Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:12 PM
Copyright © 2016 Dan Dill [email protected]
TP Identifythecorrectstatementabouttheredoxreaction
Zn2 aq Cu s ⇌Cu2 aq Zn s .
17%
17%
17%
17%
17%
17%
1.
2.
3.
4.
5.
6.
Zn2
Cu s
Zn2
Cu s
Zn2
Cu s
Lecture 21 CH101 A1 (MWF 9 am)
Wednesday, October 26, 2016
• Complete:Acid‐basereactions
• Oxidation‐reductionequations
• ComplexationasLewisacid‐basereaction
aq isthereducingagentbecauseitgainselectrons
isthereducingagentbecauseitgainselectrons
aq isthereducingagentbecauseitloseselectrons
isthereducingagentbecauseitloseselectrons
aq isthereducingagentbecauseitisreduced
isthereducingagentbecauseitisreduced
Nextlecture: Beginch7:ChemicalReactionsandEnergyFlows
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Acid or base?
Base strength
IsHCO3 andacidorabase?
Weakbasesareweakelectrolytes:Theyreactonlytoasmallextentwithwater
HO:H aq :NH2CH2CH3 aq ⇄ H:NH2CH2CH3 aq HO: aq
Onlyalittlereaction 100%theoreticalyield
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Copyright © 2016 Dan Dill [email protected]
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:12 PM
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Base strength
Redox reactions: Competition for e−
Strongbasesarestrongelectrolytes:Theyreactnearlycompletelywithwater
Na:OH s  Na aq HO: aq
Nearlycompletereaction ~100%theoreticalyield
HO: aq isastrongprotonacceptor
Oxidation‐reductionreactionsareacompetitionforelectrons
NotethatNaOH s isaspecialcase:ThereisnocompetitionforH ,only
hydrationofOH .
Speciesthatgivesupe 
is oxidized
Itmakespossiblereduction
andsoiscalledthereducingagent
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Redox reactions: Competition for
Copyright © 2016 Dan Dill [email protected]
e−
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Redox reactions: Competition for
Copyright © 2016 Dan Dill [email protected]
e−
Oxidation‐reductionreactionsareacompetitionforelectrons
Redoxreactionsareacompetitionforelectrons
2Ag aq Cu s ⇌2Ag s Cu2 aq
Speciesthatacceptse 
isreduced 
Itmakespossibleoxidation
andsoiscalledtheoxidizingagent
Oxidation
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Copyright © 2016 Dan Dill [email protected]
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:12 PM
Copyright © 2016 Dan Dill [email protected]
Redox reactions: Competition for e−
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Getting balanced redox (full) reaction
2Ag aq Cu s ⇌2Ag s Cu2 aq
Redoxreactionsareacompetitionforelectrons
2Ag aq Cu s ⇌2Ag s Cu2 aq
First,getthebalancedhalf‐reactions
Reduction
Then,combinethehalf‐reactionssothattheelectronsreleased intheoxidation
areexactlyconsumed inthereduction…
13
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
TP Identifythecorrectstatementabouttheredoxreaction
Zn2 aq Cu s ⇌Cu2 aq Zn s .
17%
17%
17%
17%
17%
17%
1.
2.
3.
4.
5.
6.
Zn2
Cu s
Zn2
Cu s
Zn2
Cu s
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Lewis alternative definition of acids and bases
Brønsted‐Lowryacidisthesourceifaproton
HCl aq H2O l  H3O aq Cl aq
Brønsted‐Lowrybaseacceptsaproton
NH4 aq OH aq  H2O aq NH3 aq
aq isthereducingagentbecauseitgainselectrons
isthereducingagentbecauseitgainselectrons
aq isthereducingagentbecauseitloseselectrons
isthereducingagentbecauseitloseselectrons
aq isthereducingagentbecauseitisreduced
isthereducingagentbecauseitisreduced
Lewisacid“accepts”apairofelectronstoformacovalentbond
Lewisbasehasapairofelectronstoformacovalentbond
Co3 aq :NH3 aq  Co :NH3 3 aq
Resultisacid‐baseadduct
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Copyright © 2016 Dan Dill [email protected]
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:12 PM
Copyright © 2016 Dan Dill [email protected]
Complexation as Lewis acid-base reaction
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Complexation as Lewis acid-base reaction
lonepairsource Lewisbaseorligand.
lonepairsource Lewisbaseorligand.
whatbonds tolonepair Lewisacid.
whatbonds tolonepair Lewisacid.
productofacid‐basereaction acid‐baseadduct.
productofacid‐basereaction acid‐baseadduct.
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Complexation as Lewis acid-base reaction
Complexation as Lewis acid-base reaction
lonepairsource Lewisbaseorligand.
lonepairsource Lewisbaseorligand.
whatbonds tolonepair Lewisacid.
whatbonds tolonepair Lewisacid.
productofacid‐basereaction acid‐baseadduct.
productofacid‐basereaction acid‐baseadduct.
Be2 aq
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Copyright © 2016 Dan Dill [email protected]
4H2O l  Be H2O
4
2
aq
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
2/6/2017 1:12 PM
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Complexation as Lewis acid-base reaction
Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
Copyright © 2016 Dan Dill [email protected]
Complexes have characteristic colors
lonepairsource Lewisbaseorligand.
whatbonds tolonepair Lewisacid.
productofacid‐basereaction acid‐baseadduct.
Cu2 aq
4NH3 aq  Cu NH3
4
2
aq
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Lecture 21 CH101 A1 (MWF 9 am) Fall 2016
35
Copyright © 2016 Dan Dill [email protected]
TP Inthereaction
Cu :OH2 6 2 aq 4:Cl aq 2:NH3 aq 
Cu :NH3 2:Cl4 2 aq 6:OH2 l
thenumberofLewisacidsis…
17%
17%
17%
17%
17%
17%
1.
2.
3.
4.
5.
6.
0
1
2
3
4
5
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Copyright © 2016 Dan Dill [email protected]
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