STAAR Chemistry Book

TEKS

Boston, Massachusetts Chandler, Arizona Glenview, Illinois Upper Saddle River, New Jersey

Texas STAAR Review & Practice

Chemistry

STR12_ANC_CHEM_FM.indd 1 2/14/12 9:58 AM

Copyright 2012 Pearson Education, Inc., or its affiliates. All Rights Reserved. Printed in the United States of America. This publication is protected by copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to Rights Management & Contracts, Pearson Education, Inc., One Lake Street, Upper Saddle River, New Jersey 07458.

ISBN-13: 978-0-13-319135-6

ISBN-10: 0-13-319135-4

1 2 3 4 5 6 7 8 9 10 V088 15 14 13 12

Content Reviewer

C. Alton Hassell, Ph.D.Director of Undergraduate Programs, Chemistry and BiochemistryBaylor UniversityWaco, Texas


TEKSREVIEW

Contents

About this Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Texas Essential Knowledge and Skills (TEKS) for Chemistry . . . . . . . . . . . . . . . . . vii

Lesson Reviews

TEKS .1A . Demonstrating .Safe .Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

TEKS .1B . Hazards .of .Chemical .Substances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

TEKS .1C . Conservation .of .Resources .and .Proper .Disposal . . . . . . . . . . . . . . . . . . . . 7

TEKS .2A . Definition .of .Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

TEKS .2B . Scientific .Hypotheses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

TEKS .2C . Scientific .Theories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

TEKS .2D . Scientific .Hypotheses .and .Scientific .Theories . . . . . . . . . . . . . . . . . . . . . 19

TEKS .2E . Planning .and .Implementing .Investigative .Procedures . . . . . . . . . . . . . . 22

TEKS .2F . Accuracy .and .Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

TEKS .2G . Dimensional .Analysis, .Scientific .Notation, .and .Significant .Figures . . . . 28

TEKS .2H . Data .Analysis, .Inferences, .and .Predictions . . . . . . . . . . . . . . . . . . . . . . . 31

TEKS .2I . Communicating .Conclusions .Based .on .Scientific .Data . . . . . . . . . . . . . . 34

TEKS .3A . Analyzing, .Evaluating, .and .Critiquing .Scientific .Explanations . . . . . . . 37

TEKS .3B . Communicating .and .Applying .Scientific .Information . . . . . . . . . . . . . . 40

TEKS .3C . Drawing .Inferences .from .Promotional .Materials . . . . . . . . . . . . . . . . . . 43

TEKS .3D . The .Impact .of .Scientific .Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

TEKS .3E . Chemistry .and .Careers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

TEKS .3F . The .History .of .Chemistry .and .Contributions .of .Scientists . . . . . . . . . . . 52

TEKS .4A . Physical .and .Chemical .Changes .and .Properties . . . . . . . . . . . . . . . . . . . 55

TEKS .4B . Intensive .and .Extensive .Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

TEKS .4C . States .of .Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

TEKS .4D . Classifying .Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

TEKS .5A . Development .of .the .Periodic .Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

TEKS .5B . Chemical .Families .in .the .Periodic .Table . . . . . . . . . . . . . . . . . . . . . . . . . 70

TEKS .5C . Trends .in .the .Periodic .Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

TEKS .6A . Atomic .Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

TEKS .6B . Electromagnetic .Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

TEKS .6C . Calculating .Wavelength, .Frequency, .and .Energy .of .Light . . . . . . . . . . . 82

TEKS .6D . Calculating .Average .Atomic .Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

TEKS .6E . Electron .Configurations .and .Lewis .Valence .Electron .Dot .Structures . . 88

TEKS .7A . Naming .Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

TEKS .7B . Writing .Chemical .Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

iii


TEKS 7C Constructing Electron Dot Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

TEKS 7D The Nature of Metallic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

TEKS 7E Molecular Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

TEKS 8A Defining and Using the Mole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

TEKS 8B Calculating Atoms, Ions, or Molecules Using Moles . . . . . . . . . . . . . . 109

TEKS 8C Calculating Percent Composition, Empirical Formulas, and Molecular Formulas . . . . . . . . . . . . . . . . . . . 112

TEKS 8D Balancing Chemical Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

TEKS 8E Stoichiometric Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

TEKS 9A Gas Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

TEKS 9B Gas Stoichiometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

TEKS 9C Kinetic Molecular Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

TEKS 10A The Importance of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

TEKS 10B Solubility Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

TEKS 10C Calculations Involving Molarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

TEKS 10D Calculating Dilutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

TEKS 10E Types of Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

TEKS 10F Factors Influencing Solubility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

TEKS 10G Acids and Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

TEKS 10H Types of Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

TEKS 10I pH of a Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

TEKS 10J Degrees of Dissociation for Acids and Bases . . . . . . . . . . . . . . . . . . . . 157

TEKS 11A Energy and Its Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

TEKS 11B Conservation of Energy and Heat Transfer . . . . . . . . . . . . . . . . . . . . . 163

TEKS 11C Energy Changes in Chemical Reactions . . . . . . . . . . . . . . . . . . . . . . . . 166

TEKS 11D Heat, Mass, Temperature Change, and Specific Heat . . . . . . . . . . . . . 169

TEKS 11E Calorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

TEKS 12A Alpha, Beta, and Gamma Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

TEKS 12B Describing Radioactive Decay Using Nuclear Equations . . . . . . . . . . . 178

TEKS 12C Fission and Fusion Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

Answers to End-of-Course-Assessment Reviews . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

Test-Taking Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Chemistry Reference Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

Practice Test A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Practice Test A Answer Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

Practice Test B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

Practice Test B Answer Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261


iv


TEKSREVIEW

TEKS_TXT

RE

ad

inE

SS

Use the Periodic Table to identify and explain periodic trends, including atomic and ionic radii, electronegativity, and ionization energy.RE

ad

inE

SS

5C Trends in the Periodic TableTEKS 5C

What periodic trends in atomic radii can be identified in the periodic table?The size of an atom is expressed as an atomic radius (plural, radii). The atomic radius is one half the distance between the nuclei of two atoms of the same element when the atoms are joined. In general, atomic radii decrease from left to right across a period on the periodic table and increase from top to bottom within a group, or family. As you move across a period in the periodic table, the number of protons in the atoms increases, but the electrons remain in the same energy level. Therefore, outer-level electrons are pulled more strongly toward the nucleus from left to right across a period. This increasingly stronger pull results in a smaller radius from left to right across a period.The principal quantum number, n, of the outer-level electrons increases by one from period to period. For example, for elements in period 1, n = 1. For elements in period 2, n = 2, and so on. As n increases down a family, the outer-level electrons have an average position that is farther from the nucleus. As a result, the atoms are larger.

What periodic trends in ionic radii can be identified in the periodic table?An ion is an atom or group of atoms that has a positive or negative charge. There are two types of ionscations and anions. Cations are atoms that have lost one or more electrons and thus have a positive charge. Atoms that lose electrons become smaller. For example, the calcium ion, Ca2+, is smaller than a calcium atom, Ca, because Ca2+ has two fewer electrons.Anions are atoms that have gained one or more electrons and thus have a negative charge. Atoms that gain electrons are bigger. For example, a bromide ion, Br, is larger than a bromine atom, Br, because Br has one more electron. Cations and anions exhibit trends that are similar to those of their parent atoms across periods and down families. From left to right across a period, the radii of cations and anions decrease because the number of protons in the nucleus increases. From top to bottom within a family, the radii of cations and anions increase because the principal quantum number, n, increases.

Vocabularyatomic radiusioncationanionelectronegativityionization energy

TEKS 5C Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.73

STR12_ANC_CHEM_05C.indd 73

7/1/11 1:12 PM

A

B

Study TipDraw a rough outline of the periodic table leaving room for labels above and to the left of the table. For each trend that you study, draw a line above the table and on the left side, and use arrowheads to indicate the direction in which the trend increases. Label each arrow.

