c. and d.
How is the concentration of a solution expressed?
percent by volume, percent by mass, molarity
27
8.2

• Solubility maximum amount of solute that will
  dissolve in a given volume of solvent (at a
  constant temp)
• Unsaturated solution with under maximum amount
  of solute
• Saturated solution with exactly maximum amount
  of solute
• Supersaturated solution with super (more) than
  maximum amount of solute
• Very unstable

28
8.2

• Factors that affect Solubility
• Polarity
• Like dissolves like
• Pressure
• Increase increased solubility
• Temperature
• Increase increased solubility

29
8.2

• Concentration measured amount of solute in
  solvent
• Can be expressed 3 ways
• Percent by Volume (20/80)
• Percent by Mass (2g/8g)
• Molarity

30
Solubility of Some Common Substances
Figure 8
31
8.2

• Reviewing Concepts
• 1.   What terms are used to describe solutions
  with different amounts of solute?
• 2.   List three factors that affect solubility.
  
• 3.   What are three ways to measure the
  concentration of a solution?
• 4.  What is the effect of pressure on the
  solubility of a gas?

32
Interest Grabber
Section 8.3

• Acidic, Basic, or Neutral
• 1. Place three strips of universal indicator
  paper on a paper towel. Dip a clean stirring rod
  into a solution of saltwater. Touch a drop of
  saltwater onto one strip of indicator paper.
  Rinse the stirring rod in deionized water. Record
  your observations.
• 2. Dip the clean stirring rod into the ammonia
  cleaning solution. Touch a drop of the ammonia
  solution onto the second strip of indicator
  paper. Rinse the stirring rod in deionized water.
  Record your observations.
• 3. Dip the clean stirring rod into the vinegar.
  Touch a drop of the vinegar onto the third strip
  of indicator paper. Record your observations.
• 4. Refer to the color chart provided with the
  indicator paper. Your teacher will explain which
  colors indicate an acid, which colors indicate a
  base, and which color indicates a neutral
  solution. Classify each solution as acidic,
  basic, or neutral.

33
Reading Strategy
Section 8.3
Using Prior Knowledge

• b. a compound that produces hydronium ions when
  dissolved in water
• d. a compound that produces hydroxide ions when
  dissolved in water
• f. any ionic compound that forms when an acid
  reacts with a base

34
Common Acids and Their Uses
Figure 15
Acetic acid CH3COOH Vinegar
Carbonic acid H2CO3 Carbonated beverages
Hydrochloric acid HCI Digestive juices in stomach
Nitric acid HNO3 Fertilizer production
Phosphoric acid H3PO4 Fertilizer production
Sulfuric acid H2SO4 Car batteries
35
Common Bases and Their Uses
Figure 17
Aluminum hydroxide Al(OH)3 Deodorant, antacid
Calcium hydroxide Ca(OH)2 Concrete, plaster
Magnesium hydroxide Mg(OH)2 Antacid, laxative
Sodium hydroxide NaOH Drain cleaner, soap
production
36
Common Salts and Their Uses
Figure 19
Sodium chloride NaCl Food flavoring, preservative
Sodium carbonate Na2CO3 Used to make glass
Potassium chloride KCl Used as a salt substitute
to reduce dietary intake of sodium
Potassium iodide Kl Added to table salt to
prevent iodine deficiency
Magnesium chloride MgCl2 De-icer for roads
Calcium carbonate CaCO3 Chalk, marble floors, and
tables
Ammonium nitrate NH4NO3 Fertilizer, cold packs
37
Interest Grabber
Section 8.4

• Concentration
• Bottled fruit juice often contains pure fruit
  juice, sugar, and other ingredients dissolved in
  water. The concentration of pure fruit juice can
  vary with the brand. Look at five different
  samples of juice made from the same fruit. The
  label of each bottle or carton should tell you
  the concentration (percent by volume) of pure
  fruit juice in the beverage.
• 1. List the concentrations of all five juice
  samples.
• 2. Pour a small sample of the juice with the
  highest concentration and the juice with the
  lowest concentration. Taste each juice. What
  can you conclude about the relationship
  between the concentration of pure juice and
  the taste of the juice?

