chapter 5 energy and chemical change student copy1

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5.1 Physical and Chemical Changes

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CHAPTER 5 ENERGY AND CHEMICAL CHANGES

5.1 Physical and Chemical Changes5.2 Heat Change in Chemical Reactions5.3 The Reactivity Series of Metals5.4 !!lication of Reactivity Series of Metals5.5 "lectrolysis5.# "lectrical "nergy from Chemical Reactions5.$ %ight and Chemical Reactions

5.& 'nnovative "fforts in the (esign of ")*i!ment+sing Chemical Reactions as So*rces of "nergy



Physical Changes

1. The most im!ortant thing a,o*t a !hysical change is that only the

_________________________ of a s*,stance change.

2. The follo-ing are the characteristics of a !hysical change.a 't involves a ___________________________________________________

, There is ___________________________ formed.

c 't does ______________________________

d The ____________________________________________

e The changes is _____________________________________

3. The follo-ing are e/am!les of !hysical changes0

a ____________________________________________ , ____________________________________________

c ____________________________________________

d ____________________________________________

4. ,serve the follo-ing e/!eriment to *nderstand a !hysical change.

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Chemical Change

1. Chemical changes are changes -hich involve chemical reactions.

2. The characteristics of a chemical change are as follo-s.

a ne- s*,stance -hich has a ________________________________________

, This change involves ______________________ ,eca*se heat energy is *sed

___________________________

c ____________________________________

3. The follo-ing are e/am!les of chemical changes0

a ____________________________________

, ____________________________________

c ____________________________________ d ____________________________________

4. The !rod*cts of heating cannot ,e changed ,ac to the original s*,stances iron

!o-der and s*l!h*r. So this reaction is __________________________________

5. The ne- s*,stance also _______________________________________________

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E!e"imen# im 0 To st*dy chemical changesPro,lem _____________________________________________________________________

Hy!othesis _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

!!arat*s ____________________________________________________________________ _____________________________________________________________________

aria,les

6 Mani!*lated0 ________________________________________________________ 6 Res!onding0 ________________________________________________________ 6 Constant0 __________________________________________________________

Proced*re1. Set *! the a!!arat*s as sho-n in Figure 5.2.2. The co!!erll car,onate !o-der is heated.3. The change is o,served.

Res*lt1. The green solid t*rns ,lac.2. The lime-ater t*rns clo*dy.

nalysis and 'nter!retation of (ata1. 7e- s*,stances -hich fe- different com!ositions and chemical !ro!erties8 i.e. co!!er

o/ide and car,on dio/ide8 are !rod*ced. This sho-s that this reaction is a chemicalchange.

2. The e)*ation of the reaction0Co!!erll car,onate9: co!!er o/ide ; car,on dio/ide

Concl*sion ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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Ee"cises 5.1

Pa!e" $% Sec#i&n C

<ig*re 1 ,elo- sho-s a !hysical change.

a State fo*r reasons -hy the reaction in <ig*re 1 is a !hysical change. =4 mars>, St*dy the information in <ig*re 2 and e/!lain the conce!t of chemical change. ?o*r

ans-er sho*ld ,e ,ased on the follo-ing ste!s.6 Maing o,servations =1 mar>

6 'dentifying similar characteristics of <ig*res 2a and 2, =2 mars>6 Relating the characteristics of the chemical change in order to constr*ct the

conce!t of a chemical change =1 mar>6 Stating an e/am!le of chemical change and one e/am!le of non9chemical change

=1 mar>6 State the act*al conce!t of chemical change =1 mar>

________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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5.$ Hea# Change in Chemical Reac#i&ns

1. 'n a chemical reaction8 heat energy may ,e __________________________ 2. Heat energy is a,sor,ed to ________________________________ -hereas heat

energy is released -hen ___________________________________

End&#he"mic and E&#he"mic Reac#i&ns

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Ind's#"ial Chemical Reac#i&nsThe Ha(e" P"&cess )The !"&d'c#i&n of amm&nia in ind's#"y*1. The !rod*ction of ammonia thro*gh the Ha,er Process involves the reaction ,et-een

nitrogen and hydrogen gases mi/ed in the !ro!ortion of 103.