What periodic trends in electronegativity can be identified in the periodic table?Electronegativity is the ability of an atom to attract electrons when the atom is in a compound. The greater an atoms electronegativity, the greater its ability to attract electrons. The number of protons in the nucleus and the principal quantum number influence the periodic trends for electronegativity. Generally, the electronegativity increases from left to right across a period of the periodic table because the number of protons in the nucleus increases. Electronegativity generally decreases from top to bottom within a family because outer energy level electrons are farther from the nucleus.

What periodic trends in ionization energy can be identified in the periodic table?Ionization energy is the minimum energy required to remove an electron from an atom or ion. The energy required to remove the first electron from an atom is referred to as the first ionization energy. The greater an elements ionization energy, the more difficult it is to remove an electron. Generally, ionization energy increases from left to right across a period and decreases from top to bottom within a family.

Ionization energy depends on the force of attraction the nucleus exerts on the electron. As with the other periodic trends, this attraction depends upon the number of protons in the nucleus and the distance of the electron from the nucleus. More protons exert more force, making electrons harder to remove. Therefore, from left to right across a period, ionization energy increases because the number of protons in the nucleus increases. Electrons that are closer to the nucleus are pulled more strongly toward the nucleus, making them harder to remove. Therefore, as atomic radii increase from top to bottom within a family, electrons that are farther from the nucleus are easier to remove. These trends can be seen in Figure 1 below.

Figure 1 Trends in

Ionization Energy 2500

2000

Firs

t ion

izat

ion

ener

gy (k

J/m

ol)

1500

1000

500

0 10 20 30Atomic number

40 50 60

He

H Be

N

Ne

Li Na

Mg

PZn As Cd

K Rb Cs

KrXe

Ar

First Ionization Energy vs. Atomic Number

TEKS 5C Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

74

STR12_ANC_CHEM_05C.indd 74 7/1/11 1:12 PM

C

End-of-Course Assessment Review

1.Identify Which of the following trends can be identified on the periodic table?A Atomic radii increase from left to right across a period.

B Ionization energy increases from top to bottom within a family.

C Electronegativity decreases from left to right across a period.

D Ionic radii of cations decreases from left to right across a period.

2.Explain Which of the following correctly explains why the sizes of atoms decrease from left to right across a period?A The principal quantum number increases.

B The number of electrons increases.

C The distance from the nucleus increases.

D The number of protons increases.

3.Explain An increase in principal quantum number explains which of the following trends?A The ionization energy decreases from top to bottom within a family.

B The ionization energy increases from left to right across a period.

C The electronegativity increases from left to right across a period.

D The atomic radius increases from left to right across a period.

4.ApplyConcepts Use the table below to determine which of the following relationships is correct.

A Li has a smaller atomic radii than C.

B Li+ has a larger atomic radii than Li.

C Rb has a smaller atomic radii than Li.

D Li has a larger atomic radii than Be.

5.Explain Why does an increase in the number of protons in the nucleus of an atom increase the ionization energy of atoms within a period?

TEKS

LiCRbBe

2252

1A4A1A2A

Selected Trends in the Periodic TableElement Period Family


75


D

TEKSEach three-page lesson begins with the TEKS. Readiness standards, which have been identified as those most important for in-depth understanding of a particular topic, are clearly indicated. The content summaries specifically address the concepts called out in the TEKS. The lessons include numerous illustrations to help you visualize and understand the concepts and vocabulary of chemistry. You should carefully review the illustrations as well as the explanations within the text.

VocabularyYou will need to know the definitions of the vocabulary words listed at the beginning of each lesson in order to answer many of the end-of-course assessment questions. These words are shown in bold type within the topic where they are first defined. Each bold word is accompanied by a simple definition in the text. Vocabulary words are also defined in the glossary at the end of the book. Words that are in italicized type are words that you need to know to understand basic chemistry concepts. Although you are not likely to be tested on the specific definitions of non-vocabulary words, these words may be used in end-of-course assessment questions.

Study TipEach lesson contains a study tip that either refreshes your memory of relevant information that may have been covered in previous science courses or helps reinforce understanding of a particular concept.

End-of-Course Assessment Review QuestionsFollowing each content summary is a set of questions that will help you clarify and reinforce your understanding of the content. Answering these questions will help gauge your understanding of a particular TEKS. Answers and

explanations can be found at the end of the book.

About this BookThis review and practice book focuses on the basic content that may be tested on the end-of-course State of Texas Assessments of Academic Readiness (STAAR) in Chemistry. Each Texas Essential Knowledge and Skills (TEKS) is reviewed in sequence. You can use the book in any order, as each TEKS review is independent.

A

B

C

D


v


TEKSREVIEW

TEKS_TXTCalculate the wavelength, frequency, and energy of light using Plancks constant and the speed of light.

6CCalculating Wavelength, Frequency, and Energy of Light

TEKS 6C

How can you calculate the wavelength of light using its frequency and the speed of light?In a vacuum, all electromagnetic waves, including light waves, travel at the speed of light. The speed of light, c, is a constant value of 300,000,000 meters per second (3.00 108 m/s). The product of the wavelength, , and frequency, , of a wave equals the speed of light, c.

c =

Because the product of wavelength and frequency is equal to a constant, you can always calculate one of these variables if you know the value of the other. For example, if you know the frequency of a wave, you can calculate its wavelength by dividing both sides of the equation by frequency. The result is:

= c

Study TipKeep track of units as you do your calculations. Knowing the units of the value that you are calculating can help you determine which equation to use.

Sample Problem 1Visible light has frequencies between about 4.0 1014 hertz (Hz) and about 7.9 1014 Hz. What are the wavelengths of the lowest frequencies of visible light?

First, substitute the lowest frequency, 4.0 1014 Hz, into the equation:

= c

4.0 1014 Hz

Next, substitute the speed of light for c:

= 3.00 108 m/s

4.0 1014 Hz

Notice that, in this form, the units do not cancel. Recall that 1 Hz equals 1 s1. Substitute 1 s1 for the unit Hz:

= 3.00 108 m/s

4.0 1014 s1

Multiplying the numerator and denominator by s leaves only the unit of m. Divide 3.00 108 m by 4.0 1014.

= 3.00 108 m

4.0 1014

Recall that the exponent of the denominator, 14, is subtracted from the exponent of the numerator, 8.

= 0.75 106 m or 7.5 107 m

The longest wavelengths of visible light are about 7.5 107 m.


82

STR12_ANC_CHEM_06C.indd 82 7/25/11 8:03 AM

E


205

Interpreting DiagramsScientists use diagrams to show the parts of objects or the steps of a process. Begin by looking carefully at the diagram to get an overall sense of what it shows. Look for any labels with lines connected to parts of the diagram. If you dont immediately recognize what the diagram shows, the labels may give you a clue. After you have examined the diagram, read the question. After you choose an answer, recheck the diagram to make sure that your answer is correct.

Sometimes you will be asked to interpret a set of related diagrams. Each part of the diagram could represent a test group of a science experiment or demonstration. Or the diagrams could show the steps of a process, such as a chemical reaction.

To interpret a set of diagrams, make sure that you understand the meaning of arrows and other symbols. You should also compare the different diagrams. Determine the features that are similar and different. Then read the question and answer choices carefully.

Sample Question 1In the diagram below, which feature of protons, neutrons, and electrons is represented most accurately?

Proton

Neutron

Electron

A position inside or outside of the atomic nucleus

B distance between them

C markings on their surfaces

D relative sizes

The correct answer is A. To identify the correct answer, you need to apply some basic facts about atoms. As choice A and the diagram suggest, protons and neutrons are located in the atomic nucleus. Electrons move in the space around the nucleus. Choices B, C, and D are all features that the diagram does not represent accurately about atoms. Remember that all models are inaccurate in at least some ways.

