Name Date Class

Chemical Reactionsf8:!~,~

Section 1 Chemical Formulas and Equations

A. Matter can change physically or chemically; a process that produces a chemical change is achemical .

B. A chemical is a shorthand form of what reactants are used and whatproducts are formed in a chemical reaction.

1. Some equations use or chemical to identify reactantsand products.

2. Chemical r~present chemical names of substances in a chemical

equation.

C. The mass of reactants and mass of products in a chemical reaction is always the same due to

the law of ' .

D. Chemical equations are when the number of atoms is the same on eachside of the equation.

E. is released or absorbed during a chemical reaction.. 1. When reactions release energy ( reactions), the products havebonds with less energy than those of the reactants.

u 2. When reactions absorb energy ( reactions), the reactants are~ more stable and their bonds have less energy than those of the products.Q)°2

~ 3. energy may be absorbed or released; the rate of heat release can be rapid0

~ or slow.~~ 4. The word energy can be written in a equation as a reactant or a~,~ product.Q)

.c

-E Section 2 Rates of Chemical Reactions~0

"OJ°>'5 A. Different chemical reactions take different amounts of .co

i B. energy-the amount of energy needed to start a chemical reactiont3

~ C. The rate of ' measures how quickly a reactant is disappearing or how~ quickly a product is appearing.~

~ 1. Tells how quickly the amount of a changes pe! unit of time..,>.

'Ii 2. Importance in industry: the faster a product can be made, the lower its .

.Chemical Reaction~ 31

II

Name Date Class j..

I" 1I~,ji.[~iiri]l~ [1'1 ~Tj~,j.l~~i;~~:;ii {~:;~~ii;tir~l.[~;]] 1

3. can change the rate of reaction. f' .)-,.. .

4. , the amount of a substance present in a specific volume, affectsthe rate of reaction. .,

5. affects the speed of a reaction. f.[

D. -a substance that slows down the rate of a chemical reaction J..

.,

E. -a substance that speeds up a chemical reaction; enzymes are special :protein molecules that act as catalysts in the body. :

"1"I

",

"

,.

fd

E.iii.,°2(Qc.E0

(J

:r:~~t!)(.)~.,:5'0c0°inos;'6(Q

:r:~~t!)0~'-...,00c.,a@

.,.,., .1:-..c- -o~

~0

(J

t"

32 Chemical Reactions

Name Date Class

~s~~_.1rl:rir:1iI:~~I. Sed ion 1 .Chemical Formulas~~§§~-~~IL'J~ml~l- and Equations t

Directions: Use the dues given below to complete the crossword puzzle.

1 2 3 4

5

8

9 10

12

14

15 ti

0;E-liQ)-c:'"CoE0u

:r~'"

Across Down ~1. A process that produces a chemical 1. Shorthand form for describing a :S

change (two words) chemical reaction (two words) ~6. Substances produced by a chemical 2. React~ons that require energy ~

reaction 3. ReactIons that produce energy :8 Th I 4. Neutral subatomic particle ~

.erma energy 5 Ch .. h ~.ange ill SIze, s ape, or state 'B

9. Substances on the left side of a (two words) ~chemical equation 7. The arrow in a chemical equation ~

11. These structures break in reactants reads as this. ~.c

15. Equal numbers of each kind of 10. Tells you the number of atoms of ~atom on each side of the arrow each element 8

\~~i 16. The first modern chemist .12. Is released or absorbed,13. Refers to heat. t14. The law of conservatIon of

20 Chemical Reactions

~'-,!rC Name Date Class

::= YI

Chemical Formulas and Chapter

.Equations ~~Directions: Use the terms from the word bank to fill in the blanks in front of the correct phrases below.