2. a The Ha,er !rocess is an ______________________________________ , 't is a reversi,le !rocess for-ard and ,ac-ard reaction.

3. 'n the Ha,er !rocess8 the follo-ing conditions m*st ,e satisfied for the o!tim*m

!rod*ction of ammonia i.e. for the for-ard reaction to occ*r.a Tem!erat*re0 't sho*ld ,e lo-8 ,*t lo- tem!erat*res can slo- do-n the reaction.

_______________________________________________________ , Press*re： high8 i.e. _______________________________________ c Catalyst： _______________________________________________

The C&n#ac# P"&cess

1. The contact !rocess is an ind*strial !rocess to !rod*ce ________________________ 2. The o!tim*m conditions to !rod*ce s*l!h*ric acid are...

a tem!erat*re： ___________________________ , !ress*re： ______________________________ c catalyst： _______________________________

3. S*l!h*ric acid is *sed...a in the !rod*ction of _____________________________

, in the !rod*ction of _____________________________ c as the ______________________________________ d as a _______________________________________

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5.+ The Reac#i,i#y Se"ies &- Me#als

Reac#i&ns &- Me#als i#h /a#e"

1. Reactive metals react -ith -ater to !rod*ce alaline sol*tions and hydrogen.

2. Potassi*m8 sodi*m and calci*m are the only three metals that can _________________

______________________

3. The follo-ing are the e)*ations for the reactions of metals -ith -ater.

A. P&#assi'm and s&di'm "eac# ac#i,ely i#h c&ld a#e"

Potassium + water potassium hydroxide + hydrogen

Sodium + water sodium hydroxide + hydrogen

0. inc can &nly "eac# i#h s#eam &" h&# a#e"

Zinc + water zinc hydroxide + hydrogen

C. N&n%"eac#i,e me#als s'ch as ________________________ d& n&# "eac# ei#he" i#h

c&ld a#e" &" h&# a#e"

Reac#i&ns &- Me#als i#h Acids

1. ery reactive metals _______________________________ react actively -ith dil*te

acids.

2. The !rod*cts of these reactions are salt and hydrogen.

3. The reaction ,et-een a reactive metal and an acid may ca*se an e/!losion.

Eam!le

8



Me#al Acid Reac#i&n Ligh#ed

s!lin#e" #es#

P"&d'c#s

magnesi*m

magnesi*m

@inc

@inc

co!!er

co!!er

Reac#i&ns &- Me#als i#h 2ygen

1. Ahen metals are heated in the !resence of o/ygen8 they -ill ,e o/idised to !rod*cemetal o/ides.

2. very reactive metal -ill ,*rn -ith a in o/ygen.3. The more reactive the metal is8 the -ill ,e.4. The reactivity of metals -hen going do-n the reactivity series of

metals.

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Metal + Ox en Metal Oxide



P&si#i&n &- Ca"(&n in #he Reac#i,i#y Se"ies &- Me#als

1. Car,on is !laced in ,et-een in the reactivity series.

2. There are t-o methods that can ,e *sed to determine the !osition of car,on in the

reactivity series.

a __________________________________________________

(*ring the reaction8 the metal -ill glo- and change in colo*r.

ll metals !laced _________________ in the reactivity series can react -ith car,on

, _____________________________________________________

(*ring the reaction8 the metal -ill glo- and ,lac s!ots -ill ,e formed on the -all of

the gas Bar.

ll metals !laced ____________ in the metal reactivity series -ill react -ith car,on

dio/ide.

