chemistry chapter 10 rate of reaction 1

8/13/2019 Chemistry Chapter 10 Rate of Reaction 1

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4541 CHEMISTRY Chapter 10

CHAPTER 10 : RATE OF REACTION

10.1 : Meaning of Rate of Reactio

1. Rate of reaction is a measurement of the changei !"atit#of reactatorpro$"ctin a certainrange of time.

Rate of reaction =takentime

product/ttanreacofquantityinchange

2. It is the speedat which reactants are converted into the products in a chemical reaction.

. ! rateof reaction is """". if the reaction occursfastwithin a shortperiod of time.

#. ! rateof reaction is"""". if the reaction occurs slowlywithin a longperiod of time.

$. Rate of reaction is i%er&e'#proportional with time.

Rate of reaction takentime

1

%he &horterthe time taken& the hi(herthe rate of reaction.

%he 'o(erthe time taken& the 'o)erthe rate of reaction.

'. %he change in amout of reactatorpro$"ctthat can (e measured (y )

increasing in %o'"*eofgasreleased

increasing in *a&&/cocetratioofproduct

decreasing in *a&&/cocetratioof reactant

*ormation of precipitate

changes in pH& te*perat"reore'ectrica' co$"cti%it#.

Activity 1)+

,tudy the reaction (etween 2.- g of awith e0cess of 1.- mol dm+l.

as3 4 2laq3 5 al2aq3 4 2l3 4 2g3

,ketch the graph (elow )

Chapter 10 Rate of Reaction1

%ime s3

Concentrationof

l mol dm-33

%ime s3

Concentrationof

al2mol dm-33

%ime s3

Volume of 2

gas cm33

%ime s3

Massof

ag3

+

t


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10.+ : Mea&"ri(the Rate of Reactio

1. T)oways to measure the rate of reaction )

,a- A%era(e Rate Of Reactio

!verage rate of reaction

occurtochangethefortakentime

ttanreacofamountingsindecrea//productofamountingsinincrea

/eter*iatio the averagerate of reactio fro* the (raph )

1 6 -3 cm

3

t16 - 3s

+ 6 13 cm3

t+6 t13s

(3InstantaneousRate Of Reactio Rate of Reaction at anygiventime3 )

= thegradientof the graph of the amount of reactant / product against time at any given time.


%he averagerate of reaction ithe first t1second =

%he averagerate of reaction betweent1second and t

2second =

%he rate of reaction attasecond= the gradient of tangent to the curve at the given time

= y cm3

xs

= 72+ 71

t2 + t1

%he averagerate of reaction for the

wholereaction =

7olume of

gas/ cm3

%ime/s

y

x

ta

72

71

t1

t2

7olume of gas/cm3

%ime/s

+

1

t1

t+

t


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Activity 2 )+

a3 8rite an equation for the a(ove reaction.

"""."""""""""""""""""""""""""""""

(3 9raw a la(eled diagram to show the set+up of the apparatus in the e0periment.

Chapter 10 Rate of Reaction

:raph of the volumes of car(on dio0ide gas against time

%ime/s

7olume of

car(on dio0ide

gas /cm3

1-

2-

-

#-

#- ;- 12- 1'- 2--

!n e0periment is carried out to determine the rate of reaction (etween calcium car(onate

and dilute hydrochloric acid. %he volumes of car(on dio0ide gas evolved at fi0ed

intervals are recorded.

:raph of the volumes of car(on dio0ide gas against time are shown (elow.


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c3 alculate )

i3 the averagerate of reactiofor the whole reaction.

ii3 the rate of reaction at 40 &eco$and 20 &eco$.

at #- second at ;- second

d3


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Activity )+

2- cm3of -.$ mol dm-3 l is reacted with magnesium ri((on. %he results are shown (elow.

Ti*e 3s - 1$ - #$ '- >$ ?- 1-$ 12- 1$ 1$-

o'"*e of

H+3cm3 -.- ;.$ 1'.- 22.- 2>.$ 2.- '.- ?.- #2.- ##.- #'.-

a3 9raw the graph of the volume of hydrogen gasreleased against time.

Chapter 10 Rate of Reaction$


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(3 *rom the graph& calculate )

i3 the averagerate of reaction in the first 2- seconds.

ii3 the averagerate of reaction et)ee- seconds and >$ seconds.

iii3 the rate of reaction at- seconds.

iv3 the rate of reaction at1-$ seconds.

c3 Co*parethe rate of reaction at - seconds and 1-$ seconds. 0plain why@

""""""""""""""""""""""""""""""""""""""""

""""""""""""""""""""""""""""""""""""""""

""""""""""""""""""""""""""""""""""""""""

Chapter 10 Rate of Reaction'


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10. : FACTORS THAT AFFECT THE RATE OF REACTION

1. Sie of Reactat / Tota' S"rface Area

a3 A 0periment I B

%he reaction of large piecesof calcium car(onate chips with hydrochloric acid is conducted.%he volume of gas collected in the (urette are recorded at every - seconds.

