AP ChemistryAP ChemistryChapter 14 JeopardyChapter 14 Jeopardy

Jennie L. BordersJennie L. Borders

Round 1 – Chapter 14 Round 1 – Chapter 14

Rate LawsRate Laws Half-LifeHalf-Life GraphingGraphing MechanismsMechanismsActivation Activation

EnergyEnergy SurpriseSurprise

100 100 100 100 100 100

200 200 200 200 200 200

300 300 300 300 300 300

400 400 400 400 400 400

500 500 500 500 500 500

Rate Laws 100Rate Laws 100The reaction 2ClOThe reaction 2ClO22 + 2OH + 2OH-- ClO ClO33

-- + +

ClOClO22-- + H+ H22O was studied with the O was studied with the

following results:following results:

Determine the rate law for the reaction.Determine the rate law for the reaction.

Rate = k[ClORate = k[ClO22]]22[OH[OH--]]

ExperimentExperiment [ClO[ClO22] (M)] (M) [OH[OH--] (M)] (M) Rate (M/s)Rate (M/s)

11 0.0600.060 0.0300.030 0.02480.0248

22 0.0200.020 0.0300.030 0.002760.00276

33 0.0200.020 0.0900.090 0.008280.00828

Rate Laws 200Rate Laws 200The reaction 2ClOThe reaction 2ClO22 + 2OH + 2OH-- ClO ClO33

--

+ ClO+ ClO22-- + H+ H22O was studied with the O was studied with the

following results:following results:

Calculate the rate constant.Calculate the rate constant.

229.63 M229.63 M-2-2ss-1-1

ExperimentExperiment [ClO[ClO22] (M)] (M) [OH[OH--] (M)] (M) Rate (M/s)Rate (M/s)

11 0.0600.060 0.0300.030 0.02480.0248

22 0.0200.020 0.0300.030 0.002760.00276

33 0.0200.020 0.0900.090 0.008280.00828

Rate Laws 300Rate Laws 300The reaction 2ClOThe reaction 2ClO22 + 2OH + 2OH-- ClO ClO33

-- + +

ClOClO22-- + H+ H22O was studied with the following O was studied with the following

results:results:

Calculate the rate when [ClOCalculate the rate when [ClO22] = 0.1M and ] = 0.1M and

[OH[OH--] = 0.05M.] = 0.05M.

0.115 M/s0.115 M/s

ExperimentExperiment [ClO[ClO22] (M)] (M) [OH[OH--] (M)] (M) Rate (M/s)Rate (M/s)

11 0.0600.060 0.0300.030 0.02480.0248

22 0.0200.020 0.0300.030 0.002760.00276

33 0.0200.020 0.0900.090 0.008280.00828

Rate Laws 400Rate Laws 400The following data was measured for the reaction The following data was measured for the reaction

BFBF33 + NH + NH33 F F33BNHBNH33

What is the rate law for the reaction?What is the rate law for the reaction?

Rate = k[BFRate = k[BF33][NH][NH33]]

ExperimentExperiment [BF[BF33] (M)] (M) [NH[NH33] (M)] (M) Initial Rate Initial Rate (M/s)(M/s)

11 0.2500.250 0.2500.250 0.21300.2130

22 0.2500.250 0.1250.125 0.10650.1065

33 0.2000.200 0.1000.100 0.06820.0682

44 0.3500.350 0.1000.100 0.11930.1193

55 0.1750.175 0.1000.100 0.05960.0596

Rate Laws 500Rate Laws 500The following data was measured for the reaction BFThe following data was measured for the reaction BF33 + +

NHNH33 F F33BNHBNH33

What is the rate when [BFWhat is the rate when [BF33] = 0.100M and [NH] = 0.100M and [NH33] = 0.500M?] = 0.500M?

