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Reaction Kinetics Multiple Choice

January 1999

1.Consider the reaction:

Ca (s)+ 2H2O (l)Ca(OH)2(aq) + H2(g)

At a certain temperature, 2.50 g Ca reacts completely in 30.0 seconds.

The rate of consumption of Ca is

A. 0.00208 mol/min

. 0.0833 mol/min

C. 0.!25 mol/min". 5.00 mol/min

2.The minimum amount of energy re#uired to o$ercome the energy %arrier in a chemicalreaction is the

A. heat of reaction.. acti$ation energy.

C. &' of the reactants.

". enthalpy of the products.

3.An acti$ated comple( is a chemical species that is

A. sta%le and has lo) *'.

. sta%le and has high *'.

C. unsta%le and has lo) *'.". unsta%le and has high *'.

4.A certain reaction is a%le to proceed %y $arious mechanisms. 'ach mechanism has a

different 'aand results in a different o$erall rate. +hich of the follo)ing %est descri%es

the relationship %et)een the 'a$alues and the rates


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5.Consider the follo)ing *' diagram:

The for)ard reaction can %e descri%ed as

6.Consider the follo)ing reaction mechanism:

-n this reaction, 2 is a

A. product.

. catalyst.

C. reactant.". reaction intermediate.

April 1999

1.The slo)est of the follo)ing reactions is

A. Aga#1 Cla#1AgCl s1

. 3a#1

a#122 l1

C. 3a 2a#1 2*43a#1a3*412s1

". Cus1 2Aga#1Cu

2a#1 2Ags1


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2.The rate of a chemical reaction is e#ual to the slope of a graph )ith the a(es la%eled

3.Consider the follo)ing reaction:

C4 g1 22 g1C2g1 22 g1 heat

The diagram )hich represents the relationship %et)een rate and temperature is:

4.+hich of the follo)ing descri%es the energy of colliding particles as reacting

molecules approach each other

5. The a$erage inetic energy of colliding particles can %e increased %y

A. adding a catalyst.. increasing pressure.

C. increasing temperature.

". increasing reactant concentration.


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6. A su%stance that increases the rate of a chemical reaction and may %e reco$ered

unchanged at the end of the reaction is an1

A. product.

. catalyst.

C. acti$ated comple(.". reaction intermediate.

7. Consider the follo)ing *' diagram for a re$ersi%le reaction:

June 1999

1.+hich of the follo)ing can %e used to represent the rate of a reaction


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222 l122 l1 2 g1

+hich graph sho)s the relationship %et)een rate of consumption of 22 and time

3. Consider the follo)ing reaction:

6gs1 2Cl a#12g1 6gCl2a#1

The rate of this reaction increases )hen more magnesium is added. This change is caused

%y the

A. addition of a catalyst.

. increase in surface area.

C. change in nature of the reactants.

". increase in concentration of reactants.

4. Consider the follo)ing *' diagram:


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5.+hich graph sho)s the relationship %et)een acti$ation energy 'a)and temperature

6.A catalyst changes the rate of a reaction %y

A. changing .

. increasing the temperature.

C. decreasing the energy of the products.". pro$iding an alternate reaction mechanism.

August 1999

1.At room temperature, )hich of the follo)ing reactions is fastest

A. 2H2(g) + O2 (g)2H2O(g)B. Pb2+(aq) + 2I

-(aq)PbI2(s)

C. 4Fe(s)+ 3O2(g)2Fe2O3(s)

D. Cu(s)+ 2Ag

+

(aq)

Cu

2+

(aq) + 2Ag(s)


C4g1 22 g1C2 g1 22 g1

At a certain temperature, !.0 mol C4is consumed in 4.0 minutes.The rate of production of 2 is

A. 0.25 mol/min. 0.50 mol/min

C. 2.0 mol/min

". 8.0 mol/min

3.Consider the follo)ing reaction in a closed system:

2g1 -2g1 2HI(g)+hich of the follo)ing )ill cause the rate of the for)ard reaction to decrease

A. 2 is added.

. A catalyst is added.

C. The $olume is increased.


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". The temperature is increased.

4.The changes in *' and &', as reactant molecules approach each other, can %e

represented %y


+hich of the follo)ing descri%es this reaction

6.A chemical reaction that gi$es off energy is

A. e(othermic and is positi$e.

. e(othermic and is negati$e.

C. endothermic and is positi$e.

". endothermic and is negati$e.


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+hich of the follo)ing descri%es the system a%o$e

5.-ncreasing the temperature of a reaction increases the reaction rate %y

-. increasing fre#uency of collisions

--. increasing the inetic energy of collision---. decreasing the potential energy of collision

A. - only.. - and -- only.

C. -- and --- only.

". -, -- and ---.

