Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 1
Lecture 15 CH131 Summer 1Tuesday, June 18, 2019
• Complete:Effectoftemperatureonequilibrium• Predictingdirectionofchange• algebra: andso dependsonhowareactioniswritten• Disturbingequilibrium LeChatelier
Beginch 15:Acid‐baseequilibria• ThepHofwater• Weakacidsandstrongacids
Nextlecture:Purestrongacid.Pureweakacid.Partiallyneutralizedweakacid.Exactlyneutralizedweakacid.Neutralizedweakacidwithexcessbase.Practicewithtitration.
TP ThereactionN2 2H2 ⇌ 2N2H4 isendothermic.Whattemperaturerangewillresultinthegreatestamountofproducts?Hint:Sketchln vs1/ .
1. Verylow2. VeryhighT3. Theamountwillbethesameatall4. Moreinformationneeded
0%100%0%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
2
Quiz ThereactionN2O4 ⇌ 2NO2 isexothermic.Whattemperaturerangewillresultinthegreatestamountofproducts?Hint:Sketchln vs1/ .
1. Verylow2. Veryhigh3. Theamountwillbethesameatall4. Moreinformationneeded
92%8%0%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
3
Predictingdirectionofchange
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
4
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 2
TP Forthereaction2A B 2C
atacertaintimethevalueofitsreactionquotientis 7.Thismeansthevalueoftheequilibriumconstantforthereactionis…
1. 72. 73. 74. Furtherinformationneeded
0%8%25%67%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
5
TP Thevalueoftheequilibriumconstantforthegas‐phasereaction2A B Cis 10.
AtacertaintimethepartialpressuresareA,BandCare,respectively,1bar,1barand2bar.Thevalueofthereactionquotientis …
1. 22. 103. Furtherinformationneeded
67%25%8%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
6
Quiz Thevalueoftheequilibriumconstantforthegas‐phasereaction2A B Cis 10.
AtacertaintimethepartialpressuresareA,BandCare,respectively,1bar,1barand2bar.Undertheseconditions,thevalueoftheequilibriumconstantis
…
1. 22. 103. Furtherinformationneeded
15%77%8%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
7
TP Thevalueoftheequilibriumconstantforthegas‐phasereaction2A B Cis 10.
AtacertaintimethepartialpressuresareA,BandCare,respectively,0.2bar,1barand4bar.Thevalueofthereactionquotientis …
1. 0.042. 43. 104. 1005. Noneofthethese
0%0%0%
100%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
8
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 3
TP Thevalueoftheequilibriumconstantforthegas‐phasereaction2A B Cis 10.
AtacertaintimethepartialpressuresareA,BandCaresuchthatthevalueofthereactionquotientis 100.Astimepasses,thevalueofwill…
1. increase2. staythesame3. decrease
0%9%91%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
9
TP Thevalueoftheequilibriumconstantforthegas‐phasereaction2A B Cis 10.
Atacertaintimethevalueofthereactionquotientis 6.Astimepasses,thevalueofQwill…
1. increase2. staythesame3. decrease
100%0%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
10
Thevalueof andsoK dependsonhowachemicalreactioniswritten.
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
11
Q depends on how a reaction is writtenAtacertaintime,thevalueofthereactionquotientforthereaction
2A B⇌ 2C
is 1 4.0.
Atthesametime,whatwouldbethevalueofQ beforthereaction
4A 2 B⇌ 4C?
4 C 4/ A 4 B 2 12 16
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
12
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 4
Q depends on how a reaction is writtenAtacertaintime,thevalueofthereactionquotientforthereaction
2A B⇌ 2C
is 1 4.0.
Atthesametime,whatwouldbethevalueofQ beforthereaction
2C⇌ 2A B?
2 A 2 B / C 2 1/ 1 0.25
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
13
Q depends on how a reaction is writtenAtacertaintime,herearethevaluesofthereactionquotientsfortwodifferentreactions,
2A⇌ B, 5 B / A 2 2
C⇌ 3D, 6 D 3/ C 5
Atthesametime,whatwouldbethevalueofQ beforthereaction
2A C⇌ B 3D ?
7 B D 3/ A 2 C 5 6 10
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
14
TP Thevalueoftheequilibriumconstantforthereaction2A B⇌ C
is 10.Thevalueoftheequilibriumconstantforthereaction6A 3B⇌ 3C
is…
1. 102. 303. 1004. 10005. Noneoftheabove
0%23%0%77%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
15
TP Thevalueoftheequilibriumconstantforthereaction2A B⇌ C
is 10.Thevalueoftheequilibriumconstantforthereaction2C⇌ 4A 2B
is…
1. 102. 0.13. 0.014. 0.0015. Noneoftheabove
0%8%92%0%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
16
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 5
Quiz Thevalueoftheequilibriumconstantforthereaction2A⇌ Cis 1 4
andthatforthereactionD⇌ Cis 2 0.5.
Thevalueoftheequilibriumconstantforthereaction2A⇌ Dis 3 …
1. 22. 43. 64. 85. Noneoftheabove
0%0%15%85%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
17
Disturbing equilibriumEssentialidea:Asystematequilibriumrespondstoadisturbancebypartiallyoffsetting thedisturbance.