0.1704 M/s0.1704 M/s

ExperimentExperiment [BF[BF33] (M)] (M) [NH[NH33] (M)] (M) Initial Rate Initial Rate (M/s)(M/s)

11 0.2500.250 0.2500.250 0.21300.2130

22 0.2500.250 0.1250.125 0.10650.1065

33 0.2000.200 0.1000.100 0.06820.0682

44 0.3500.350 0.1000.100 0.11930.1193

55 0.1750.175 0.1000.100 0.05960.0596

Half-Life 100Half-Life 100How do the half-lives of first-order and How do the half-lives of first-order and

second-order reactions differ?second-order reactions differ?

Since the half-lives of first-order Since the half-lives of first-order reactions are not based on initial reactions are not based on initial

concentration, then all the half-lives concentration, then all the half-lives are equal. Since the half-lives of are equal. Since the half-lives of

second-order reactions are based on second-order reactions are based on initial concentrations, then each half-initial concentrations, then each half-life is longer than the previous one.life is longer than the previous one.

Half-Life 200Half-Life 200

The gas-phase decomposition of The gas-phase decomposition of SOSO22ClCl22, SO, SO22ClCl22 SO SO22 + Cl + Cl22, is , is

first order in SOfirst order in SO22ClCl22. At 320. At 320ooC the C the

rate constant is 2.2 x 10rate constant is 2.2 x 10-5 -5 ss-1-1. . What is the half-life at this What is the half-life at this

temperature?temperature?

31,500s31,500s

Half-Life 300Half-Life 300

Molecular iodine, IMolecular iodine, I2(g)2(g), dissociates into , dissociates into

iodine atoms at 625K with a first-iodine atoms at 625K with a first-order rate constant of 0.271 sorder rate constant of 0.271 s-1-1. .

What is the half-life of the reaction?What is the half-life of the reaction?

2.56s 2.56s

Half-Life 400Half-Life 400

Molecular iodine, IMolecular iodine, I2(g)2(g), dissociates into , dissociates into

iodine atoms at 625K with a first-iodine atoms at 625K with a first-order rate constant of 0.271sorder rate constant of 0.271s-1-1. If . If you start with 0.050M Iyou start with 0.050M I22 at this at this

temperature, how much will remain temperature, how much will remain after 5.12s assuming that the iodine after 5.12s assuming that the iodine atoms do not recombine to form Iatoms do not recombine to form I22??

0.012M0.012M

Half-Life 500Half-Life 500

The first-order rate constant for the The first-order rate constant for the decomposition of Ndecomposition of N22OO55, 2N, 2N22OO55

4NO4NO22 + O + O22, at 70, at 70ooC is 6.28 x 10C is 6.28 x 10-3-3

ss-1-1. What is the half-life of N. What is the half-life of N22OO55

at 70at 70ooC?C?

110.35s110.35s

Graphing 100Graphing 100

For a second-order reaction, what For a second-order reaction, what quantity, when graphed versus quantity, when graphed versus time, will yield a straight line?time, will yield a straight line?

1/[A]1/[A]

Graphing 200Graphing 200

Consider the following data:Consider the following data:

Determine whether the reaction is first Determine whether the reaction is first order or second order.order or second order.

First OrderFirst Order

Time Time (s)(s) 00 4040 8080 120120 160160

Moles Moles of Aof A 0.1000.100 0.0670.067 0.0450.045 0.0300.030 0.0200.020

Graphing 300Graphing 300The gas-phase decomposition of NOThe gas-phase decomposition of NO22, 2NO, 2NO22

2NO + O 2NO + O22 is studied at 383 is studied at 383ooC, given C, given

the following data:the following data:

Is the reaction first order or second order Is the reaction first order or second order with respect to the concentration of NOwith respect to the concentration of NO22??

Second OrderSecond Order

Time Time (s)(s) 0.00.0 5.05.0 10.010.0 15.015.0 20.020.0

[NO[NO22] ]

(M)(M)0.1000.100 0.0170.017 0.0090.009 0.00620.0062 0.00470.0047

Graphing 400Graphing 400At 23At 23ooC and in 0.5M HCl, the following C and in 0.5M HCl, the following

data was obtained for the data was obtained for the disappearance of sucrose:disappearance of sucrose:

Is the reaction first order or second order Is the reaction first order or second order with respect to [Cwith respect to [C1212HH2222OO1111]?]?

