Chapter 12 Review Questions

General Chemistry: Atoms First, 2e (McMurry and Fay) Chapter 12 The Rates and Mechanisms of Chemical Reactions

12.1 Multiple Choice Questions 1) Which term describes the measure of the increase in the concentration of a product per unit u nit time? A) activation energy ) !inetics C) reaction rate ") reaction time Ans#er$ C "iff$ 1 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions 2) (nstantaneous rate( is defined as the A) change in concentration per unit time. ) e*uation sho#ing ho# the rate depends on the concentration of each reactant. C) rate of reaction at a particular time. ") rate of reaction during a time interval. Ans#er$ C "iff$ 1 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions +) Molecular hydrogen can be made from methane gas by the reaction belo#. ,o# is the rate of disappearance of C,- related to the rate of appearance of ,2? 

/? C,- 0 g g )  ,2 0l 0l ) 3 C 0 g )  +,2 0 g g )

A)  )  C)  + ") none of these Ans#er$  "iff$ 2 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions

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-) %he burning of propane can be represented by the follo#ing e*uation$ 0 g g )  4 0 g g ) 3 + 0 g g )  - 0 g g ) %he general rate of this reaction may be e5pressed as$ A)  )  C)  ")  Ans#er$ " "iff$ 2 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions 6) %he burning of propane can be represented by the follo#ing e*uation$ 0 g g )  4 0 g g ) 3 + 0 g g )  - 0 g g ) Which of the follo#ing relationships is true? A)

/

)  4

/-

C)  +

/4

")  4

/-

Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions















7) Methanol can be produced by the follo#ing reaction$ C0 g g )  2 ,20 g g ) 3 C,+,0 g g ). ). ,o# is the rate of disappearance of hydrogen gas related to the rate of appearance of methanol? 

/?

A)  )  C)  2 ") none of these Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions 4) ,ydro*uinone8 ,C7,7,8 can be formed by the reaction #ith acetylene belo#$ 2 ,CC,  + C  ,2 3 ,C7,-,  C2 ,o# is the rate of disappearance of acetylene8 ,CC,8 related to the appearance of hydro*uinone 0,*)? 

/?

A)  )  C)  ")  Ans#er$ " "iff$ 2 %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions















9) %he reaction that occurs in a reathaly:er8 a device u sed to determine the alcohol level in a person;s bloodstream8 is given belo#. f the rate of appearance of Cr 20&-)+ is 1.2- mol.-1+ mol.927 mol mol.4>> mol mol mol mol) %he decomposition of dinitrogen pento5ide is described by the chemical e*uation 2 @260 g g ) 3 - @ 20 g g )  20 g g ) f the rate of appearance of @2 is e*ual to >.67> mol.1-> mol.29> mol














11) %he decomposition of dinitrogen pento5ide is described by the chemical e *uation 2 @260 g g ) 3 - @ 20 g g )  20 g g ) f the rate of appearance of 2 is e*ual to 2.-> mol.7>> mol mol mol mol seconds of the reaction if 1.>>  of ,22 reacts at 26BC and 1.>> atm pressure?

A) .>  1>4 M7 M6 M- M














1+) A concentrationtime study of the gas phase reaction 2 A+ 3 + A2 produced the data in the table belo#. %ime 0s) DA+E 0M) DA2E 0M) > -.>>  1> F> 1> 2.>>  1> F- +.>>  1> F2> 1.>>  1> F- -.6>  1> F+> 6.>>  1> F6 ? What is the average rate of decomposition deco mposition of A+ in the time interval 2>+> seconds? A) -.>>  1> F- M  1> F6 M>  1> F7 M>  1> F7 M -.>>  1> F> 1> 2.>>  1> F- +.>>  1> F2> 1.>>  1> F- -.6>  1> F+> 6.>>  1> F6 ? What is the average rate of formation of A2 in the time interval 2>+> seconds? A) 7.>>  1> F- M F6 M  1> F7 M>  1> F7 M
