Reac#i,i#y Me#al Reac#i&n i#h

a#e"

Reac#i&n i#h

dil'#e acids

Reac#i&n i#h

&ygen

6 ll react vigoro*sly

-ith a hissing

so*nd

6 Hydrogen gas is

released

6 Metal hydro/ides

are formed

6 ll react very

violently These

reactions are

e/tremely

dangero*s

,eca*se they may

ca*se e/!losions

6 Reacts readily

6 Hydrogen gas is

released

6 Calci*m hydro/ide

is formed

6 (o not react -ith

cold -ater

6 React -ith hot

-ater or steam6 Hydrogen gas is

released

6 React readily and

give off gas

,*,,les

6 Hydrogen gas isreleased

6 Metal salts are

formed

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Ee"cises 5.+1. (iagram 2 sho-s the set9*! of a!!arat*s for an e/!eriment carried o*t to st*dy the

reactivity of metals -ith o/ygen.

The e/!eriment is carried o*t three times -ith three different metals8 8 Y and D. Ta,le 2

sho-s the res*lts of the e/!eriment.

Me#al 2(se",a#i&n

E*rns ,rightly

Y Flo-s

Z E*rns less ,rightly

Table 2

a Ho- can yo* no- that a reaction has taen !laceG

=1mar>

, i Ahat is formed -hen a metal reacts -ith o/ygenG

=1mar>

ii Arite a general -ord e)*ation to sho- the reaction ,et-een a metal and

o/ygen.

=1mar>

c rrange metals X, Y and D according to their reactivity -ith o/ygen in descending

order

=1mar>

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5.3 A!!lica#i&n &- Reac#i,i#y Se"ies &- Me#als

E#"ac#i&n &- Me#al1. Metals are ____________________________________ 2. The methods of e/traction of metals de!end on _______________________________ 3. The ta,le ,elo- sho-s the methods of e/traction of certain metals.

Me#al Me#h&d &- e#"ac#i&nPotassi*m

Sodi*m

Calci*m

Magnesi*m

l*mini*m

Car,on

Dinc

'ron

Tin

%ead

Co!!erMerc*ry

Silver

Fold

E#"ac#i&n &- TinThe e/traction of tin involves t-o !rocesses8 i.e. the _____________________________ ___________________________________

Hea#ing !"&cess1. This !rocess is carried o*t to ______________________________________________ ____________________________________________ 2. (*ring this !rocess8 ____________________________________________ _________

-hereas ________________________________________________ 3. The tin ore is heated -ith coal car,on at ____________________________________

Red'c#i&n !"&cess1. Ahen heated8 the tin ore -ill ,e red*ced to tin !*re metal2. The _____________________ flo-s o*t into _________________________________

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3. _____________________________________________ is mi/ed into the ,last f*rnace __________________________________________________________

Ee"cises 5.3

(iagram $ sho-s the e/traction of tin ore at high tem!erat*re in a ,last f*rnace.

a 7ame t-o elements in P.

=2 marks>

, State one reason -hy car,on is a s*ita,le element to *se in the e/traction of tin orefrom P.

=1 mar>

c 7ame gas .

=1 mar>

d Ahat is the f*nction of limestone in this !rocessG

=1 mar>

e 7ame !rod*ct R.

=1 mar>

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5.5 Elec#"&lysis

Elec#"&ly#e4 C'""en# and Elec#"&de1. "lectrolysis is __________________________________________________________ ________________________________________________________________

2. The three main com!onents of electrolysis are...a the electrolyte 9

______________________________________________________ , a direct c*rrent so*rce 9 _______________________________________________ c t-o electrodes 9 _____________________________________________________

3. The electrodes -hich are involved in electrolysis are no-n as the

_________________ a The anode is a ______________________________________________________

, The cathode is a

_____________________________________________________ 4. ?o* have to no- that !ositively charged ions are no-n as ___________ . Cations are

____________________________________ 5. nions are __________________________ -hich are attracted to the ____________

#. "/am!le： "lectrolysis of _________________________________

a t the anode 9 ________________________________________________________ , t the cathode 9 ______________________________________________________ c "lectrodes I _____________________________________________________ d "lectrolyte 9 molten lead '' ,romide is *sed lead '' ,romide !o-der is heated *ntil

it melts ,efore the e/!eriment is started8e Aord e)*ation0 ________________________________________________