:- balanced endothermic products...bubbles

exothermic reactants

chemical reaction iron oxide silver sulfide

conservation of mass precipitate subscripts

1. substances that are about to take part in a chemical reaction

2. the numbers in a chemical formula that tell you the ratio of atoms in a

compound

3. the law Lavoisier devised, that says that matter is neither created nordestroyed during a reaction

4. tarnish on silver

5. what you call a chemical equation when it is written with the samenumber of each type of atom on both sides

.6. the process of changing some substances into other substances

~'- 7. a reaction that releases heat to its surroundings. Energy appears on the

.products side of the equation."s.~ 8. a sign that a gas has been producedCDCog 9. rustu

~ 10. the substances that are formed by a chemical reactione~~ ; 11. a reaction that absorbs heat. Energy appears on the left side of the&: ~ ..I- equation.'0to -:§ 12. a solid formed in a reaction by mixing two solutions>

'CCD

~ Directions: List four ways you can detect a chemical reaction.~e .~ 13" .~OJ0 14g .OJ

(:5

~ 15.&:""I 16.

-.

!8,

1;,:,,I Chemical Reactions 23.

~

)

Name Date Class

CT,

11 Chemical ~ormulas~ and Equations

Directions: Complete the following sentences by writing the correct terms in the blanks.

1. Chemical changes in a substance result in

2. Physical changes in a substance result in

3. A chemical reaction begins with substances called and ends with

substances called .

4. In a word equation, the substances on the left of the arrow are the ,

and the substances on the right side of the arrow are the .The arrow

should read as .

Directions: Answer the fol/owing questions on the lines provided5. Give two reasons why scientists prefer to use chemical equations instead of word equations.

--a. b." 6. What do the subscripts in a chemical equation tell about the equation?

0E.iiiQ)'c~ 7. Suppose you have a holiday celebration and over the evening six logs are burned in a fireplace.~ All that's left is ashes, but you know that there are just as many atoms as there were before-~ they're just in a different form. Explain how you know that.~

(!)0~Q)

.c

-5 8. The fire in the fireplace is an example of an exothermic reaction. Explain what happens in an.~ exothermic reaction."S'Cro==:r:~ 9. In one of the lab experiments you observed, water was split into hydrogen and oxygen in an~ endothermic reaction. Explain what happens in an endothermic reaction...,.00c:Q)

~ 10. If the equation below is balanced, write Yes on the line provided. If it is not balanced, write No.~QD

"~ a. 2Na + 2HzO-72NaOH + Hz()

b. 4Al + 30z-7AlzO .

t c. NH4OH + HCzH30Z-7NH4CzH30Z + HzO

d. 2Al + 6NaOH-72Na3AlO3 + 2Hz

Chemical Reactions 27

Name Date Class

Sedion 2 .Rates of Chemical;8 Reactions

Directions: Write the word true in the space next to each statement that is true. If the statement is false,rewrite the statement to make it true on the lines provided.

1. A change in state is a physical change.

2. Catalysts speed chemical reactions but are not changed by them.

.

"

3. Heat, light, or change in odor can indicate a physical change.

4. Activation energy is the minimum for reactions to start.

tc.i

.E.,;OJ

"~ 5. Cold usually speeds up reaction rates.E0

(J

~'"~u~OJ

:oS

~ 6. A low concentration of a chemical slows reaction rate.0

";;;"5'6

"'-I~'"~u

~ 7. Chemical reactions occur at the same rate no matter what the size of theuco

a reactant particles.@

~"~

~0

(J

.\

tChemical Reactions 21

Name Date Class

CT,

Rates of Chemical Reactions Chapter

H t.Directions: Use the dues to complete the puzzle.

~\' " ~

,.

!i

2I1,

!i 5:.10{I I

I,.,

1 7 84, j

-1~,.~, t:\1

'iI' .;I c

:11 :-1;'\ ~I'" C

i 10:, ~Ii i 0;::' ~

I xIi ~! 1 ~! ."1i:1 ~, I Q)

' 1 .c,~ I-

,Ii '0i:~ Across Down 5Ii! -u;

i 2. It speeds up a reaction but is not perma- 1. Amount of substance present in a certain ~..10

Ji nently changed volume ~I' ~

.i 3. It slows down a chemical reaction 4. They are broken before a chemical ~I ._1- I ~

reactIon taKes p ace "OJ-7. The minimum amount of energy needed g

i' to start any reaction (2 words) 5. Measure of how fast a reaction occurs a;1j ..(two words) ~i~ 9. By decreasmg this) you can speed up a ~! >-

:i chemical reaction (2 words) 6. These must be strong in order to cause a 8! ..chemical change to take place'! 10. Increasmg this speeds up most chemIcaliii : reactions 8. Catalysts at work in the body f

I -

: I 11. Enzymes that break down proteinsi i

24 Chemical Reactions

I!