38
Reading Strategy
Section 8.4

• Comparing and Contrasting

a. ionizes almost completely when dissolved in
water b. is a strong electrolyte c. dissociates
almost completely when dissolved in water
39
The pH Scale
Figure 22
40
Pretest Answers
Chapter 8

• 1. Describe the charge and location within an
  atom of the following subatomic particles
  protons, electrons, and neutrons.
• 2. Which of the following is true of molecular
  compounds but NOT of ionic compounds?
• a. consist of two or more elements b. are found
  in nature c. contain ionic bonds d. contain
  covalent bonds

Protons are positive and located in the nucleus.
Electrons are negative and surround the nucleus
in an electron cloud. Neutrons are neutral and
are located in the nucleus.
Click the mouse button to display the answers.
41
Pretest Answers (continued)
Chapter 8

• 3. Conductivity, freezing point, and boiling
  point are all
• a. related to volume b. chemical properties
  c. physical properties d. mass
• 4. True or False Endothermic processes release
  energy.

Click the mouse button to display the answers.
42
Pretest Answers (continued)
Chapter 8

• 5. Which of the following is always true of a
  polar covalent bond?
• a. One atom in the bond has a partial negative
  charge.b. One atom in the bond is an
  ion.c. Both atoms in the bond are of the same
  element.d. Both atoms in the bond have partial
  positive charges.
• 6. A sample of O2 gas has a mass of 64.0 grams.
  How many moles of O2 gas does the sample contain?

2.00 moles
Click the mouse button to display the answers.
43
Pretest Answers (continued)
Chapter 8

• 7. True or False Double-replacement reactions
  involve ionic compounds.
• 8. Describe chemical equilibrium in terms of
  reaction rates.

Chemical equilibrium is a state in which the
forward and reverse reactions are taking place at
the same rate.
Click the mouse button to display the answers.
44
Interest GrabberAnswers
Section 8.1

• 1. Fill a clear plastic cup with water. Describe
  the physical properties of the water.
• Water is a clear, colorless liquid at room
  temperature.
• 2. You will be given a sugar cube. Describe the
  physical properties of the sugar.
• The sugar has white, solid crystals that have
  been pressed into a cubical shape.
• 3. Place the sugar cube into the water. Examine
  it closely. Describe your observations.
• The sugar mixes with the water making clear
  trails in the water. The cube breaks up and gets
  smaller over time.
• 4. Stir the water and sugar until you observe no
  more changes in the mixture. Describe the
  physical properties of the mixture.
• The sugar is no longer visible. The mixture
  appears to have the same properties as the pure
  water. It is a clear, colorless liquid.

45
Interest GrabberAnswers
Section 8.3

• 1. Place three strips of universal indicator
  paper on a paper towel. Dip a clean stirring rod
  into a solution of saltwater. Touch a drop of
  saltwater onto one strip of indicator paper.
  Rinse the stirring rod in deionized water. Record
  your observations.
• The indicator paper turns green.
• 2. Dip the clean stirring rod into the ammonia
  cleaning solution. Touch a drop of the ammonia
  solution onto the second strip of indicator
  paper. Rinse the stirring rod in deionized water.
  Record your observations.
• The indicator paper turns blue.
• 3. Dip the clean stirring rod into the vinegar.
  Touch a drop of the vinegar onto the third strip
  of indicator paper. Record your observations.
• The indicator paper turns orange.
• 4. Refer to the color chart provided with the
  indicator paper. Your teacher will explain which
  colors indicate an acid, which colors indicate a
  base, and which color indicates a neutral
  solution. Classify each solution as acidic,
  basic, or neutral.
• Saltwater is neutral. Ammonia solution is basic.
  Vinegar is acidic.

46
Interest GrabberAnswers
Section 8.4

• 1. List the concentrations of all five juice
  samples.
• Concentrations will vary.
• 2. Pour a small sample of the juice with the
  highest concentration and the juice with the
  lowest concentration. Taste each juice. What can
  you conclude about the relationship between the
  concentration of pure juice and the taste of the
  juice?
• Juices with high concentrations of pure juice
  taste more like the fruit they come from. Juices
  with low concentrations taste watery or sugary.

47
Chapter 8
Go Online
Self-grading assessment For links on solutions,
go to www.SciLinks.org and enter the Web Code as
follows ccn-1081. For links on bases, go to
www.SciLinks.org and enter the Web Code as
follows ccn-1083. For links on pH, go to
www.SciLinks.org and enter the Web Code as
follows ccn-1084.
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