A 0periment II B

%his e0periment is repeated using small piecesof calcium car(onate chips.

%emperature& volume and concentration of l acid& and the mass of calcium car(onate are

fi0ed.

(3 hemical equation for the reaction )

a 4 2l al2 4 2 4 CO+

c3 %he graph of volume of car(on dio0ide gas against time o(tained is as shown (elow )

=p =q

0periment II

Small pieces

0periment I

Large pieces

%ime /s

7olume of 2gas / cm3

t6 t# t


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4541 CHEMISTRY Chapter 10the e0periment.

Rate of reactio at agiven time)

%hegradientof the graph at t6seconds for 0periment IIis """"""". than thegradientof

the graph for 0periment I.

%he rate of the reaction in 0periment IIis """"""". than 0periment Iat t6seconds.

%he rate of reaction of the small piecesof calcium car(onate chips is """""""" than the

rate of reaction of the large pieces.

Relationship (etween the &ieof mar(le chips and their tota' &"rface area)

small pieceshave a """""" total surface area than that of large piecesof mar(le chips of

the same mass.

%he smallerthe &ieof mar(le chips& the """"""".. the tota' &"rface areaof mar(lechips.

%he largerthe tota' &"rface areaof mar(le chips& the """"""".. the rate of reactio.

%he smallerthe &ieof mar(le chips& the """"""".. the rate of reactio.

%he ma0imum volume of car(on dio0ide gas collected for (oth e0periments are """"""".

(ecause the """"""". of the reactants are """"""".

Activity # )+

! group of students was carried out two e0periments to investigate the factor affecting the rate of a

reaction (etween Cinc and hydrochloric acid.

%a(le (elow shows information a(out the reactants used in each e0periment.

E6peri*et Reactat&

I 0cess Cinc (ra"'e&and 2$ cmD of -.$ mol dm+hydrochloric acid.

II 0cess Cinc po)$erand 2$ cmD of -.$ mol dm+hydrochloric acid.

a3 8rite the chemical equation for the reaction occur in these e0periments.

""""""""""""""""""""""""""""""""""""""".

(3 ,tate the factor that affecting the rate of the reaction of 0periment I and 0periment II.

Chapter 10 Rate of Reaction;


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4541 CHEMISTRY Chapter 10""""""""""""""""""""""""""""""""""""""".

%he graph (elow shows the result o(tained from these e0periments.

c3 alculate the average rate of reaction for 0periment I and 0periment II.

(3


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""""""""""""""""""""""""""""""""""""""".

+. Cocetratio of Reactat

a3 !n e0periment to show a reaction (etween sodium thiosulphate solution and dilute hydrochloric

acid acid is conducted.(3 %he rate of reaction is measured (y how fast yellow precipitate sulphur3 is formed.

(servation is made on the time taken for the E9F sign placed under the conical flask to disappear

from view.

%emperature& volume and concentration of the hydrochloric acid are fi0ed "tthe concentration

of sodium thiosulphate solutionis varied.

c3 hemical equation for the reaction )

Ga2,2 4 2,# Ga2,# 4 S 4 ,2 4 2

d3 %he graph of concentration of sodium thiosulphate solution against time& and the graph of

concentration against 1/time are plotted.

Chapter 10 Rate of Reaction1-

%ime s3

Cocetratioof

Ga2,

2

mol dm-33

1/time s+13

Cocetratio of

Ga2,

2

mol dm-33

Cocetratiois """""".proportional to ti*e.

8hen the concentration of Ga2,2icrea&e&& the time

taken for yellow precipitate formed that covers the H9

mark is """""""""..

%he higher the concentration of Ga2,2& the higher the

num(er of moles of Ga2,2& 3 the """""" the

num(er of particles perunit """""""""

%herefore& the """""" the frequency of

collision (etween particles.

%he """""" the frequency of effective

collisions.

%he """""" the rate of reaction.

Cocetratiois """"".proportional to 13ti*e.

A 1/timeshowsthe rate of reaction B

8hen the concentration of Ga2,2icrea&e&& the rate

of reaction is """""""""..

%he higher the concentration of Ga2,2& the """".

""" the num(er of particles perunit

""""""".


collisions (etween particles.


collisions.