Name Date Class

Overview.Chemical Reactions

Directions: Use the following terms to complete the concept map below. Note that one term will be used more

than once.

concentration reactant endothermic heat energy

rate of reaction catalysts temperature

Chemical reactions

can be, sta~ with a can be

(=~~~:::~:~::~~~:~::)I

and release and result in a and absorb

tuE.!Ii<U

'2~ at aE0u

I~'"t3"~<U

:S"0c:0

~ that is affected by'"I~'"t3"~..,.0"c:<Ua@

:EO00""~0u,

Chemical Reactions 19~~

Name Date Class

Key TermsChemical Reactions t

Directions: Write the letter of the corred term in Column II next to its description in Column I.

Column I Column II

1. speeds up a reaction a. rate of reaction

2. slows down a reaction b th 0 t o

.exo ermlC reac Ion3. a reaction that releases heat

dc. pro uct4. a reaction that absorbs heat

d.reactant5. a process that produces a chemical change

0 0 e. activation energy6. substance formed by a chemIcal reactIon

b h 0 b £" f. inhibitor I7. su stance t at eXIsts elore a

reaction begins g. endothermic reaction j

8. how fast a reaction occurs h. chemical reaction

9. the minimum amount of energy needed i. catalyst

to start any chemical reaction f)

Directions: Circle the terms from Column II in the word search puzzle below.QEuiOJ'c

ENDOTHERM I CREACT I ON ~E0

C L R THO E ENE R D I WWQ U H R ~:i:

TCHEMICALREACTIONS I ~(!)C.)EHESJTECKNH I L I DLCON ~OJ

.c

TPRODUCT IWEEATOTEKH ~c0

N 0 0 TIC CAT A L Y S T I HUT I :~'6

JCEKLBENLEDNLTURDFB ,:-:i:

EACT I VAT I ONENERGYN I ~~C.)

SCUEOKTWYJOOBCSELHT ~OJ0

YMDURGMNVOTPU UUPSSO ~a

ORATEOFREACT I ONL I PR @~aD

A F N 0 K C E A G N D T C W MEN S N .~0u

EXOTHERM I CREACT I aNY

f c

~~22 Chemical Reactions /i1;;~~

Name Class Date

CHAPTERI

;' -",' ~CTIVITY \I Chemical Reactions ~

Balancing Equations

1. Na + O2 ~ Na20

2. H2 + O2 ~ H2O

3. Na2S0. + CaCl2 ~ Caso. + NaCI

4. Al20s ~ Al + O2

~ :~. -~ 5. N 2 + H2 ~ NHs

~6. Fe + H2O ~ FesO. + H2

'1. p. + O2 ~ P.01O

8. C2H6 + O2 ~ CO2 + H2O

9. SiCI. ~ Si + C12

10. C + H2 ~ CH4

~ ' )

@ Prentice-Hall, Inc. 7

-2-

6. NaOH + H2C03 => Na2C03 + H2O

7. KOH + HBr => KBr + H2O

8. AI + S8 => AI2S3

9. Na + O2 => Na20

10. H3P04 + Mg(0H)2 => M~(P04h + H2O

Name

Balancing Equations .

Balance the following chemical equations, showing your work in thespaces provided. (Some may already be balanced.) REMEMBER: Onlycoefficients may be added or changed. Never chan1!e subscripts!!

1. H2 + O2 => H2O

2. H~04 + KOH => K~04 + H2O

3. K + B203 => K2O + B

4. HCI + NaOH => NaCI + H2O

;

5. Na + NaN03 => Na20 + N2

Name

Balancing Equations II

Balance the following chemical equations, showing your work in thespaces provided (Some may already be balanced) REMEMBER: Onlycoefficients may be added or changed Never chanJ!e subscripts!!