Sample Question 2Four identical bottles of carbonated water are each placed in a glass bowl. The conditions of the bowl and the bottle are shown in the set of diagrams below.

Cap

Ice

Bottle 1

Cap

Warm water

Bottle 2

No cap

Ice

Bottle 3

No cap

Warm water

Bottle 4

Which bottle will contain the least amount of dissolved carbon dioxide after 15 minutes?

A Bottle 1 C Bottle 3

B Bottle 2 D Bottle 4

The correct answer is D. Bottle 4 is uncapped, so the carbon dioxide in Bottle 4 is under less pressure than the carbon dioxide in Bottles 1 and 2. Because the solubility of a gas decreases as the pressure decreases, Bottle 4 will contain less carbon dioxide than Bottles 1 and 2. The warm water surrounding Bottle 4 also decreases the solubility of carbon dioxide. Bottle 3 is uncapped like Bottle 4, but is sitting in ice.

STR12_ANC_CHEM_EM.indd 205 1/18/12 2:53 PM

F

TEKS

Total pressure of a gas = sum of the partial pressures

of the component gases P P P PT . . .= + + +1 2 3( ) (Pressure)(volume) = (moles)(ideal gas constant)(temperature) PV nRT=

Molaritymoles of soluteliter of solution

= M = molL

Ionization constant of water = hydrogen ion concentrationhydroxide ion concentration

Kw

+[H ][OH ]= ( )( )( Volume of solution 1 molarity of solution 1 = volume of solution 2 molarity of solution 2 V M V M1 1 2 2=)( ) ( )( )

ATOMIC STRUCTURE

BEHAVIOR OF GASES

SOLUTIONS

(Initial volume)(Initial temperature)

(final vo=

llume)

(final temperature)

VT

VT

1

1

2

2=

(Initial pressure)(initial volume) = (final pressure)(final volume) PV PV1 1 2 2=

(Initial pressure)(initial volume)

(Initial moless)(initial temperature)

(final pressure)(final=

volume)

(final moles)(final temperature)

PVnT

PVn T

1 1

1 1

2 2

2 2=

(Initial volume) (final volume)

(Initial moles) (final moles)=

Vn

Vn

1

1

2

2=

Heat gained or lost = (mass) specific heat

change in temperature

Q mc T=p( )( )

= enthalpy

of products enthalpy

of reactants H H H= fo

fo(products) (reactants)

Enthalpy of reaction ( ) ( )

THERMOCHEMISTRY

pH = logarithm (hydrogen ion concentration) pH log[H ]= +

Speed of light = (frequency)(wavelength) c f=

Energy = (Plancks constant)(frequency) Ephoton hf=

Energy = (Plancks constant)(speed of light)

(wavelength)Ephoton

hc=

STAAR CHEMISTRY REFERENCE MATERIALS State of Texas Assessments of

Academic Readiness

STAARTMREVIEW

Chemistry Reference Materials

ATOMIC STRUCTURE

BEHAVIOR OF GASES

SOLUTIONS

THERMOCHEMISTRY

209

STR12_ANC_CHEM_EM_RM.indd 209 2/13/12 1:28 PM

G

TEKS

STAAR Chemistry

Practice Test A

Copyright Pearson Education, Inc., or its affiliates.

All Rights Reserved.

End-of-Course Assessment

Chemistry Practice Test A

1 A student performs the following tests to de

termine the identity of a mineral sample from its

physical and chemical properties.

Test 1 Microscopic examination of the mineral

to see the shape of its crystals

Test 2 Scratch test of the mineral to determine

its hardness

Test 3 Rubbing the mineral on a streak plate to

determine the color of its

powdered form

Test 4 Dropping dilute hydrochloric acid on the

mineral to see if bubbles will form

Which of the tests would involve a chemical chang

e in the mineral?

A Tests 2 and 4

B Tests 3 and 4

C Tests 1, 2, and 4

D Test 4 only

2 A chemistry student makes careful observatio

ns and measurements of a small sample

of matter, and determines the following:

Appearance silver solid

Mass 11.85 g

Density 5.9 g/cm3

Melting point 30C

The student determines that the unknown substa

nce is gallium (Ga). Which of the following

is an extensive property of the gallium sample?

A Silver solid

B Mass of 11.85 g

C Density of 5.9 g/cm3

D Melting point of 30C

215

STR12_ANC_CHEM_EM_PTA.indd 215

2/7/12 11:04 AM

TEKS

STAAR Chemistry Practice Test B


End-of-Course AssessmentChemistry Practice Test B

1 A student performs the following tests to determine the identity of a mineral sample.

1. The mineral is heated in chlorine gas to see if it will produce a different substance.

2. The mineral is immersed in an ammonia solution to see if any new color is produced.

3. The mineral is rubbed on a streak plate to determine the color of its powdered form.

4. Dilute hydrochloric acid is placed on the mineral to see if bubbles will form.

Which of the above tests were for physical properties of the mineral?

A Test 1

B Test 2

C Test 3

D Test 4

2 A sample of sulfur obtained from the crater of a volcano is carefully measured. Which of the following is an intensive property of the sample?

A Density of 2.07 g/cm3

B Mass of 3.85 g

C Volume of 1.86 cm3

D Temperature of 20C

239

STR12_ANC_CHEM_EM_PTB.indd 239 2/7/12 11:05 AM

H

Sample ProblemsNumerous solved sample problems appear throughout this book to provide you with examples of typical problems found on the end-of-course assessment. The step-by-step detailed solutions guide you in the problem-solving process and help reinforce content knowledge.

Test-Taking TipsTest-taking tips provide strategies for answering multiple-choice questions. Accompanying sample questions allow you to practice your test-taking skills.

Reference MaterialsChemistry reference materials include formulas, constants, conversions, the periodic table, and other information that may be needed to answer questions on the exam. You will get a copy of these reference materials when you take your end-of-course test.

Practice TestsTwo sample full-length exams mimic the STAAR test in both format and layout. Following each test is an answer sheet for you to fill in the correct answers.

E

F

G

H


vi


(1) Scientific processes. The student, for at least 40% of instructional time, conducts laboratory and field investigations using safe, environmentally appropriate, and ethical practices. The student is expected to:

(A) Demonstrate safe practices during laboratory and field investigations, including the appropriate use of safety showers, eyewash fountains, safety goggles, and fire extinguishers.

(B) Know specific hazards of chemical substances such as flammability, corrosiveness, and radioactivity as summarized on the Material Safety Data Sheets (MSDS).

(C) Demonstrate an understanding of the use and conservation of resources and the proper disposal or recycling of materials.

es

(3) Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to:

(A) In all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student.

(B) Communicate and apply scientific information extracted from various sources such as current events, news reports, published journal articles, and marketing materials.

(C) Draw inferences based on data related to promotional materials for products and services.

(D) Evaluate the impact of research on scientific thought, society, and the environment.

(E) Describe the connection between chemistry and future careers.

(F) Research and describe the history of chemistry and contributions of scientists.

Texas Essential Skills and Knowledge (TEKS) for Chemistry

(2) Scientific processes. The student uses scientific methods to solve investigative questions. The student is expected to:

(A) Know the definition of science and understand that it has limitations.

(B) Know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories.

(C) Know that scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations, but may be subject to change as new areas of science and new technologies are developed.

(D) Distinguish between scientific hypotheses and scientific theories.

(E) Plan and implement investigative procedures, including asking questions, formulating testable hypotheses, and selecting equipment and technology, including graphing calculators, computers and probes, sufficient scientific glassware such as beakers, Erlenmeyer flasks, pipettes, graduated cylinders, volumetric flasks, safety goggles, and burettes, electronic balances, and an adequate supply of consumable chemicals.