First OrderFirst Order

Time Time (min)(min) 00 3939 8080 140140 210210

[C[C1212HH2222OO1111] ]

(M)(M)0.3160.316 0.2740.274 0.2380.238 0.1900.190 0.1460.146

Graphing 500Graphing 500

Is the following reaction first or Is the following reaction first or second order?second order?

Second OrderSecond Order

Mechanisms 100Mechanisms 100The decomposition of hydrogen peroxide is The decomposition of hydrogen peroxide is

catalyzed by iodide ion. The catalyzed catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step reaction is thought to proceed by a two-step

mechanism:mechanism:

HH22OO22 + I + I-- H H22O + IOO + IO-- (slow) (slow)

IOIO-- + H + H22OO22 H H22O + OO + O22 + I + I-- (fast) (fast)

Write the chemical equation for the overall Write the chemical equation for the overall process.process.

2H2H22OO22 2H 2H22O + OO + O22

Mechanisms 200Mechanisms 200The decomposition of hydrogen peroxide is The decomposition of hydrogen peroxide is

catalyzed by iodide ion. The catalyzed catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-reaction is thought to proceed by a two-

step mechanism:step mechanism:

HH22OO22 + I + I-- H H22O + IOO + IO-- (slow) (slow)

IOIO-- + H + H22OO22 H H22O + OO + O22 + I + I-- (fast) (fast)

Predict the rate law for the overall process.Predict the rate law for the overall process.

Rate = k[HRate = k[H22OO22]]

Mechanisms 300Mechanisms 300You find the reaction 4HBr + OYou find the reaction 4HBr + O22 2H 2H22O + 2BrO + 2Br22 to to

be first order with respect to HBr and first order be first order with respect to HBr and first order with respect to Owith respect to O22. You propose the following . You propose the following

mechanism:mechanism:

HBr + OHBr + O22 HOOBr HOOBr

HOOBr + HBr HOOBr + HBr 2HOBr 2HOBr

HOBr + HBr HOBr + HBr H H22O + BrO + Br22

Based of the rate law which step is rate Based of the rate law which step is rate determining?determining?

Rate = k[HBr][ORate = k[HBr][O22] ]

The first step is rate determining.The first step is rate determining.

Mechanisms 400Mechanisms 400The following mechanism has been The following mechanism has been

proposed for the reaction of NO with Hproposed for the reaction of NO with H22 to to form Nform N22O and HO and H22O:O:

NO + NO NO + NO N N22OO22

NN22OO22 +H +H22 N N22O + HO + H22OO

The observed rate law is rate = k[NO]The observed rate law is rate = k[NO]22[H[H22]. ]. What can we conclude about the relative What can we conclude about the relative speeds of the first and second reactions?speeds of the first and second reactions?

The second step is slow (rate The second step is slow (rate determining) and the first step is fast.determining) and the first step is fast.

Mechanisms 500Mechanisms 500Ozone in the upper atmosphere can be Ozone in the upper atmosphere can be

destroyed by the following two-step destroyed by the following two-step mechanism:mechanism:

Cl + OCl + O33 ClO + O ClO + O22

ClO + O ClO + O Cl + O Cl + O22

What is the overall reaction and list any What is the overall reaction and list any catalysts or intermediates?catalysts or intermediates?

OO33 + O + O 2O 2O22

Catalyst – ClCatalyst – ClIntermediate - ClOIntermediate - ClO

Activation Energy 100Activation Energy 100

What is the activation energy?What is the activation energy?

The difference in energy between The difference in energy between the energy to the transition state the energy to the transition state and the energy of the reactants.and the energy of the reactants.