1. C3Hg + 02 => CO2 + H2O

2. NH3 + HCI => ~CI

3. C2~ + O2 => CO2 + H2O

4. NH3 + O2 => N2 + H2O

5. Fe82 + O2 => Fe203 + 802

-2-

6. C~ + O2 => CO2 + H2O

7. N2 + H2 => NH3

8. C6~ + O2 => CO2 + H2O

9. Al(OH)3 + H2C03 => AI2(C03)3 + H2O

10. Li + AICI3 => LiCI + AI

I Balancing Equations Answers I

~I 2H2+02=>2H20 I

~I H3P04+3KOH=:~P04+3H20 I

~I 6K+B203=>3~0+2B I

~I HCI +NaOH=> NaCI + H2O I

~I 10Na+2NaN03=>6Na20+N2 I

~I 4C+SS=>4CS2 I

~I 2 Na+02=>Na202 I

~I 2N2+502=>2N20S I

~ I 2 H3PO 4 + 3 Mg(0H)2 => Mg3(P0 4)2 + 6 H2

~ I 2 NaOH + H2C03 => Na2C03 + 2 H2O I

01 KOH + HBr=> KBr + H2O I

01 ~+02=>H202 I

01 4Na+02=>2Na20 I

01 2 AI(OH)3 + 3 H2C03 => AI2(C03)3 + 6 H2 I

01 16AI+3SS=>8AI2S3 I

01 6Cs+N2=>2Cs3N I

01 Mg+CI2=> MgCI2 I

01 10Rb+ 2 RbN03 =>6 Rb20 +N2 I

01 2C6H6+1502=>12C02+6H20 I

http://www.chemistrycoach.corn/baleqans.htm 2/16/2006

Name Date Class

Chemical Reactions;".If

,~

Part A. Vocabulary Review

Directions: Match the items in Column II with the definitions in Column I, Write the letter of the correct term in

the blank at the left.

Column I Column II

1. process that produces chemical change a. activation energy

2. substance that slows down a chemical reaction b. catalyst

3. reaction in which heat energy is absorbed c. chemical reaction

4. substance that exists before a chemical reaction begins d. endothermic reaction

5. minimum amount of energy needed in order for a e. exo"iherrnic reactionreaction to begin

f. inhibitor6. substance formed by a chemical reaction

, g. product7. substance that speeds up a chemIcal reaction

8 " h ' h h ' I d h. rate of reaction.reaction III w IC eat energy IS re ease

, i. reactant.9. a measure o~ how fast a reaction occurs

Part B. Concept Review

~ Directions: In the space before each equation, write a B if the equation is balanced or a U if the equation is unbalanced.ojQ)

.~ 1. MgCO3 + 2HCI~MgCI2 + H2CO3E0

~ 2. 2H2+ 02~H2O:i:~~ 3. CaCI2~2Ca +C12"~~ 4. Zn + 2HCI~ZnCI2 + H2

~ Directions: In the space at the left, write the letter of the answer that best completes the statement or answersco

~ the question.~

~ 5. Evidence that a chemical change has occurred includes a .~ a. change in state c. change in shape~ b. change in size d. change in color0"co

a 6. An oven's high temperature speeds up chemical reactions because heat ..~ a. lowers the activation energy.~ b. activates catalysts8 c. makes more molecules collide with each other

d. reduces the Particle size of the reactants.Chemical Reactions 35

Name Date Class

~;,~' !l.~1 r~~~'J~lf!~ ~~~:.~.~iiJ.~,{:;;;i~~

7. You can slow down the rate of a reaction by .f'a. increasing concentration c. decreasing particle sizeb. increasing temperature d. adding an inhibitor

8. Which of the following is not an example of an exothermic reaction? ,a. the splitting of water into hydrogen and oxygen :

b. fireworks explodingc. fish that emit lightd. propane and oxygen changing into carbon dioxide and water I

9. In an exothermic reaction, heat is .a. absorbed c. released 1b. conserved d. destroyed

10. Activation energy is necessary for a chemical reaction to occur because .a. breaking bonds requires energyb. some reactions happen at cold temperaturesc. all reactions are endothermicd. forming bonds requires energy