(F) Collect data and make measurements with accuracy and precision.

(G) Express and manipulate chemical quantities using scientific conventions and mathematical procedures, including dimensional analysis, scientific notation, and significant figures.

(H) Organize, analyze, evaluate, make inferences, and predict trends from data.

(I) Communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphs, journals, summaries, oral reports, and technology-based reports.


vii


(4) Science concepts. The student knows the characteristics of matter and can analyze the relationships between chemical and physical changes and properties. The student is expected to:

(A) Differentiate between physical and chemical changes and properties. Readiness Standard

(B) Identify extensive and intensive properties. Supporting Standard

(C) Compare solids, liquids, and gases in terms of compressibility, structure, shape, and volume. Supporting Standard

(D) Classify matter as pure substances or mixtures through investigation of their properties. Readiness Standard

(7) Science concepts. The student knows how atoms form ionic, metallic, and covalent bonds. The student is expected to:

(A) Name ionic compounds containing main group or transition metals, covalent compounds, acids, and bases, using International Union of Pure and Applied Chemistry (IUPAC) nomenclature rules.

Readiness Standard

(B) Write the chemical formulas of common polyatomic ions, ionic compounds containing main group or transition metals, covalent compounds, acids, and bases.

Readiness Standard

(C) Construct electron dot formulas to illustrate ionic and covalent bonds. Readiness Standard

(D) Describe the nature of metallic bonding and apply the theory to explain metallic properties such as thermal and electrical conductivity, malleability, and ductility.

Supporting Standard

(E) Predict molecular structure for molecules with linear, trigonal planar, or tetrahedral electron pair geometries using Valence Shell Electron Pair Repulsion (VSEPR) theory.

Supporting Standard

(5) Science concepts. The student understands the historical development of the Periodic Table and can apply its predictive power. The student is expected to:

(A) Explain the use of chemical and physical properties in the historical development of the Periodic Table.

Supporting Standard

(B) Use the Periodic Table to identify and explain the properties of chemical families, including alkali metals, alkaline earth metals, halogens, noble gases, and transition metals.

Readiness Standard

(C) Use the Periodic Table to identify and explain periodic trends, including atomic and ionic radii, electronegativity, and ionization energy.

Readiness Standard

(6) Science concepts. The student knows and understands the historical development of atomic theory. The student is expected to:

(A) Understand the experimental design and conclusions used in the development of modern atomic theory, including Daltons Postulates, Thomsons discovery of electron properties, Rutherfords nuclear atom, and Bohrs nuclear atom.

Supporting Standard

(B) Understand the electromagnetic spectrum and the mathematical relationships between energy, frequency, and wavelength of light.

Supporting Standard

(C) Calculate the wavelength, frequency, and energy of light using Plancks constant and the speed of light.

Supporting Standard

(D) Use isotopic composition to calculate average atomic mass of an element. Supporting Standard

(E) Express the arrangement of electrons in atoms through electron configurations and Lewis valence electron dot structures.

Readiness Standard

Chemistry TEKS continued


viii


(8) Science concepts. The student can quantify the changes that occur during chemical reactions. The student is expected to:

(A) Define and use the concept of a mole. Supporting Standard

(B) Use the mole concept to calculate the number of atoms, ions, or molecules in a sample of material. Readiness Standard

(C) Calculate percent composition and empirical and molecular formulas. Supporting Standard

(D) Use the law of conservation of mass to write and balance chemical equations. Readiness Standard

(E) Perform stoichiometric calculations, including determination of mass relationships between reactants and products, calculation of limiting reagents, and percent yield.

Supporting Standard

(9) Science concepts. The student understands the principles of ideal gas behavior, kinetic molecular theory, and the conditions that influence the behavior of gases. The student is expected to:

(A) Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyles law, Charles law, Avogadros law, Daltons law of partial pressure, and the ideal gas law.

Readiness Standard

(B) Perform stoichiometric calculations, including determination of mass and volume relationships between reactants and products for reactions involving gases.

Supporting Standard

(C) Describe the postulates of kinetic molecular theory. Supporting Standard

(10) Science concepts. The student understands and can apply the factors that influence the behavior of solutions. The student is expected to:

(A) Describe the unique role of water in chemical and biological systems. Supporting Standard

(B) Develop and use general rules regarding solubility through investigations with aqueous solutions. Readiness Standard

(C) Calculate the concentration of solutions in units of molarity. Supporting Standard

(D) Use molarity to calculate the dilutions of solutions. Supporting Standard

(E) Distinguish between types of solutions such as electrolytes and nonelectrolytes and unsaturated, saturated, and supersaturated solutions.

Readiness Standard

(F) Investigate factors that influence solubilities and rates of dissolution such as temperature, agitation, and surface area.

Readiness Standard

(G) Define acids and bases and distinguish between Arrhenius and Bronsted-Lowry definitions and predict products in acid-base reactions that form water.

Supporting Standard

(H) Understand and differentiate among acid-base reactions, precipitation reactions, and oxidation-reduction reactions.

Readiness Standard

(I) Define pH and use the hydrogen or hydroxide ion concentrations to calculate the pH of a solution. Supporting Standard

(J) Distinguish between degrees of dissociation for strong and weak acids and bases. Supporting Standard


ix


(11) Science concepts. The student understands the energy changes that occur in chemical reactions. The student is expected to:

(A) Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. Supporting Standard

(B) Understand the law of conservation of energy and the processes of heat transfer. Supporting Standard

(C) Use thermochemical equations to calculate energy changes that occur in chemical reactions and classify reactions as exothermic or endothermic.

Readiness Standard

(D) Perform calculations involving heat, mass, temperature change, and specific heat. Supporting Standard

(E) Use calorimetry to calculate the heat of a chemical process. Supporting Standard

(12) Science concepts. The student understands the basic processes of nuclear chemistry. The student is expected to:

(A) Describe the characteristics of alpha, beta, and gamma radiation. Supporting Standard

(B) Describe radioactive decay process in terms of balanced nuclear equations. Readiness Standard

(C) Compare fission and fusion reactions. Supporting Standard

Chemistry TEKS continued


x


TEKSREVIEW

What safety procedures should be followed during investigations? Because laboratory and field investigations often involve the use of hazardous or potentially hazardous materials and equipment, the risk of accidents or injury is always present. However, by following some general safety practices and procedures during investigations, accidents and injuries can be prevented.

Basic safety requirements for working in the laboratory include knowing emergency procedures and the locations of all safety equipment, following directions, and never working in the laboratory alone. It is also important to be aware of the hazards and handling procedures for all the materials and equipment you use. Other important safety policies are listed in Figure 1.

Demonstrating Safe Practices1ATEKS 1A

Demonstrate safe practices during laboratory and field investigations, including the appropriate use of safety showers, eyewash fountains, safety goggles, and fire extinguishers.

Figure 1

Notify the teacher of any sensitivities or allergies tochemicals or other substances.

Do not leave an experiment unattended.

Never chew gum, eat, or drink in the laboratory.

Always wear shoes and avoid wearing loose-tting clothing and dangling jewelry.

Secure long hair and loose clothing; roll up loosesleeves when working with burners or ames.

Inspect all equipment for damage prior to use; donot use damaged equipment.

Keep the oor clear of all objects such as personal items, spilled liquids, and any other item that may cause someone to trip or fall.

Never point the open end of a test tube containinga chemical at other people.

Do not touch any chemical with your hands.

Never inhale chemical vapors by placing thecontainer directly under your nose.

Never pour chemicals down the sink drain unlessyouve been specically instructed to do so.

When diluting an acid, always pour the acidslowly into the water, stirring to dissipate the heat. CAUTION: Never pour water into a concentrated acid.

Know the location of all emergency exits in thelaboratory and the building.