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
18
TP Thereaction3A ⇌ 2B isatequilibrium,withA e 0.10M and B e 2.0M andsoK 4000.Then0.05MofAisadded.
Atthemomentofthischange,thevalueof A willbe…
1. 0.05M2. 0.10M3. 0.15M
0%0%
100%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
19
TP Thereaction3A ⇌ 2B isatequilibrium,withA e 0.10M and B e 2.0M andsoK 4000.Then0.05MofAisadded.
Atthemomentofthischange,thevalueofQ willbe…
1. 40002. 40003. 4000
15%8%77%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
20
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 6
TP Thereaction3A ⇌ 2B isatequilibrium,withA e 0.10M and B e 2.0M andsoK 4000.Then0.05MofAisadded.
Atthemomentofthischange,thesystemwill…
1. havetoomuchreactant2. stillbeatequilibrium3. havetoomuchproduct
100%0%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
21
TP Thereaction3A ⇌ 2B isatequilibrium,withA e 0.10M and B e 2.0M andsoK 4000.Then0.05MofAisadded.
Afterthesystemisonceagainatequilibrium, A e must be…
1. 0.10M2. 0.10M3. 0.10M
0%0%
100%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
22
Quiz Thereaction3A ⇌ 2B isatequilibrium,withA e 0.10M and B e 2.0M andsoK 4000.Then0.05MofAisadded.
Afterthesystemisonceagainatequilibrium, B e must be…
1. 2.0M2. 2.0M3. 2.0M
9%0%91%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
23
Disturbing equilibriumEssentialidea:Asystematequilibriumrespondstoadisturbancebypartiallyoffsetting thedisturbance.
ThisbehavioriscalledLeChatelier’sprinciple.
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
24
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 7
Practice: Problem 14.49Lecture 15 CH131 Summer 1 2019
25
Copyright © 2019 Dan Dill [email protected]
Practice: Problem 14.52Lecture 15 CH131 Summer 1 2019
26
Copyright © 2019 Dan Dill [email protected]
Beginch15:Acid‐baseequilibriainaqueoussolutions
Lecture 15 CH131 Summer 1 2019
27
Copyright © 2019 Dan Dill [email protected]
The pH of waterWritedownthechemicalequilibriumthataccountsforthepHofwater.
H2O H2O ⇌ H3O OH
Lecture 15 CH131 Summer 1 2019
28
Copyright © 2019 Dan Dill [email protected]
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 8
The pH of waterWritedownthereactionquotientforthewaterautoionizationequilibrium.
Q H3O OH
Lecture 15 CH131 Summer 1 2019
29
Copyright © 2019 Dan Dill [email protected]
The pH of waterPurewaterat50oC ismeasuredtohaveapHof6.63.
Writedownthevalueof H3O at50oC.
H3O 10 6.63 2.34 10 7
Lecture 15 CH131 Summer 1 2019
30
Copyright © 2019 Dan Dill [email protected]
The pH of waterPurewaterat50oC ismeasuredtohaveapHof6.63.
Writedownthevalueof OH at50oC.
OH H3O 10 6.63 2.34 10 7
Lecture 15 CH131 Summer 1 2019
31
Copyright © 2019 Dan Dill [email protected]
The pH of waterPurewaterat50oC ismeasuredtohaveapHof6.63.
Writedownthevalueofthereactionquotientofthewaterautoionizationatequilibriumatat 50oC.
Qe Kw H3O OH 10 6.63 2 5.48 10 14
Lecture 15 CH131 Summer 1 2019
32
Copyright © 2019 Dan Dill [email protected]
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 9
TP Purewaterat50oC ismeasuredtohaveapHof6.63.Thismeansthatat50oC wateris…
1. acidic2. neutral3. basic
58%25%17%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
33
TP Purewaterat10oC hasH3O 5.39 10 8.
Thismeansthatat10oC wateris…
1. acidic2. neutral3. basic
0%90%10%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
34
Quiz ThepHofpurewaterisdifferentatdifferenttemperatures.Thismeansthatastemperaturechanges…
1. therelativeamountofH3O aq andOH aq inpurewaterchange
2. theacidityofpurewaterchanges3. thevalueoftheequilibriumconstantchanges4. Alloftheabove5. Noneoftheabove
23%
0%46%31%0%
Copyright © 2019 Dan Dill [email protected] 15 CH131 Summer 1 2019
36
Weakacidsandstrongacids
Lecture 15 CH131 Summer 1 2019
37
Copyright © 2019 Dan Dill [email protected]
Lecture 15 CH131 Summer 1 2019 6/18/2019 12:33 PM
Copyright © 2019 Dan Dill [email protected] 10
What is an acid?Anacidmakes H3O OH
Lecture 15 CH131 Summer 1 2019
38
Copyright © 2019 Dan Dill [email protected]
Strong acid equilibriumca 0.1M, a 1 10 , H3O 0.1M,%Yield?
Lecture 15 CH131 Summer 1 2019
39
Copyright © 2019 Dan Dill [email protected]
Weak acid equilibriumca 0.1M, a 1 10 , H3O 0.001M,%Yield?
Lecture 15 CH131 Summer 1 2019
40
Copyright © 2019 Dan Dill [email protected]