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. Te*perat"re

3a ,tudy through o(servation to yellow precipitate sulphur3& the product of the reaction (etween

sodium thiosulphate solution with hydrochloric acid.3( In this reaction& thete*perat"reof the sodium thiosulphate solution is changed.

3c !ll other conditions such as volume and concentration of sodium thiosulphate solution and

hydrochloric acid is remain co&tat.

3d %ime taken for certain amount of the yellow precipitate formed and covered the H9 mark (elow

the (eaker is recorded.

3e %wo graph are o(tained )


%ime s3

Te*perat"reof

Ga2,

2

mol dm-33

1/time s+13

Te*perat"reof

Ga2,2mol dm-3

3

Te*perat"reis """""".proportional to ti*e.

8hen the temperature of Ga2,2icrea&e&& the time

taken for yellow precipitate formed that covers the H9

mark is """""""""..

%he higher the temperature of Ga2,2& the """"

the kinetic energy of,2

2+ ions and

4ions.


collision (etween particles A ,22+ ions and 4

ions B.


collision.


Te*perat"reis """"". proportional to 13ti*e.

A 1/timeshowsthe rate of reaction B

8hen the temperature of Ga2,2icrea&e&& the rate

of reaction is """""""""..

%he higher the temperature of Ga2,2& the """"

the kinetic energy of ,22+

ions and 4

ions.


collision (etween particles A ,22+ ions and 4

ions B.

%he """""" the frequency of """"".

collision



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4. Cata'#&t

J atayst is a chemical su(stance that icrea&e& the rate of reactioAchange the rate of reactionB&(ut it $oe& ot cha(e che*ica''#at the end of the reaction.

J Kositive catalyst increase the rate of reaction while negative catalyst decrease the rate of reaction.

J haracteristics of catalyst )

It does not change the !"atit# ,amount3 of the products formed.

It is unchanged chemically at the end of the reaction.

%he amount of catalyst is the same (efore and after reaction.

It is specific.

nly small amount is needed.

It could (ecome less effective when there are impurities.

J Most catalysts are transition elementsorcompounds of transition elements.

J %he presence of catalyst affects the rate of reaction.

J Luantity of catalyst also can effect the rate of reaction.

J ,tudy through )

I ) %he reaction (etween Cinc with dilute sulphuric acid

Acopper,II-sulphate& C"SO4&o'"tioas the catalystB

II) %he decomposition of hydrogen pero0ide& 22

Ausing differentquantity of manganese,I-oide& MO+as the catalystB

0periment I )

%he reaction (etween Cinc with dilute sulphuric acid AC"SO4as the catalystB

a3 hemical equation for the reaction )

n 4 2,# n,# 4 2

(3 7olume of hydrogen gas collected in a (urette are recorded at every - seconds.

c3 %his e0periment is repeated(y adding 2 cm

copperII3 sulphate solution.d3 In this reaction& mass of Cinc& volume and concentration of sulphuric acid and temperature

are remain co&tat.

e3 :raph of volume of hydrogen gas produced against time are o(tained )


o'"*eof

2gas /cm

Ti*e/s

8ithout catalyst

8ith catalyst


13/23


J *rom the graph a(ove )

%he gradient of the curve with catalyst is """""". than the curve without catalyst.

!t the end of this reaction& the total volume of 2gas in (oth reactions is the same (ecause

the """.. of Cinc and the""""""""""""". of sulphuric acid is the same.

J opperII3 sulphate as catalyst lowered the """"""..."""& Eafor the reaction.

therefore& more particles will reach the same or more than the """""""""& Eaof

the reaction.

the frequency of co''i&io(etween particles """""""""""..

the frequency of effecti%e co''i&io"""""""""""""""

the rate of reaction .."""""""""""""""..

0periment II )

a3 In this reaction& all other conditions such as volume and concentration of hydrogen

pero0ide& temperature are remain co&tat.

222 5 22 4 2

f3 :raph of volume of o0ygen gas produced againts time are o(tained )

J *rom the graph )

%he gradient of the curve using 1 &pat"'a of Mn2is """""". than using &pat"'a

of Mn2.


o'"*e of

2gas cm33

Ti*e s3

N spatula of

Mn2

1 spatula of

Mn2

!n increasein the quantity of catalyst

used will increasethe rate of

reaction.

%he quantityof catalyst does not

affect the total volume of gas

produced.

t1

t+


14/23

Optimum conditions)

%emperature ) #-- + $-- o

Kressure ) 2-- 6 #-- atm

atalyst ) Iron/ferum& Fe


!t the end of this reaction& the total volume of 2gas in (oth reactions is the same (ecause

the """"""". and """"""""""" of hydrogen pero0ide is same.