Wash your hands with soap and water at the end of each investigation.

Laboratory Safety Dos and Donts

TEKS 1A Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

1

STR12_ANC_CHEM_01A.indd 1 8/2/11 10:42 AM

Study TipLook for all symbols that represent safety equipment and protective devices in the laboratory. Learn the meaning of the symbols and purpose of each device so that you can act quickly in an emergency.

What is the appropriate use of important safety equipment? Safe practices should always be the highest priority during laboratory and field investigations. Each person has a responsibility to learn the dangers that may be present while working in the laboratory and the purpose and operation of all emergency safety equipment. Although everyone should know how to use safety equipment, a teachers instructions should always be followed in an emergency.

One of the most important safety practices is to be familiar with the proper use of protective safety devices. These devices include safety showers, fire blankets, eyewash fountains, safety goggles, aprons, gloves, and fire extinguishers. Such knowledge is vital to responding to accidents and to eliminating the risk of serious personal injury.

When is it appropriate to use a safety shower or fire blanket?Whenever the skin or clothing is exposed to a significant amount of corrosive or toxic chemicals, the contaminants must be immediately washed away with large quantities of water. An emergency safety shower is the most effective way to quickly eliminate contaminants on your skin or clothing and avoid injury. In any circumstance in which the use of a safety shower is necessary, it is important to act quickly and remove any affected articles of clothing to avoid further exposure. Once the hazardous materials have been washed away, obtain medical attention immediately.

If clothing or hair catches fire, do not run because running fans flames. A fire blanket can be used to smother flames. Or, a safety shower can be used if there is one nearby.

When is it appropriate to use safety goggles?As a rule, safety goggles should be worn at all times in the laboratory and during field investigations. During an experiment, it is likely you will use wet or dry chemicals. There is a constant danger of splashes or particles entering the eye. Safety goggles can also help protect eyes from damage due to explosions and flying debris.

When is it necessary to use an eyewash fountain? Even though the use of safety goggles is required, eyewash fountains are located in all laboratory environments where the eyes may be exposed to hazardous chemicals. In the event that one or both eyes are exposed to a hazardous substance, an eyewash fountain should be used without delay. Hold the eyelids open, and flush the affected eyes thoroughly for several minutes to ensure the substance has been purged. Then seek immediate medical attention.


2


What types of fire extinguishers are appropriate for use in laboratory environments?Not all fires are the same, and no single fire extinguisher works on every type of fire. Fires are designated by type and listed by class. The most common fire classifications, combustibles, and appropriate extinguishing agents are shown Figure 2.

Water extinguishers are never used in the laboratory as they are rated only for Class A fires. The use of a water extinguisher on a Class B, C, or D fire in the laboratory or field is extremely hazardous. Pouring water on fires involving combustible liquids, electrical equipment, or combustible metals may spread the fire or make it worse.


1.Classify If isopropyl alcohol were to catch fire in the laboratory, what class fire would this be?A.Class A

B. Class B

C.Class C

D.Class D

2.Infer If an electric hot plate caught fire in the lab, which class of fire extinguisher would you use and why?

3.Differentiate What is the appropriate personal safety response to a significant amount of corrosive liquid chemical splashed on clothing?

4.Evaluate A student says that he does not need to wear safety goggles for an experiment because no liquid chemicals are being used. What would your response be to this student?

TEKS

Figure2

Ordinary materials such as paper, wood, cardboard, and plasticsFlammable or combustible liquids such as gasoline, kerosene, and most organic solventsElectrical equipmentCombustible metals such as magnesium, potassium, and sodium

Dry chemical

CO2 or dry chemical

CO2 or dry chemicalDry powder agents

A

B

CD

Fire Classifications, Combustibles, and ExtinguishersClass Combustibles Extinguishing Agent


3


TEKSREVIEW

Why is it important to know specific hazards of chemical substances?Before working with any chemical substance, it is important to be thoroughly familiar with its properties, specific hazards, safety precautions, and handling procedures. Hazardous chemical substances are generally classified according to their hazard types as listed in Figure 1 below.

What are Material Safety Data Sheets (MSDS)? Material Safety Data Sheets (MSDS) are data forms that contain detailed information on the properties, hazards, and health effects of chemical substances. MSDS also provide guidelines for the safe handling, storage, and disposal of hazardous substances. The sheets are prepared and made available by chemical suppliers.

The U.S. Occupational Safety and Health Administration (OSHA) requires the presence of MSDS wherever hazardous materials are produced, shipped, or used. These locations include all chemistry laboratories. An MSDS includes the information listed in Figure 2.

Hazards of Chemical Substances1BTEKS 1B

Know specific hazards of chemical substances such as flammability, corrosiveness, and radioactivity as summarized on the Material Safety Data Sheets (MSDS).

VocabularyMaterial Safety Data

Sheets (MSDS)

flammable substance

corrosive substance

radioactive substance

Figure 1

TEKS 1B Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

4

Flammable/Combustible Liquids

Corrosives

Oxidizers

Water Reactives

Pyrophorics

Peroxide-forming

Compressed Gases

Cryogens

Generate vapors that will burn when ignited

Corrode metal and damage living tissues (acids, bases, and others)

Cause other materials to combust

React with water to form heat and flammable gases

Ignite spontaneously in air

Explodes if subject to shock or sparks

Disperse forcefully and quickly if released

Freeze human tissue quickly (super-cooled fluids)

Hazardous Chemical SubstancesType of Hazard Description

AcetoneMethanol

Sulfuric acid Sodium hydroxide

BromineHydrogen peroxide

Alkali metals

DiethylzincDiphsophine

Isoprophyl etherPotassium amide

OxygenAcetyleneLiquid nitrogen

Examples

STR12_ANC_CHEM_01B.indd 4 6/22/11 1:47 PM

Chemical Identity

Manufacturer

Hazardous Ingredients

Physical/Chemical Characteristics

Fire & Explosion Hazard

Reactivity

Health Hazard

Safe Handling & Use

Control Measures

Name, weight, and chemical formula

Name, address, and phone number

Hazardous components by chemical identity

Boiling point, vapor pressure, melting point, and other physical and chemical properties

Flash point, flammability limits, extinguishing method, and firefighting procedures

Stability, a list of materials and conditions to avoid, and hazardous by-products

Routes of physical entry such as inhalation, ingestion, or skin, symptoms of exposure, and emergency/first aid procedures

Precautions for handling and storage, and steps to be taken if a spill or release occurs

Protective measures for handling

Material Safety Data Sheets Section Description

1Health

2Instability

3Flammability

SpecificHazards

0 Low1 Slight2 Moderate3 High4 Extreme

In addition to Materials Safety Data sheets, many hazardous materials are also labeled with a hazard diamond, published by the National Fire Protection Association (NFPA). The NFPA warning label rates materials for health (blue), flammability (red), and instability (yellow). The three color-coded sections range from 0 (the least severe hazard) to 4 (the most severe hazard.) The bottom section is usually blank. It may be used to present specific hazards or special fire-fighting measures.

What are the specific hazards of flammable, corrosive, and radioactive substances?Flammables A flammable substance gives off combustible vapors that can easily ignite. Flammables include solids, liquids, and gases. These substances have a flash point of below 100 F. Their vapors can ignite at temperatures near room temperature.

As their MSDS specifies, flammable substances should only be used only with proper ventilation and away from heat, electric sparks, and flames. Flammable substances should also be stored in approved fire-retardant storage cabinets and should never be placed near corrosives. Flammable substances include diethyl ether, acetone, gasoline, toluene, and methyl alcohol.