16) A concentrationtime study of the gas phase reaction 2 A+ 3 + A2 produced the data in the table belo#. %ime 0s) DA+E 0M) DA2E 0M) > -.>>  1> F> 1> 2.>>  1> F- +.>>  1> F2> 1.>>  1> F- -.6>  1> F+> 6.>>  1> F6 ? What is the concentration of A2 after +> seconds? A) 6.>>  1> F- M ) 6.26  1> F- M C) 6.6>  1> F- M ") 7.>>  1> F- M Ans#er$  "iff$ + %opic$ %opic$ &ection 12.1 'ates of Chemical 'eactions 'eactions 17) Which statement is true for the general rate la#$ 'ate / k DAE DAEmDEn? A) t can be #ritten from the stoichiometry of the ov erall reaction. ) %he overall order of the reaction is e*ual to m times n. C) %he values for the e5ponents must be determined by e5periment. ") %he e5ponents in the rate la# must be positive integers. Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder F ED, 14) %he reaction sho#n belo# has the rate la#$ 'ate / k Dr Dr+ F EDr EDr ED,E2. F 0aq) r+ F 0aq) aq)  6 r aq)  7 ,0aq) aq) 3 + r 20aq) aq)  + ,20l 0l ) What is the overall order of reaction? A) first

















19) Gor a reaction that follo#s the general rate la#8 'ate / k DAEDE DAEDE28 #hat #ill happen to the rate of reaction if the concentration of A is increased by a factor of +.>>? %he rate #ill A) decrease by a factor of 1<.>>. ) decrease by a factor of 1<+.>>. C) increase by a factor of +.>>. ") increase by a factor of .>>. Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder Algo. ption$ algorithmic 1) Gor a reaction that follo#s the general rate la#8 'ate / k DAEDE DAEDE28 #hat #ill happen to the rate of reaction if the concentration of  is increased by a factor of 2.>>? 2.> >? %he rate #ill A) decrease by a factor of 1<-.>>. ) decrease by a factor of 1<2.>>. C) increase by a factor of 2.>>. ") increase by a factor of -.>>. Ans#er$ " "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder Algo. ption$ algorithmic 2>) %he reaction bet#een chlorine and nitric o5ide to form nitrosyl chloride is sho#n belo#. f the reaction rate doubles #hen the concentration of Cl2 is doubled and the rate *uadruples #hen the concentration of @ is doubled8 by #hat factor #ill the rate increase if both concentrations8 @ and Cl28 are doubled? Cl20 g g )  2 @0 g ) 3 2 @Cl0 g ) A) 2 ) C) 9 ") 17 Ans#er$ C

















22) Hiven the follo#ing hypothetical reaction$ 2 I0 g g )  G0 g )  H0 g g ) 3 products. f the rate la# is$ 'ate / k DIE DIE2DGE18 #hat is the order of reaction #ith respect to I? A) :ero ) first C) second ") third Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder 2+) Hiven the follo#ing hypothetical reaction$ 2 I0 g g )  G0 g )  H0 g g ) 3 products. f the rate la# is$ 'ate / k DIE DIE2DGE18 #hat is the overall order of reaction? A) :ero ) first C) second ") third Ans#er$  "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder 2-) %he decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 9>>BC 9 >>BC is independent of the concentration of ammonia at high pressures of ammonia. What is the order of the reaction #ith respect to ammonia? A) :ero ) first C) second ") third Ans#er$ A "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder 26) Cerium0J) ion reacts #ith thallium0) ion in a onestep reaction sho#n belo#$

















27) What is the overall reaction order for the reaction that has the rate la#$ 'ate / k D, D,2ED@E2? A) :ero order ) first order C) second order ") third order Ans#er$ " "iff$ 2 %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder Algo. ption$ algorithmic 24) odide and hypochlorite ion react in a*ueous solution according to the reaction belo#$   Cl 3   Cl f the concentration of , in the solution is doubled8 the rate of the reaction is halved. What is the order of the reaction #ith respect to Cl? A) 2 ) 1 C) 1 ") 2 Ans#er$  "iff$ + %opic$ %opic$ &ection 12.2 'ate a#s and 'eaction rder 29) Chlorine reacts #ith chloroform according to the reaction given belo#$ Cl2  C,Cl+ 3 CCl-  ,Cl When the initial concentration of Cl2 is doubled the reaction rate increases by b y a factor of 1.-1. What is the order of the reaction #ith respect to Cl 2? A) 1<2 ) 1 C) 1<2 ") 2 Ans#er$ C

















+>) Ksing the method of initial rates for the reaction A 3 8 if the initial concentration of A is doubled and the rate of reaction *uadruples8 #hat is the order of reaction #ith respect to A? A) :eroth ) first C) second ") fourth Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.+ "etermining a 'ate a#$ a#$ %he Method of nitial nitial 'ates +1) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ 2 ,gCl20aq) aq)  C2-20aq) aq) 3 2 Cl0aq) aq)  2 C20 g g )  ,g2Cl20 s) s) What is the rate la# for the reaction?