6.+hat effect does a catalyst ha$e on a reaction

A. -t changes the of a reaction.

. -t increases the inetic energy of the reactants.

C. -t decreases the potential energy of the products.

". -t pro$ides a reaction mechanism )ith a lo)er acti$ation energy.

April 2000

1. At 259C, )hich of the follo)ing reactions is fastest

A. 2g1 -2g12-g1

. Aga#1 -a#1Ag-s1

C. C!2s1 2g1C2g1 2g1

". 5C242

a#1 26n4a#1 !

a#1!C2 g1 26n2a#1 82l1


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2. Consider the graph for the follo)ing reaction:

CaC3s1 2Cl a#1

CaCl2a#1 C2 g1 2l1

The a$erage rate of reaction is greatest in the time inter$al

A. 0 ! minute.. 0 2 minutes.

C. 0 3 minutes.

". 0 4 minutes.

3.+hich of the follo)ing changes )ill increase the a$erage inetic energy of reactant

molecules

A. adding a catalyst. increasing the temperature

C. increasing the surface area

". increasing the concentration

4.Consider the follo)ing potential energy diagram:

+hich of the follo)ing represents the heat of reaction, , for the for)ard reaction

A. -

. --C. ---

". -;


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5. +hen a catalyst is added to a reaction

-. the heat of reaction increases

--. a ne) mechanism is pro$ided---. the e#uili%rium constant increases

A. -- only

. - and -- only

C. -- and --- only". -, -- and ---

6.Consider the follo)ing mechanism for a reaction:/s

--. g/min---. 6/min

A. - only.

. - and -- only.C. -- and --- only.

". -, -- and ---.


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3.Consider the follo)ing reaction:n s1 2Cl a#1nCl2a#1 2g1

A graph of concentration of Cl $s time could %e represented %y

4.Consider the follo)ing e(periments, each in$ol$ing e#ual masses of 7inc and !0.0 m>

of acid:

The rate of reaction in order from fastest to slo)est is

A. - ? -- ? ---. -- ? - ? ---

C. --- ? - ? --

". --- ? -- ? -

5.+hat happens to the energy of reactant molecules as they approach one another


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C. -- and --- only.

". -, -- and ---.

4.+hich of the follo)ing is true for an acti$ated comple(

A. sta%le and has lo) *'. sta%le and has high *'

C. unsta%le and has lo) *'

". unsta%le and has high *'

5. As you increase the temperature of a reaction, the

A. rate increases and the time re#uired for the reaction increases.. rate increases and the time re#uired for the reaction decreases.

C. rate decreases and the time re#uired for the reaction increases.

". rate decreases and the time re#uired for the reaction decreases.

6.+hich of the follo)ing potential energy cur$es represents a cataly7ed endothermic

reaction in the for)ard direction

A. -

. --

C. ---". -;

January 2001

1.+hich of the follo)ing units could %e used to e(press reaction rate

A. m>/s. m>/g

C. g/m>

". m>/mol

2.Consider the reaction:

n s1 2Cl a#1nCl2a#1 2g1

The rate of production of nCl2, can %e increased %y

A. decreasing the ClD.

. increasing the temperature.C. increasing the $olume of 2.


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". decreasing the surface area of n .

3.The statement,the minimum energy needed to achieve a successful collision,defines

A. entropy.. acti$ation energy.

C. the " of reaction.

". the acti$ated comple(.

4.As an acti$ated comple( changes to products,

A. potential energy changes to inetic energy.. inetic energy changes to potential energy.

C. inetic energy changes to acti$ation energy.

". potential energy changes to acti$ation energy.

5.Consider the follo)ing *' diagram for an uncatalysed and a cataly7ed reaction:

+hich of the follo)ing descri%es the for)ard cataly7ed reaction

6.A su%stance that increases the rate of a reaction )ithout appearing in the e#uation

for the o$erall reaction is an1

A. product.

. catalyst.

C. reactant.


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". intermediate.

April 2001

1.+hich of the follo)ing reactions occurs most rapidly at standard conditions

A. 2Be s1 2g12Bes1

. Cas1 3Cs1CaC2s1 Cg1

C.


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5.+hat is the relationship %et)een the acti$ation energy and the rate of a reaction

A. +hen the acti$ation energy is high, the rate of reaction is fast.. +hen the acti$ation energy is lo), the rate of reaction is slo).

C. +hen the acti$ation energy is high, the rate of reaction is slo).

". There is no relationship %et)een acti$ation energy and rate of reaction.