Corrosives A corrosive substance is a compound that is highly reactive and will cause serious damage to living tissue. The MSDS for corrosives include warnings against contact with skin, eyes, or any part of the body. They also recommended first aid measures that include flushing a damaged area with water for up to 15 minutes, followed by immediate medical attention. Corrosives should be stored in well-ventilated areas and away from flammables and heat. Typical corrosives found in laboratories include sulfuric acid, hydrochloric acid, and sodium hydroxide.

Figure 2

Figure 3 Hazard Diamond

Study TipReview the MSDS of chemicals that you use in the laboratory. Become familiar with the format and the information presented in the forms.


5

1Health

2Instability

3Flammability

SpecificHazards

0 Low1 Slight2 Moderate3 High4 Extreme

STR12_ANC_CHEM_01B.indd 5 8/2/11 10:43 AM


6

Radioactivity Aradioactive substancespontaneouslyemitsionizingradiation.Thesesubstancesincludesolids,liquids,andgases.Dependingonthelevelofradioactivityofthesubstanceandthelevelofexposure,ionizingradiationcandamagecells,injuretissuesandorgans,andcanleadtocancer.

Useofradioactivematerialsistightlycontrolled.Anyonewhousesradioactivesubstancesmustbetrainedandcertified.Aswithallhazardoussubstances,theMSDSprovidessafehandlingproceduresandsafetyprecautions,aswellasfirstaidandcontainmentmeasures.


1.Infer ThereasonthatradioactivesubstancesaredangerousisA theywillreactviolentlywithotherchemicals.

B theradioactivitywillspreadtoanychemicalplacednearby.

C theycanburninair.

D theradioactivitycandamagelivingcells.

2.Identify Whichisacharacteristicofacorrosivesubstance?A Thesubstanceforcefullyandquicklydispersesifreleased.

B Thesubstancequicklyfreezeshumantissue.

C Thesubstanceseriouslydamagesskincellsoncontact.

D Thesubstancecausesothermaterialstocombust.

3.Evaluate Whilesomestudentsareworkinginthelab,onestudentspillsacorrosivesubstanceandaskstheotherstohelphimmopitupwithpapertowelsandcarrythemtothetrashcan.Anotherstudentobjectsandsaystheyshouldwarneveryonenearbyandinformtheinstructor.Whichapproachistheappropriatesaferesponse,andwhy?

4.Infer Giveatleastonereasonwhydiethylether,aflammableliquid,shouldnotbestoredinacommercialrefrigerator.

5.Evaluate Whyisstoringchemicalsinalphabeticalordernotasafeapproach?

TEKS


TEKSREVIEW

TEKS_TXTDemonstrate an understanding of the use and conservation of resources and the proper disposal or recycling of materials.

1CConservation of Resources and Proper Disposal

TEKS 1C

Why is the conservation of resources and proper disposal or recycling of materials important? Most natural resources are limited. Conservation of these resources will ensure that they are available for future generations. Similarly, proper disposal or recycling of waste materials is essential to maintaining human and environmental health. Figure 1 is the universal sign for recycling. But even if you see this symbol, always follow your teachers instructions regarding proper disposal or recycling of materials in the laboratory.

Waste reduction is especially important in a chemistry laboratory. Chemistry experiments involve many chemicals and they may produce hazardous wastes. One way to reduce waste is to use the smallest amounts of chemicals required whenever possible. Another way to reduce waste is to use materials that can be recovered, or recycled, instead of being discarded.

When chemicals cannot be recycled, disposal must follow strict guidelines and comply with local, state, and federal regulations. These regulations were implemented to avoid the health problems and expense caused by pollution and contamination. By effectively managing the use of materials through conservation and recycling, and by properly disposing chemical waste, both human health and the environment can be protected.

What are the proper ways to reuse and recycle materials in the laboratory?Many materials used in the laboratory can be reused after thorough cleaning and safe removal of chemical residues. These materials include containers and instruments made of sturdy glass, plastic, and metal. Materials that cannot be reused, but can be recycled, should be collected and sent to recycling plants. Recyclable items should always be discarded in containers designated for each type of material.

Before placing items in recycling containers, care should be taken to make sure they are decontaminated. Decontamination is the removal of hazardous compounds. Decontamination should only be performed under the supervision of your teacher or qualified laboratory personnel.

Vocabularydecontamination

Figure 1 Recycling Symbol


7


Some chemicals used in the laboratory can also be reused or recycled. Solvents such as acetone, methanol, and toluene are routinely reused because they can easily be purified. Chemicals that cannot be purified in the laboratory may still be good candidates for recycling because of the value of the chemical. For example, solutions containing silver ions are frequently recycled because silver is very expensive. Designated containers should always be used for each chemical to be recycled because mixing certain materials can be extremely hazardous.

What are the proper ways to dispose of materials in the laboratory?Whenever chemical substances and equipment are used in the laboratory, some waste will be generated. Because of the potential risks, very little laboratory waste can be disposed of in public waste containers. However, some laboratory consumablesmaterials that cannot be recycled and were not exposed to chemicalsmay be discarded as regular trash. Your teacher will tell you which, if any, of the lab materials you use can be disposed of in the regular trash.

Hazardous or toxic chemical wastes must be disposed of separately and according to proper guidelines for safe disposal. They also must be properly labeled. The manner in which hazardous materials are disposed of is determined by the reactive properties of each substance. The recommended disposal method for a substance is provided on its Material Safety Data Sheet (MSDS).

Chemicals such as dilute acids, bases, and certain organic compounds can be discarded by pouring them down the drain with large quantities of water. Materials that are acceptable for this disposal method are water soluble, have very low toxicity, and, if organic, are readily biodegradable. However, this type of disposal should only be performed with the approval of your teacher and after a thorough review of disposal guidelines. Figure 2 shows one example of a warning that may be found posted on some laboratory sinks. In some situations, no chemicals can be poured down a drain.

Some hazardous chemical wastes can be neutralized, or made non-hazardous. Wastes that cannot be neutralized must be shipped to a hazardous waste landfill by a licensed company approved by the Department of Transportation. You will most likely not be working with this type of chemical wastes in your chemistry labs.

Disposal of all hazardous chemical wastes must comply with local, state, and federal regulations. The federal agencies responsible for regulating waste disposal are the U.S. Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). Failure to properly dispose of chemical wastes is dangerous and unhealthy, and can result in fines and lawsuits.

Figure 2 No Disposal Sign

NOTICEDO NOT

DUMP CHEMICALSDOWN THIS DRAIN

Study TipThink about the lab investigations you performed throughout the year. Recall the disposal methods used for various chemicals and other materials.


8



1.Identify A student uses a glass beaker to mix hydrochloric acid and water in an experiment. After the experiment is complete, should she place the beaker in a recycling bin suitable for glass?A Yes. Glass beakers should always be recycled after any use.

B No. The beaker should be discarded in the trash.

C Yes. Hydrochloric acid is dangerous and any item that contains it should be recycled immediately.

D No. Glass beakers are reusable. They can easily be cleaned after an experiment and stored.

2.Analyze A researcher finishes an experiment and is unsure of how to dispose of a particular chemical. Which of the following describes the safest approach?A Contain the chemical tightly and put it in the trash.

B Combine it with other chemical waste.

C Label the chemical as Waste and leave it out for someone else to dispose of.

D Refer to the chemicals MSDS for the recommended disposal method.

3.Evaluate At the end of a laboratory experiment, a student disposes of all liquid chemicals by flushing them down the sink drain with water. Explain what is wrong with this action.

4.DemonstrateUnderstanding During an investigation, Evan spills some compound on the lab table. His lab partner tells him that the compound should be recycled. Evan collects the substance and disposes of it in a container marked for general recycling. Explain two mistakes Evan made.

5.Infer Why would a laboratory never have a single container for all waste chemicals?

TEKS


9


TEKSREVIEW

What is the definition of science?Science is the use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process. In other words, science is the study of the natural and physical world using physical, mathematical, and conceptual models.