J Manganese7I3 o0ide as catalyst lowered the """""""""..."& Eafor the

decomposition of 22.

therefore& more particles will reach the same or more than the """""""""..& Ea

of the reaction.




5. Pre&&"re

J nly for reactions involving reactants ingaseousstate.

J 8hen the pressure of a reaction involving gaseous reactants3 increases& the rate of reactionincreases.

J 8hen the pressure of the gaseous reactants increases& the particles of the gaseous reactants arecompressed to occupy a smaller volume.

%hus& the num(er of gas particles per unit volume increases.




10.5 : App'icatioof factors that affect the Rate of Reactio

9aily lives )

Coo;i( of &o'i$ foo$ i &*a''er &ie

%he total surface area on a smaller cut pieces of food is larger. %he food can a(sor(ed

more heat. ence& the time taken for the food to (e cooked is lower/decrease.

Stora(e of foo$ i a refri(erator

8hen the food kept in refrigerator& the food lasts longer. %he low temperature in the

refrigerator slows down the activity of the (acteria. %he (acteria produce less to0in &the rate of decomposition of food lower.

Coo;i( i a pre&&"re coo;er

%he high pressure in pressure cooker increases the (oiling point of water to a

temperature a(ove 1-- . %he kinetic energy of the particles in the food is

increase/higher. ence time taken for the food to (e cooked is lower/decrease.

%hus the food cooked faster at a higher temperature in a pressure cooker.

In I$"&tr#)

HaerprocessO manufacture of ammonia )

G2 4 2 5 +G

Chapter 10 Rateof Reaction1#


15/23


CotactprocessO manufacture of sulphuric acid A catalyst) 7anadium73 o0ide& 72$B

O&t)a'$processO manufacture of nitric acid A catalyst) platinum& KtB

10.7 : The Co''i&io Theor#

J *or a reaction to occur& the reactants particles must collide.

J Got all collisions result in chemical reactions.

J *or a reaction to occur& the collisions must satisfy twoconditions )

i3 %he colliding particles must have the right orientation of collision.

ii3 %he colliding particles must have enough energyO i.eequalor morethan a

minimuma*o"t of eer(# known asActi%atio Eer(#< Ea

J %he collisions that lead to a chemical reaction are known as effective collisions.

10.7 : Eer(# Profi'e /ia(ra*andActi%atio Eer(#< Ea

Ea%he minimumenergy the reactant particles must possessed (efore collision (etween themcan result in a chemical reaction.

!a= %he loweractivation energy in the presence of a cata'#&t.

Activity $ )+

a3 9raw an nergy Krofile 9iagram for the reaction. n the diagram& show the )

eat of reaction&"#

!ctivation energy without a catalyst&!a

!ctivation energy with a catalyst&!a

(3 0plain the nergy Krofile 9iagram.

Chapter 10 Rate of Reaction1$

reactants

Eer(#

Krogress of reaction

Ea

products

!a

=

>H

Ea !ctivation nergy without a catalyst

!a=!ctivation nergy with a catalyst

>H eat of reactionThe energy diffence in the reactants

and in the products3

inc powder reacts with dilute hydrochloric acid. %he temperature of the mi0ture increases.


16/23


17/23


Activity ' )+

*our e0periments are carried out to study the factors that affect the rate of reaction.

%he ta(le (elow shows the details of each e0periment.

E6peri*et Reactat&Te*perat"re of HC'

3 C

I

0cess of magnesium ri((on and

$- cm hydrochloric acid 1.- mol dm6 -

II0cess of magnesium powder and

$- cm hydrochloric acid 1.- mol dm6-

III0cess of magnesium powder and

$- cm hydrochloric acid 1.- mol dm6#-

I0cess of magnesium powder and

$- cm sulphuric acid 1.- mol dm6#-

a3 8rite the chemical equation of the reaction occurred in 0periment Iand I

0periment I ) ""."""""""""""""""""""""""""""""""..

0periment I ) """""""""""""""""""""""""""""""""..

(3 alculate the ma0imum volume of gas released at room condition in )

AMolar volume of gas at room condition = 2#.- dmB

i3 0periment II

Chapter 10 Rate of Reaction1>


18/23


ii3 0periment I

c3 ,ketch the graph of the volume of gas released against time for each 0periment I& II& III and Ion

the a0es provided (elow.

d3 0plain the difference in the rate of reaction in the e0periments (elow.

Pse the ollision %heory in your e0planation.

Chapter 10 Rate of Reaction1;

Ti*e/s

o'"*eof 2gas / cm3


19/23

4541 CHEMISTRY Chapter 10i3 Iand II

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

ii3 IIand III

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

iii3 III and I

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

""""""""""""""""""""""""""""""""""""""...