A) 'ate / k D,gCl D,gCl2EDC2-2E2 ) 'ate / k D,gCl D,gCl2EDC2-2E1 C) 'ate / k D,gCl D,gCl2E2DC2-2E ") 'ate / k D,gCl D,gCl2EDC2-2E2 Ans#er$ " "iff$ + %opic$ %opic$ &ection 12.+ "etermining a 'ate a#$ a#$ %he Method of nitial nitial 'ates



















+2) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ 2 ,gCl20aq) aq)  C2-20aq) aq) 3 2 Cl0aq) aq)  2 C20 g g )  ,g2Cl20 s) s) What is the value of the rate constant8 k ?

A) 1.-  1>9 14 16 1- 1


















+-) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ 0,+C)+Cr  , 3 0,+C)+C,  r  What is the value of the rate constant8 k ?

A) 9.9  1>- s1 ) -.-  1>- s1 C) 1.9  1>- s1 ") none of these Ans#er$  "iff$ + %opic$ %opic$ &ection 12.+ "etermining a 'ate a#$ a#$ %he Method of nitial nitial 'ates +6) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ r+0aq) aq)  6 r 0aq) aq)  7 ,0aq) aq) 3 + r 20aq) aq)  + ,20l 0l ). ).



















+7) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ r+0aq) aq)  6 r 0aq) aq)  7 ,0aq) aq) 3 + r 20aq) aq)  + ,20l 0l ). ). Calculate the initial rate #hen r+ is >.+> M8 r  is >.>6> M8 and , is >.16 M.

A) 7.1  1>6 M+ M2 M2 M


















+9) %he follo#ing set of data #as obtained b y the method of initial rates for the reaction$ &2920aq) aq)  + 0aq) aq) 3 2 &-20aq) aq)  +0aq) aq) What is the initial rate #hen &292 is >.16 M and  is >.16 M?

A) -.1>  1>7 M s1 ) 9.1>  1>+ M s1 C) 1.22  1>2 M s1 ") 6.->  1>2 M s1 Ans#er$  "iff$ %opic$ %opic$ &ection 12.+ "etermining a 'ate a#$ a#$ %he Method of nitial nitial 'ates +) %he firstorder decomposition of hydrogen pero5ide occurs according to the e*uation 2 ,220aq) aq) 3 2 ,20l 0l )  20 g g )



















-1) %he firstorder reaction8 &2Cl2 3 &2  Cl28 has a rate constant e*ual to 2.2>  1>6 s1 at 6+ =. What percentage of the initial amount of &2Cl2 #ill remain after 2.>> hours? A) 1.>> ) 1-.4 C) 14.1 ") 96.- Ans#er$ " "iff$ + %opic$ %opic$ &ection 12.- Girstrder 'eactions$ 'eactions$ %he ntegrated 'ate 'ate a# Algo. ption$ algorithmic -2) %he firstorder reaction8 2 @20 g g ) 3 2 @20 g g )  20 g g )8 )8 has a rate constant e*ual to >.47 s1 at 1>>> =. ,o# long #ill it ta!e for the concentration of @2 to decrease to -2 of its initial concentration? A) >.99 s ) 1.1 s C) 1.9 s ") 2.- s Ans#er$  "iff$ + %opic$ %opic$ &ection 12.- Girstrder 'eactions$ 'eactions$ %he ntegrated 'ate 'ate a# Algo. ption$ algorithmic





