Scientific explanations must be both testable and falsifiableable to be proven incorrect. Observation, experimentation, research, and the use of models produce evidence that allow scientists to understand natural phenomena. Scientists study patterns and make predictions about natural phenomena and processes to understand how the world works.

In many cases, because of the use of observation, experimentation, research, and models, scientists can predict the results of a natural process even if they do not have all the information about that process. Many explanations of natural processes are accepted as valid because there is so much evidence supporting them, and because they have been observed and/or tested under a wide variety of conditions. When scientific explanations have been tested and widely accepted, predictions about future events usually end up to be accurate.

Science is not the same as technology. Technology is the application of science, often for industrial or commercial uses. Science identifies how or why a natural or physical phenomenon occurs. Technology identifies how to apply that phenomenon for a practical use.

Why study science? There are many different reasons why people study science. Chemists might study compounds for potential use in medicines. Meteorologists might study weather patterns to predict hurricanes and tornadoes. Geologists might study natural processes to recognize how events in the past might influence events, such as earthquakes, in the future. Doctors, dentists, veterinarians, nurses, and pharmacists study science to provide health care to you and your pets. Physicists study the physical world from the smallest of particles to the vastness of the universe. What would you be most interested in studying through science?

Definition of Science2ATEKS 2AKnow the definition of science and understand that it has limitations, as specified in subsection (b)(2) of this section.

(b)(2) Nature of science. Science, as defined by the National Academy of Sciences, is the use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process. This vast body of changing and increasing knowledge is described by physical, mathematical, and conceptual models. Students should know that some questions are outside the realm of science because they deal with phenomena that are not scientifically testable.

Study TipRemember that scientific concepts must be part of the natural and physical world and must be testable and falsifiable. Concepts that do not fit into these categories are not scientific.


10


J. J. Thomsons model,about 1904

Ernest Rutherfordsmodel, 1911

Niels Bohrsmodel, 1913

Modern Model

++

What are the limitations of science?Because science is the study of natural and physical phenomena, science has limitations. Science is not emotion, art, or feeling. Science cannot determine which painting is more appealing or who is the best choice for president. Science cannot answer questions regarding faith or personal feelings. Such phenomena are outside the realm of science because they are not scientifically testable. Science can provide information, but non-scientific factors decide how we use science.

Current scientific knowledge is limited to the information presently known about the natural and physical world. This is why all scientific hypotheses and models are subject to change. As we learn new information, current scientific understandings sometimes become outdated. As new information becomes available, new technologies may also arise, making old technologies obsolete.

For example, Figure 1 shows how scientists model of the atom has changed over time. As scientists conducted new experiments and gathered new evidence and data, they discarded older models of the atom in favor of revised or new models. Each newer model supported the new information that scientists had gathered.

Figure 1 A Changing Model of The Atom


11



12

Many ideas and explanations that are currently known about the natural and physical world are a result of the use of physical, mathematical, and conceptual models. Sometimes a process or idea is too large (such as the universe) or too small (such as atoms) to be studied directly, or because it is too dangerous or too expensive to be studied directly. It is important to note that models never represent a process or idea perfectly, and will change as more knowledge is gained through additional scientific research. As models become more sophisticated, they can more accurately predict the system they are concerned with.


1.Define Which of the following questions is not a scientific question?A What caused dinosaurs to become extinct?

B How is hydrochloric acid produced and contained in the stomach?

C How are atoms of nitrogen different from atoms of carbon?

D Was Isaac Newton the greatest scientist that ever lived?

2.Define The circuitry for computers was invented after scientists learned how electrons flow through certain materials, such as silicon. Computer circuitry is an example of A a prediction.

B a limitation of science.

C technology.

D a model.

3.Evaluate Your friend tells you that commercial space travel to other planets will never be possible. The technology to get people into space is too expensive, too dangerous, and too complicated. Knowing what you know about science, what would you tell your friend?

4.CompareandContrast Describe an area of study that is not science. Write three to five sentences describing why the area you chose is not science and how it could be changed to qualify as science.

TEKS

STR12_ANC_CHEM_02A.indd 12 1/18/12 3:23 PM

TEKSREVIEW

Study TipThe root words contained in hypothesis tell you the meaning of the word. Hypo- means under, and -thesis means proposition. In a way, a hypothesis is an underlying proposition for an experiment or observation.

TEKS_TXT

Know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories.

2B Scientific HypothesesTEKS 2B

What is a scientific hypothesis?Suppose you slice an apple in half. You place half the apple in the refrigerator, and set the other half on the counter and leave the room. When you return an hour later, you notice that the apple half on the counter has turned brown. You look in the refrigerator and observe that the half of the apple you placed inside is only slightly brown. You recall that a change in color of a substance can be an indicator that a chemical reaction has taken place. After observing both apple halves, you hypothesize that the chemical reactions that cause an apple to brown occur more quickly at higher temperatures.

In the example above, you developed a tentative explanation, or scientific hypothesis, for why the apple half on the counter undergoes a chemical reaction more quickly than the half in the refrigeratorchemical reactions that cause an apple to brown occur more quickly at higher temperatures. A scientific hypothesis is a tentative statement or explanation for an observation in nature. Scientific hypotheses are capable of being tested and supported, or not supported, through further observation and experimentation.

Why must a scientific hypothesis be testable?Typically, once a scientific hypothesis is stated, the next step is to develop an experiment or conduct observational research to identify evidence that either supports or does not support the hypothesis. This is because a hypothesis has no meaning unless there is observational evidence or data that supports it. For example, the scientific hypothesis, Chemical reactions that cause an apple to brown occur more quickly at higher temperatures has no meaning without an experiment or data to support it. Therefore, a scientific hypothesis must be testable. Then, information and evidence gathered can be analyzed to draw conclusions about the hypothesis. In some cases, a hypothesis will be supported by the evidence that accumulates. In other cases it will not be supported.

VocabularyHypothesis


13


Make an observation

Form a scientific hypothesis

based on the observation

Yes: Repeat experiment or gather additional

data to confirm.

Gather observational evidence and data

or develop an experiment to test the hypothesis

Is the hypothesis supported?

No: Modify or reject the hypothesis

Figure 1 Development

of a Hypothesis

What if a scientific hypothesis is supported? Suppose you design a scientific experiment to test the effect of temperature on the rate of the chemical reactions that cause an apple to brown. If you find that your experiment supports your hypothesis, are you finished? Not quite. The experiment should be repeated several times to confirm the results and to ensure that no errors have been made. Additionally, a hypothesis should be tested over a variety of conditions to confirm that all variables have been considered that might alter the results. In the best scientific tradition, it is also important to have others repeat the experiment separately to confirm the results. It is always possible that a single investigator may accidentally introduce some form of bias into the results. The more investigators who have been able to replicate the results, the less likely it will be that any bias is involved.

Hypotheses that have undergone significant testing by multiple independent scientists over a variety of conditions can be said to have durable explanatory powerthat is, they have stood up to multiple tests by many scientists. If hypotheses have been consistently supported through multiple tests, they are incorporated into a theory (if one exists) related to its given topic. At that point, additional research and tests are often devised in attempt to ensure that the revised theory is supported under all known conditions.

What if a scientific hypothesis is not supported?On the other hand, suppose the experiment did not support the hypothesis. Was the experiment then a failure? Not necessarily. A scientific investigation is never a failure, as long as it leads to information and knowledge you did not previously have. But if it is not supported, the original hypothesis itself is not very useful for making predictions or understanding observations, so it is typically modified, or in some cases, discarded. If it is modified, the cycle begins again with additional observational research and data or a new experiment to test the modified hypothesis. This cycle of development is illustrated in Figure 1.