Chapter 10 Rate of Reaction1?


20/23


Activity > )+

Iterpretatio of (raph.

,tudy the graphs (elow and complete the following )

Chapter 10 Rate of Reaction2-

%he (ra$ietof graph Iis """""". than graph II.

%he rate of reaction for reaction Iis """""". than reaction II.Kossi(ilities )

Reaction Iused """". siCe of reactants than reaction II.

Reaction I ) """". pieces of aO

Reaction II) """". pieces of a.

%emperature of reaction Iis """". than reaction II.

oncentration of the reactants for reaction Iis """". than reaction

II.

Kresence of catalyst )

Reaction I ) """"""""". .

Reaction II) """""""""..

*inal !"atit# ofpro$"ctfor reaction Iand IIare the &a*e.

Luantity of the reactants numer of moles3 for reaction Iand IImust (e

""""""".

Mass of the reactants used in reaction Iand IIis """""""

&umber of molesA n = M7 B of the reactants used in reaction Iand II

is """""""

Luantity of product

%ime

I

II

t1 t+

7

:R!K #.1

%he (ra$ietof graph Iand graph IIare """"""""..

%he rate of reaction for (oth reactions are """"""""..

Kossi(ilities )

,iCe of reactant for (oth reactions are """"..

%emperature for (oth reactions are """"...

oncentration of the reactants for (oth reaction are """"...

*inal !"atit# ofpro$"ctfor reaction IIis t)icethan reaction I.

Luantity of the reactants numer of moles3 for reaction Imust (e

"""". than reaction II(ecause the concentration of the reactants are

the same in (oth reactions.

!xample)

Reaction I ) 2$- cm3of l 1.- mol dm +

Reaction II) 1000cm3of l 1.- mol dm+

%ime

4

I

II

Luantity of product

:R!K #.2

t1

t+


21/23



%he (ra$ietof graph Iis """""" than graph II.

%he rate of reaction for reaction Iis """"". than reaction II.

Kossi(ilities )

,iCe of reactants for reaction Iis """". than reaction II.

Reaction I ) """". pieces of a O



Kresence of catalyst )..

Reaction I ) """"""""". "".

Reaction II) """""""""""..

oncentration of the reactants for reaction Iis """". than

reaction II


Luantity of the reactants for reaction IImust (e """ than reaction I.

Mass of the reactants used in reaction IIis """""""than

reaction I.

&umber of molesA n = M7 B of the reactants used in reaction IIis

%ime

Luantity of product

I

II

+

:R!K #.

%he (ra$ietof graph Iis """"". than graph II.

%he rate of reaction for reaction Iis """"". than reaction II.

Kossi(ilities )

,iCe of reactants for reaction Iis """". than reaction II.

Reaction I ) """". pieces of a O



Kresence of catalyst )

Reaction I ) """"""""". "".

Reaction II) """""""""""..

oncentration of the reactants for reaction Iis """". than

reaction II.


Luantity of the reactant for reaction IImust (e """ than reaction I.

Mass of the reactants used in reaction IIis """""than

reaction I.

&umber of molesA n = M7 B of the reactants used in reaction IIis

"""""than reaction I.

!xample)

Reaction I ) 2$- cm3of l 1.- mol dm+

%ime

+ II

I

t1

t+

Luantity of product

:R!K #.#


22/23


Activity ; )+

Rate of Reactio a$ Ther*oche*i&tr# ,Conclusion-

1. %he minimum energy of a reaction is """""""""".& Ea.

2. """""""""".&Eamust (e overcome in order for the reaction to take place.

. Karticles of reactants must achieve """""""""""" and with """""""""..to make the chemical reaction occurs.

#. %he use of a """""""""". reduces the Ea.

$. >H is """""""""""""""""""""""""""""""""""".

'. %he """""" the siCe of reactants& the """""" the total surface area.

>. Magnesium ri((on will react """""" with warm sulphuric acid than cool sulphuric acid.

;. %he """""" the concentration of a solution& the """""" rate of chemical reaction.

?. ! """""" is a su(stance that changes the rate of a chemical reaction. It """"""

undergo any chemical change.

1-. """"""""" is a chemical reaction in which a compound is (roken down into simplersu(stances.

Activity ? )+

omplete the ta(le (elow )

I$"&tr# proce&& Reactat& Cata'#&t

Haerproce&&



23/23


Cotact proce&&

O&t)a'$proce&&

EN/ OF CHAPTER 10

chemistry chapter 10 rate of reaction 1

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