Activation Energy 200Activation Energy 200The rate of the reactionThe rate of the reaction

CHCH33COOCCOOC22HH55 + OH + OH-- CH CH33COOCOO-- + C + C22HH55OHOH

Was measured at several temperatures, and the Was measured at several temperatures, and the following data was collected: following data was collected:

Temperature (Temperature (ooC) k(MC) k(M-1-1ss-1-1))1515 0.0521 0.05212525 0.101 0.1013535 0.184 0.1844545 0.332 0.332

Determine this data, determine EDetermine this data, determine Eaa. .

47,041.61 J/mol47,041.61 J/mol

Activation Energy 300Activation Energy 300The temperature dependence of the rate The temperature dependence of the rate

constant for the reaction is tabulated as constant for the reaction is tabulated as follows:follows:

Temperature (K)Temperature (K) k (Mk (M-1-1ss-1-1))600600 0.028 0.028650650 0.22 0.22700700 1.3 1.3750750 6.0 6.0800800 23 23

Calculate ECalculate Eaa.. 133,803.44 J/mol133,803.44 J/mol

Activation Energy 400Activation Energy 400

What part of the energy profile of a What part of the energy profile of a reaction is affected by a catalyst?reaction is affected by a catalyst?

Activation energyActivation energy

Activation Energy 500Activation Energy 500The oxidation of SOThe oxidation of SO22 to SO to SO33 is catalyzed by is catalyzed by

NONO22. The reaction proceeds as follows:. The reaction proceeds as follows:

NONO22 + SO + SO22 NO + SO NO + SO33

2NO + O2NO + O22 2NO 2NO22

Why do we consider NOWhy do we consider NO22 a catalyst and not an a catalyst and not an intermediate in this reaction?intermediate in this reaction?

NONO22 is present at the beginning and is present at the beginning and

end of the reaction. Intermediates end of the reaction. Intermediates are formed during the reaction and are formed during the reaction and

used during the reaction.used during the reaction.

Surprise 100Surprise 100

What are the 4 factors that affect the What are the 4 factors that affect the rate of a reaction?rate of a reaction?

1.1.Concentration of reactantsConcentration of reactants2. Catalysts2. Catalysts

3. State of reactants3. State of reactants4. Temperature4. Temperature

Surprise 200Surprise 200

The decomposition of NThe decomposition of N22OO55 in carbon in carbon

tetrachloride proceeds as follows: tetrachloride proceeds as follows: 2N2N22OO55 4NO 4NO22 + O + O22. The rate law is . The rate law is

first order in Nfirst order in N22OO55. At 64. At 64ooC the rate C the rate

constant is 4.82 x 10constant is 4.82 x 10-3-3ss-1-1. What . What happens to the rate when the happens to the rate when the

concentration of Nconcentration of N22OO55 is doubled? is doubled?

The rate doubles.The rate doubles.

Surprise 300Surprise 300

Consider the hypothetical reaction Consider the hypothetical reaction between A, B, and C that is first between A, B, and C that is first order in A, zero order in B, and order in A, zero order in B, and

second order in C.second order in C.

How does the rate change when [A] How does the rate change when [A] is doubled and the other reactant is doubled and the other reactant concentrations are held constant?concentrations are held constant?

The rate doubles.The rate doubles.

Surprise 400Surprise 400

Consider the hypothetical reaction Consider the hypothetical reaction between A, B, and C that is first between A, B, and C that is first order in A, zero order in B, and order in A, zero order in B, and

second order in C.second order in C.

How does the rate change when [B] How does the rate change when [B] is tripled and the other reactant is tripled and the other reactant

concentrations are held constant?concentrations are held constant?

The rate remains the same.The rate remains the same.

Surprise 500Surprise 500

Consider the hypothetical reaction Consider the hypothetical reaction between A, B, and C that is first between A, B, and C that is first order in A, zero order in B, and order in A, zero order in B, and

second order in C.second order in C.

By what factor does the rate change By what factor does the rate change when the concentrations of all when the concentrations of all

three reactants are tripled?three reactants are tripled?

The rate increases 27 fold.The rate increases 27 fold.