14


Why is a scientific hypothesis only a tentative explanation? It is important to note that hypotheses are only tentative explanations and are not proven facts, regardless of how many experiments and observations support the hypothesis. This is because as new data and evidence become available, a hypothesis may need to be revised or even rejected altogether. As such, a hypothesis can never be proven true or accepted as absolute truth. It can only be supported through further observation, evidence, and experimentation.


1.Infer Which of the following is a logical next step if a scientists repeated experiments do not support his hypothesis?A Alter the experiment so that the hypothesis would be supported.

B Incorporate the scientific hypothesis into a theory.

C Modify the hypothesis and conduct a new experiment.

D End the failed investigation.

2.Identify Why can a scientific hypothesis never be proven true?A A scientific hypothesis is unreliable.

B Supporting evidence is difficult to identify.

C New information might become available that contradicts the scientific hypothesis.

D It is impossible to design an experiment that can directly test a scientific hypothesis.

3.Explain What does it mean when a hypothesis is said to have durable explanatory power? Explain.

4.Hypothesize Suppose you find that a battery-operated flashlight is not working. Write a hypothesis explaining why your flashlight might not work. Then, explain why your statement qualifies as a hypothesis.

5.Analyze Suppose you designed several experiments to test your hypothesis in Question 4 above. It turns out that none of your experiments supported your hypothesis. Was your experimentation and hypothesis a failure? Explain. Then, describe what steps you should take next.

TEKS


15


TEKSREVIEW

What does it mean that scientific theories are considered well-established and highly-reliable explanations?A scientific theory is different from the common use of the word theory. If you say that I have a theory as to why Texas A&M lost that game, you mean that you suspect that you know the reason; you have a guess. But that is very different from a scientific theory. (In this review, when we use the term theory we mean scientific theory.)

A scientific theory is a well established, highly-reliable explanation of a natural or physical phenomenon. Natural phenomena include every part of our physical environment. Natural phenomena also include the forces and energies that operate on and within our environment, such as gravity. Physical phenomena include anything that can be observed with one or more of our senses. A theory cannot be based on a nonnatural or a nonphysical cause and still be considered to be a scientific theory. Being established and highly reliable means that a theory has been repeatedly and consistently upheld by numerous, extensive scientific investigations conducted by many independent researchers. Theories are capable of unifying a broad range of observations and hypotheses.

A theory is powerful because it can be used to predict a wide variety of future events. A theory also explains how or why an event or process occurs. For example, the kinetic molecular theory explains how gas particles move. This explanation can be applied to predict the behavior of any gas under a wide variety of circumstances.

Why must a theory be capable of being tested by multiple independent researchers?Anyone could propose an explanation for events in nature. A scientific theory, however, has been tested by multiple independent researchers. This means that many scientists working separately from one another have verified the results of experiments related to the theory. This is important because individual researchers can make errors, introduce investigator bias, or use faulty methods. When a large number of independent researchers conduct investigations, the results are much more likely to be accurate.

Scientific Theories2CTEKS 2C

Know that scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations, but they may be subject to change as new areas of science and new technologies are developed.

Vocabularyscientific theory


16


A theory is a fact.

A theory is a guess.

Over time, a theory can become a law.

A theory can never be proven true. New technology, discoveries, and information can lead to its modification or rejection. In everyday language, theory refers to a guess or a suspicion. However, a scientific theory is an explanation that is both reliable and well-supported.A scientific theory cannot become a scientific law. A theory explains events, while a law does not.

Common Misconceptions About TheoriesMisconceptions Facts

How are theories subject to change as new areas of science and new technologies are developed?Although theories are thoroughly tested and evaluated, they can be changed if further scientific study supports a better explanation for the phenomenon being studied. That is, a theory is the most useful and powerful explanation of the data available at the current time. Strictly speaking, a theory is neither accurate nor inaccurate.

All theories are subject to change as new areas of science and new technologies are developed. If new evidence is identified that is not consistent with an existing theory, the theory might be revised or rejected. For example, part of Daltons atomic theory explained that atoms are indestructible and never change into other atoms. Years later, with the aid of new technology, other scientists observed changes to atoms resulting from radioactivity. They also observed nuclear fission, the process in which large atoms break apart into smaller atoms. As a result, parts of Daltons atomic theory were revised.

What is the relationship between a scientific theory and a scientific law?A common misconception is that when enough evidence is gathered, a scientific theory can become a law. In fact, scientific laws and theories are very different.

Both laws and theories are supported by large bodies of evidence gathered by multiple independent researchers. However, a theory explains a phenomenon, while a law does not offer an explanation. A scientific law is a concise statement that summarizes the results of many observations and experiments. For example, the law of conservation of energy states that energy can be changed from one form to another, but it is neither created nor destroyed. This law is well-supported by the results of many experiments. But because it does not explain how energy is conserved, it is a law instead of a theory. Some common misconceptions about theories are listed in Figure 1 below.

Study TipTo remember the power of a theory, think of the letters WEHR, which stand for Well Established, Highly Reliable.

Figure 1


17



1.Identify Which of the following best defines a scientific theory?A a well-established, highly-reliable explanation of a natural event

B a preliminary guess or idea about an event in nature

C a true statement about an event in nature

D a well-established principle that does not include an explanation

2.Explain When would an established scientific theory most likely be revised or replaced?A when one scientist argues against the theory

B when public opinion amasses against the theory

C when new evidence is gathered that does not support the theory

D when the theory is promoted to a law

3.Evaluate Suppose that you were to hear that a talented chemistry student in another class had just discovered a new theory of chemistry. Evaluate that claim based on three characteristics of a scientific theory outlined in this TEKS.

4.Describe If scientific theories cannot be proven true, why are they so powerful and useful?

5.Evaluate Your friend is describing the concept of gravity. She states that if she drops an object, it will fall to the ground every time. Most likely, does the friends description of gravity involve a hypothesis, a theory, or a law? Explain.

6.Explain How does the development of new technologies affect scien-tific theories? Explain.

TEKS


18


TEKSREVIEW

TEKS_TXTDistinguish between scientific hypotheses and scientific theories.

2DScientific Hypotheses and Scientific Theories

TEKS 2D

What is a scientific hypothesis?A scientific hypothesis is a proposed explanation for observations or an answer to a scientific question for which you can gather objective data that supports or refutes it. To create a hypothesis, a scientist asks a question about how or why a specific event occurs (or does not occur) and constructs a statement that explains the phenomenon. This statement, if testable, can be the hypothesis for an investigation.

Hypotheses are proposals. They are starting points for specific, controlled research projects. Scientists must test hypotheses. When possible, scientists test hypotheses by setting up experiments that involve independent variables, factors that change during an experiment, to determine if they affect the outcome. When a scientist changes an independent variable, he or she records any changes in the outcome, the dependent variable. Once the experiment is complete, the resulting data can be examined to determine if they support the hypothesis. If the hypothesis is not supported, the scientist must construct a new hypothesis, and the process begins again.

For example, suppose that a researcher observed that bath towels seem to lose their absorbency when they are dried using fabric softener sheets. He constructs the following hypothesis: Using fabric softener causes towels to become less absorbent.

The researcher can test this hypothesis by devising and performing an experiment. One experiment could involve two test groups of identical towels. Each test group is dried under almost identical conditions. The only difference is that a fabric softener sheet is added to the dryer for one test group only. After the towels are dried, the absorbency of each towel is measured. If the towels dried with the fabric softener sheets are less absorbent than the other towels, then the hypothesis is supported.

How can you distinguish between scientific hypotheses and scientific theories?In everyday conversation, the word theory generally means suspicion. You might say, I have a theory as to why you got a C on the chemistry test. But in science the word theory has a different meaning. A scientific theory is a well-supported explanation for observations made in many situations. So theories are much broader than hypo

Documents

STAAR Chemistry Book