11. A chemical that keeps food from spoiling is an example of .a. a catalyst c. a reactantb. an enzyme d. an inhibitor

!12. Presence of a catalyst .,:I;

a. stops a reaction c. slows down a reaction If;b. raises the activation energy needed d. reduces the activation energy needed

13. To check whether an equation is balanced, .~-a. add the number of reactants to the number of products ,~

rob. make sure the masses of the reactants and products are the same ~c. count the number of each type of atom on each side ~d. check to see if the reaction is endothermic or exothermic ~

~~

14. Energy is usually only shown with the products in an equation for. ~a. an endothermic reaction c. an exothermic reaction :::

0

b. a synthesis reaction d. activation energy ,§In'>

15. The only balanced equation shown is .~a. H2+ 02~H2O c. Ag + H2S~Ag2S + H2 ~-b. AgNO3 + NaI~AgI + NaNO3 d. Na + CI2~NaCI J

0~'U;-00c:OJa@

~.~

~0

.u

~

36 Chemical Reactions

Name Date Class

Chemical ReactionsI';':,...

I. Testing ConceptsDirections: In the blank at the left, write the letter of the choice that best completes each statement.

1. The presence of a(n) speeds up a reaction.a. reactant b. catalyst c. product d. inhibitor

2. Heat is absorbed during reactions.a. activation b. endothermic c. enzyme d. exothermic

3. Substances formed during chemical reactions are .a. catalysts b. oxides c. reactants d. products

4. A is a process in which new substances are formed.a. chemical reaction c. reactantb. catalyst d. subscript

5. The melting of ice is an example of a(n) .a. chemical change c. exothermic reactionb. endothermic reaction d. physical change

6. For a chemical reaction to begin, is needed.a. combustion c. activation energy

.b. a catalyst d. a spark

7. The rate of reaction in a chemical change can be measured by how fast a(n)

appears.~ a. reactant c. exotherm.~ b. activator d. productto0-

~ 8. Adding an inhibitor tends to a reaction.!f: a. slow down c. speed up~~ b. stop d. reverseco~.s 9. Chemical reactions usually speed up at temperatures.~ a. Celsius c. higher:§ b. lower d. absolute>

'6

~ 10. Reactants have their highest concentrations a chemical change takes place.J a. after c. both A and Bto

<3 b. before d. neither A nor B~'-Q)g 11. A higher concentration of reactant will speed up a chemical reaction because there13 will be more between the reactantParticles.@.EO a. combustion c. bondsco.~ b. space d. collisions0u

12. Catalysts the actiyation energy needed to start a chemical reaction.'..,~ a. ~nhibit c. reduce., b. Increase d. balance

Chemical Reactions 37" '"

Name Date Class

1:~~Ji~ii~~llt~~~i. ~~~.~.~!.il.'c':~~~~~]13. To check that an equation is balanced, count the number of on each side of fjZ!

the equation.a. ions c. atoms of each typeb. molecules d. types of elements

14. The is a measure of how fast a reaction proceeds. I .a. rate of reaction c. activation energyb. catalyst effect d. concentration

15. The size of the reactant particles can affect the of a reaction. .

a. temperature c. concentrationb. product d. rate

Directions: Correctly complete each sentence by underlining the best of the three choices in parentheses.

16. The burning of paper is an example of a(n) (physical change, chemical change,endothermic reaction).

17. The molecule H2C2H3O2 has (four, eleven, nine) atoms.

18. In an endothermic reaction, (inhibitor, energy, catalyst) is absorbed.

19. A catalyst speeds up a reaction by reducing (concentration, activation energy, temperature).

20. Energy is released in a(n) (exothermic, endothermic, reverse) reaction.

II. Understanding Concepts tSkill: Comparing and Contrasting g1. Compare and contrast the effect of a catalyst on a chemical reaction with that of an inhibitor. ~

"2'"Co

E0r- c.>

:I:~'"<:5Skill: Observing and Inferring ~.c

Directions: Answer the following questions using complete sentences. Remember that iron reacts with -5atmospheric oxygen to produce iron oxide, or rust. :~