--) %he follo#ing reaction is first order$ C2,7 3 2 C,+. f the rate constant is e*ual to 6.6  1>- s1 at 1>>> =8 ho# ho # long #ill it ta!e for >.+6 mol of C2,7 in a 1.>>  container to decrease to >.1> mol in the same container? A) 4.7 min ) +9 min C) 1>7 min ") 1+1 min Ans#er$  "iff$ %opic$ %opic$ &ection 12.- Girstrder 'eactions$ 'eactions$ %he ntegrated 'ate 'ate a# Algo. ption$ algorithmic -6) %he decomposition of cyclopropane8 #as observed at 6>>BC and its concentration #as monitored as a function of time. %he data set is given belo#. What is the order of the reaction





















-4) %he rate constant8 k 8 for a firstorder reaction is e*ual to -.2  1>- s1. What is the halflife for the reaction? A) 2.  1>- s ) 1.2  1>+ s C) 1.4  1>+ s ") 2.-  1>+ s Ans#er$ C "iff$ 2 %opic$ %opic$ &ection 12.6 Girstrder Girstrder 'eactions$ ,alfife Algo. ption$ algorithmic -9) Acetaldehyde decomposes at 46> =$ C,+C, 3 C  C,-. %he reaction is first order in acetaldehyde and the halflife of the reaction is found to be 6+> seconds. What is the rate





















61) Gluorine19 is an isotope used in Nositron N ositron Imission %omography %omography 0NI%) to scan the brain. f a researcher has 1.6> Og of 19G8 ho# long before it decays to 1.> ng? %he halflife of 19G is 1>.9 minutes. A) 6.2  1>2 hr ) -.7  1>2 hr C) 1 hr ") 61 hr Ans#er$ C "iff$ + %opic$ %opic$ &ection 12.6 Girstrder Girstrder 'eactions$ ,alfife 62) odine1+1 is one of the many radioactive isotopes resulting from nuclear bomb e5plosions. ,o# long #ould it ta!e for  of the iodine1+1 produced a nuclear e5plosion to disappear? %he halflife of iodine1+1 is 9.>2 days.





















bromide ion8 r 8 according to the follo#ing chemical che mical e*uation. + r0aq) aq) 3 r+0aq) aq)  2 r 0aq) aq) A plot of 1.>67 M1s1. f the initial initial concentration of r is >.9> M8 ho# long #ill it ta!e onehalf of the r ion to react? A) -.6  1>2 s ) 4.1 s C) 12 s ") 22 s Ans#er$ " "iff$ + %opic$ %opic$ &ection 12.4 &econdrder 'eactions 'eactions Algo. ption$ algorithmic





















69) ,ydrogen iodide decomposes at 9>> = via a secondorder process to produce hydrogen and iodine according to the follo#ing chemical e*uation. 2 ,0 g g ) 3 ,20 g g )  20 g g ) At 9>> = it ta!es 1-2 seconds for the initial concentration of , to decrease from 7.46  1>2 M to +.6>  1>2 M. What is the rate constant for the reaction at this temperature? A) 6.12  1>- M1s1 ) .7  1>2 M1s1 C) 1>.+ M1s1 ") 1.6  1>+ M1s1 Ans#er$  "iff$ + %opic$ %opic$ &ection 12.4 &econdrder 'eactions 'eactions Algo. ption$ algorithmic























72) f the units for rate are M s 18 #hat are the units for the rate constant8 k 8 for a :erothorder reaction? A) s1 ) M1























77) %he elementary reaction representing the formation of o:one$ is an e5ample of a RRRRRRRR reaction. A) unimolecular ) bimolecular C) termolecular























4>) A mechanism for a naturally occurring reaction that destroys o:one is$ &tep 1$ +0 g g )  ,0 g g ) 3 ,20 g g )  20 g g ) &tep 2$ ,20 g g )  0 g g ) 3 ,0 g )  20 g g ) What is the molecularity of the overall reaction?























4-) Which general rate la# belo# corresponds to an elementary bimolecular reaction? A) 'ate / k DAE DAE ) 'ate / k DAEDEDCE DAEDEDCE C) 'ate / k DAE DAE2DE























44) When the concentration of A is doubled8 the rate for the reaction$ *uadruples. When the concentration of  is doubled the rate remains the same. Which mechanism belo# is consistent #ith the e5perimental observations? A) &tep 1$ A   ⇌ " 0fast e*uilibrium) &tep 2$ A  " 3 2 C 0slo#) 0slo#)

























































































































































































































































































































































































































Chapter 12 Review Questions

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