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4.+hich of the follo)ing reactions is endothermic

A. C4g1 22g1C2g1 22l1 8F0.3G

. 2=a22 s1 22 l128H.0 G4=aa#1 2g1

C. Cas1 2l1Ca12a#1 I 5.2G

". Cas1 3Cs1CaC2s1 Cg1 I 44.8G

5. The follo)ing diagram sho)s reactant molecules approaching one another:

+hat is happening to the inetic energy and the potential energy

6.A proposed mechanism for a reaction is:


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A. !.5 @ !03mol/s

. 3.0 @ !03mol/s

C. .0 @!03mol/s". !.5 @!02mol/s


3Be23s1 Cg1

2Be34s1 C2g1 4G+hich of the follo)ing )ould cause the rate of the reaction to increase

A. remo$ing the Be34. decreasing the temperature

C. increasing the surface area of Be23". increasing the $olume of the reaction $essel

3.Activation energy is descri%ed as

A. the energy of the acti$ated comple(.. a point on the *' diagram )here &' I *'.

C. the unsta%le high *' structural arrangement of atoms.". the minimum *' difference %et)een the acti$ated comple( and the reactants.

4. +hat happens to the acti$ation energy and )hen a catalyst is added to a reaction

5.Consider the follo)ing potential energy diagram for a reaction:

+hat is the $alue of for this reaction

A. !20 G


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. 30 G

C. 30 G

". !20 G

6.A su%stance that is produced in one step in a reaction mechanism and consumed

in a su%se#uent step, )ithout appearing in the o$erall reaction, is an1

A. catalyst.

. product.C. reactant.

". intermediate.

January 2002

1.+hich of the follo)ing has the greatest reaction rate

A. Cs1 2g1C2g1

. 222 l122 l1 2 g1

C. 2Al s1 3CuCl2a#12AlCl3a#1 3Cus1

". =aCla#1 Ag=3a#1AgCls1 =a=3a#1

2. +hich factor e(plains )hy potassium generally reacts faster than sodium

A. surface area

. temperature

C. concentration". nature of reactants

3.+hat happens to the *' and &' of the reactants particles as the acti$ated comple( isformed

*' &' .A. increases decreases

. increases increases

C. decreases decreases

". decreases increases


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+hat are the $alues of and acti$ation energy 'a1 for the for)ard reaction


+hich of the follo)ing is a reactant in the o$erall reaction

A. Cl. Cl

C. CCl3


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". CCl3

6.Consider the follo)ing *' diagram for a cataly7ed and uncataly7ed reaction:

+hich of the follo)ing descri%es the reverse reaction

April 2002

1.+hich of the follo)ing could %e used to descri%e the rate of a reaction

A. change in time

change in mass

. change in mass

change in $olume

C. change in $olume

change in time

". change in $olume

change in mass


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222a#122l1 2g1

+hich factor e(plains )hy the a%o$e reaction speeds up in the presence of 6n2s1

A. temperature C. nature of reactants

. concentration ". presence of catalyst

3.+hat happens to the potential energy and the total energy as an acti$ated comple(

changes into products


+hich of the follo)ing descri%es the type of reaction and for the reverse reaction


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5.Consider the follo)ing diagram for a cataly7ed and uncataly7ed reaction:

+hich of the follo)ing descri%es the forward reaction


=2


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June 2002

1. +hich of the follo)ing has the lo)est rate of reaction

A. *%s1 CuCl2a#1 K Cus1 *%Cl2a#1 . Cla#1 =aa#1K 2l1 =aCla#1 C. 2


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C. 400 &G

". 500 &G

5. Consider the follo)ing reaction mechanism:


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2. +hich factor e(plains )hy coal dust is e(plosi$e

A. temperature . surface area

C. concentration

". addition of catalyst

3. As an acti$ated comple( changes into products, )hat changes occur in the chemical%onds of the acti$ated comple( and the *' of the system

onds *'

A. form increases. form decreases

C. %rea increases

". %rea decreases


+hich of the follo)ing descri%es M and the type of reaction in the for)ard direction

MG1

Type ofLeaction

A. 50 e(othermic

. 50 endothermicC. 50 e(othermic

". 50 endothermic

5. Consider the follo)ing *' diagram for a cataly7ed and uncataly7ed reaction:


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+hich of the follo)ing descri%es the for)ard reaction

Leaction Acti$ation'nergy G1

MG1

A. cataly7ed 300 !00. uncataly7ed 300 !00

C. cataly7ed 400 !00

". uncataly7ed 400 !00



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Be23s1 2Als1K Al23s1 2Bel1

-f 0.50 mol of Be is produced in !0.0sec, )hat is the rate of consumption

of Be23in mol/s

A. 5.0 O !02 mol/s

. 2.5 O !02 mol/s C. !.0 O !0! mol/s

". 5.0 mol/s

3. +hich of the follo)ing )ould result in a successful collision %et)een

reactant particles

A. particles ha$e sufficient &'

. particles con$ert all their *' into &'