>2. One sample of iron is left outdoors, while a second identical sample is kept inside in a dry ~

place. After a period of time, you observe more rust on the sample left outdoors than on the ~sample kept inside. What can you infer from this observation? ~

"~"-

OJ0"I:OJa@

3. Two samples of iron are placed together outdoors. One sample is painted, the other is not. ~What would you expect the conditions of the two samples to be like after a period of time? ~Explain.

t38 Chemical Reactions

Name Date Class

l!r~~!L~~j Ir~~L~ :~~~~liJil.'clj[~i~

t Skill: Interpreting Scientific Illustrations

Directions: Study the graph below. Then answer the questions on the lines provided.

I/

Catalyst /Intri)..duced J

"", /c~ /Q=f ,

; 1~ /

/V

""'-

v"'"V "

L

t 4. What does the :aPh illustrate?

"(.).5

"~ Directions: Use the illustration showing the same reaadnts under different conditions to answer the followingto

~ questions.u

I~~"(.)~.,oS

'0c0"00"5'6

co. reactants reactants

i 5. What are the different conditions shown?~(.)~..,.0(.)c.,a

@

~.~

~8 6. Under which conditions does the reaction proceed at a faster rate? Why?

.t~ ,

.\"

Chemical Reactions 39

Name Date Class

1,;r-~!ii~.Ilt:j~ii [I=.=,jl.i~i~c{=:!~~~

III. Applying Concepts tDirections: Study each chemical equation. If the equation is balanced, write "balanced" in the space provided.If it is not balanced, write "unbalanced" and explain why it is not.

Balanced or Unbalanced1. Zn + HCl~ZnClz + Hz )

,2. HzCO3~HzO + COz

3. Fe + 30z~2FezO3

4. BaClz + NazSO4~BaSO4 +2NaCI

IV. Writing SkillsDirections: Answer the following questions using complete sentences.

1. What kind of reaction is displayed by a burning match? What role does rubbing the matchhead on a rough surface have in the reaction? t

I 0E.

2. How do you know that the spoiling of food involves a chemical reaction? What purpose does .~'"refrigerating food serve? ~

0u

I~ , 3

~t!Ju~Q)

:S'5c

3. Why do wood splinters burn faster than the log from which they came? :~'6'"I3~t!Ju~

, Q)0ucQ)

4. What are enzymes? List two ways that your body uses enzymes. ~~~'c

.~0u

.

t40 Chemical Reactions

Name .Class Date

CHAPTER

-",; ACTIVITY (i;){ 1. .Chemical Reactions ~

Identifying and Balancing Chemical Equations

Identify each of the equations below as synthesis, decomposition, single replacement,or double replacement.

1. HgO ~ Hg + O2

2. NaCI + AgNOg ~ NaNOg + AgCI

3. Mg + HCI ~ MgCl2 + H2

4. Zn + H2SO 4 ~ ZnS04 + H2

5. NaOH + HCI ~ NaCI + H2O

6. AI2(S04)g + Ca(OH)2 ~ AI(OH)g + CaS04 ..

7. H2 + O2 ~ H2O

8. Cl2 + NaBr ~ NaCI + Br2

9. Zn + CUS04 ~ ZnS04 + Cu

" 10. KCIOg ~ KCI + O2.."

\:::! 11. H2O + Fe ~ Fe20g + H2/'

12. Ca(OH)2 + HNOg ~ Ca(NOg)2 + H2O

13. Na20 + CO2 ~ Na2COg

14. H2 + N2 ~ NHs

Balance the following chemical equations.

15. HgO + Cl2 ~ HgCI + O2

16.. Na + Br2 ~ NaBr

17. KCIOg ~ KCI + O2

18. Ca(OH)2 + HNOg ~ Ca(NOg)2 + H2O

19. Al2Os ~ Al + O2

20. CuCl2 + H2S ~ CuS + HCI

21. Cl2 + NaBr ~ NaCI + Br2

22. NaOH + HCI ~ NaCI + H2O

23. Na20 + CO2 ~ Na2COg

" 24. H2O + Fe ~ Fe20g + H2, _J

@ Prentice-Hall, Inc. 9