A!!lica#i&n &- Elec#"&lysis % E#"ac#i&n &- Reac#i,e Me#al1. Metals s*ch as al*mini*m8 magnesi*m and calci*m are _________________________

These metals __________________________________ ,y *sing car,on !lease refer

to the !rocess of e/traction of metals ,y *sing a ,last f*rnace.2. l*mini*m is e/tracted from its ore8 ,a*/ite al*mini*m o/ide ,y __________________

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3. The e/traction of al*mini*m is descri,ed ,elo-.

A!!lica#i&n &- Elec#"&lysis % P'"i-ica#i&n &- Me#als

1. 'm!*re metals can ,e changed into !*re metals ,y electrolysis.2. 'n this !rocess8 the im!*re metal is *sed as _____________ -hereas a !iece of the

!*re metal is *sed as _________________ 3. salt sol*tion containing the ions of the metal that is to ,e !*rified is *sed as the

A!!lica#i&n &- Elec#"&lysis一

Elec#"&!la#ing1. metal o,Bect can ,e ______________________________________ ,y electrolysis.2.Metal o,Bects made of iron r*st easily in the !resence of -ater and o/ygen.3.So8 the !rocess of electro!lating can ,e *sed to __________________________ 4.ther than that8 electro!lating can mae metal o,Bects loo more attractive and shiny.

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5. Elec#"ical Ene"gy -"&m Chemical Reac#i&ns

1. Cells can ,e classified into t-o gro*!s8 i.e：

a !rimary cells 9 .

, secondary cells 9

2. Primary cells are the

3. Secondary cells are the

Ty!e &- cell Ad,an#ages Disad,an#ages

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(ry cell

%ead9acid

acc*m*lator

laline ,attery

7icel9cadmi*m

,attery

Silver o/ide I

Merc*ry ,attery

E!e"imen# 5.

Aim6 Ma#e"ial6 A!!a"a#'s6 P"&ced'"e61. Eoth the co!!er !late and @inc !late are sand!a!ered.2. sim!le cell is set *! as sho-n in <ig*re 5.4J.

17



3. The circ*it is closed.4. The changes to the ammeter8 @inc !late and co!!er !late are o,served.,servation0

2(se",a#i&n In-e"ence

mmeter

Dinc !late

Co!!er !late

Co!!er s*l!hate

sol*tion

Disc'ssi&n61. a Dinc8 -hich is more reactive than co!!er8 acts as the _________________________

, The @inc atoms release electrons to form __________________________________ -hich move into the sol*tion.

c Th*s8 the @inc !late _________________________________ 2. The electrons flo- from the @inc !late to the co!!er thro*gh the connecting -ire. 't is

detected ,y ____________________________________________________

3. a The co!!er !late acts as ______________________________________________ , Positively charged co!!er ions in the electrolyte are _________________________

and _____________________________ from the co!!er !late to form co!!eratoms.c Co!!er atoms are ________________________________________________ d Hence8 the co!!er !late ______________________________________

4. The ,l*e colo*r of the co!!er s*l!hate sol*tion _________________________ as theco!!er ions in it __________________________________________

C&ncl'si&n6 sim!le cell converts chemical energy to electrical energy.

Ee"cise 5.

a State t-o advantages and t-o disadvantages of the lead9acid acc*m*lator.

18



=4 mars>

, st*dent fo*nd that the iron s!oons in his school la,oratory -ere r*sty."/!lain ho- he co*ld !revent the s!oons from r*sting.

?o*r e/!lanation sho*ld incl*de the follo-ing as!ects0

6 'dentify the !ro,lem =1 mar>

6 The method *sed =1 mar>

6 "/!lanation of the method =4 mars>

chapter 5 energy and chemical change student copy1

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