C. particles are in an e(cited state and are cataly7ed ". particles ha$e sufficient &' and proper molecular orientation

4. +hich of the follo)ing %est descri%es the 'aof a fast reaction and the sta%ility of

its acti$ated comple(

'a Acti$ated

Comple(

A. small unsta%le

. small sta%le

C. large unsta%le

". large sta%le

5. o) does the addition of a catalyst increase the reaction rate of an endothermicreaction

A. -t reduces the M of the reaction. . -t increases the M of the reaction.

C. -t reduces the re#uired acti$ation energy.

". -t causes the reaction to %ecome e(othermic.



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+hat is the acti$ation energy for the reversereaction

A. 0 G

. 20 G

C. 40 G ". 0 G

April 2003

1. Consider the follo)ing reaction occurring in an open container:

CaC3s1 2Cla#1 K CaCl2a#1 2l1 C2g1

The reaction rate could %e calculated %y using )hich of the follo)ing

A. a change in ClD

. a decrease in p $alue C. a change in gas pressure

". a decrease in the mass of the system

2. +hich of the follo)ing does notaffect %oth homogeneous and heterogeneous

reaction rates

A. addition of a catalyst

. change in temperature

C. change in surface area ". change in concentration

3. o) do &' and *' change as reactant particles collide )ith each other

&' *'

A. increases increases

. increases decreases

C. decreases increases


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". decreases decreases

4. Pnder )hich of the follo)ing conditions )ill the reaction rate decrease for a

reaction )hich goes to completion

A. A catalyst is remo$ed. . *roducts are remo$ed.

C. Temperature is increased. ".


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2=g1 2g1K 2=2g1 M I !!4 G

o) could the rate of this reaction %e increased

A. Leduce the pressure.

. -ncrease the $olume.

C. Lemo$e some =2g1.". -ncrease the temperature.

3. An acti$ated comple( can %e descri%ed as

A. a particle of ma(imum &' and minimum *'.

. a sta%le particle found in a reaction mechanism.

C. an unsta%le particle that is neither reactant nor product.

". a particle )hich is first used then regenerated in a reaction mechanism.

4. +hich of the follo)ing could result in an increase in reaction rate

A. an increase in the acti$ation energy

. an increase in the reaction enthalpy

C. an increase in the fre#uency of collisions ". an increase in the potential energy of the acti$ated comple(


+hich of the follo)ing descri%es the energy $alue indicated %y -

A. heat of reaction . acti$ation energy for the re$erse reaction

C. acti$ation energy for the for)ard reaction

". potential energy of the reaction intermediate

6. Consider the follo)ing reaction mechanism and o$erall reaction:


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+hat is the catalyst in this mechanism

A. g1 . =g1 C. =2g1 ". sunlight

August 2003

1. +hich of the follo)ing reactions )ould %e slo)est at room temperature

A. ns1


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". the acti$ation energy is con$erted to inetic energy

4. Consider the follo)ing information for a re$ersi%le chemical reaction:

! for)ard acti$ation energy I 20 G

2 re$erse acti$ation energy I 30 G

+hich of the follo)ing descri%es the reaction type and enthalpy change for the for)ard reaction

Leaction Type M ;alue

A. e(othermic !0 G

. e(othermic !0 G

C. endothermic !0 G

". endothermic !0 G

5. Consider the follo)ing e(perimental results:

'(periment ! '(periment 2

Leactants Be2a#1 6n4a#1 6n4

a#1 2C24a#1

Temperature 20 40

Concentration 0.5 6 solutions !.0 6 solutions

Lates Bast


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January 2004

1. +hich of the follo)ing factors only affects the rate of heterogeneous reactions

A. nature of reactants . presence of a catalyst

C. temperature of reactants

". surface area of reactants

2. Consider the follo)ing reactions in open systems:

-. 22g1 2g1 K 22g1

--. CaC3g1K Cas1 C2g1

---. Cas1


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Leaction *' of Acti$atedComple( G1

MG1

A. cataly7ed !00 50

. uncataly7ed 300 50

C. cataly7ed 250 50". uncataly7ed !50 50


2=g1 2g1 K 2=2g1

+hy )ould this reaction pro%a%ly in$ol$e more than one step

A. There is insufficient acti$ation energy.

. This reaction has high acti$ation energy.

C. Leactions %et)een gases are typically slo). ". A successful collision %et)een more than t)o molecules is unliely.



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Unit I Multiple Choice Answers

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