lecture 3j hj hj
TRANSCRIPT
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Course Outline• Introduction to Chemical Kinetics
• Determining rates of reactions
• Orders of reactions
• Rate laws
• The integration method/ plots
• Half-life and time constant
• Initial Rate & Isolation methods
• Collision Theor !s Transition "tate Theor
• Temperature effect on rates# $rrhenius
• Chain Reactions# "tead state appro%imation
•Opposing Reactions• -
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Rate e)uation
• Rate e)uation*
• Rate laws ha!e + uses• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• Tae the e)uation
aA + bB cC + dD
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$lthough the order of areaction does not
,,,,,,,,,,,,,,,,,1
it is ,,,,,,,,,, for itto (e so2
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Order of reaction and molecularit
• ORD3R O4 R3$CTIO5
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,, • 6O'3C7'$RIT8
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,
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3lementar and composite reactions
• 3lementar Reaction
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,, • Composite Reaction
• ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,
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6O'3C7'$RIT8• Two main tpes of Elementary Reactions
• ,,,,,,,,,,,,,,,, 9 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
9 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
9 ,,,,,,,,,,,,,,,,,,R3$CTIO5 KI53TIC"
9 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• ,,,,,,,,,,,,,,,,,
9 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9 ,,,,,,,,,,,,,,,,,, R3$CTIO5 KI53TIC"
9 ,,,,,,,,,,,,,,,,,,
,,,,,,,,,, elementar reactions are ________________
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Consider this reaction
• Is this elementar or composite:
• 5eed to identif if ,,,,,,,,,,,,,,,,,,,,
If es ,,,,,,,,,,,,,,,,,,,
If no ,,,,,,,,,,,,,,,,,,,,,
• If elementar1 inetics are ,,,,,,,,,,,,,,
• If composite1 inetics ,,,,,,,,,,,,,,,,,,
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ac to the e%ample
• Is this elementar or composite:
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• Important step is
• This step in!ol!es ,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• HO;3
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Composite reaction rates =cont>d?
• The o!erall rate of reaction was measurede%perimentall
• "o1 for composite reactions1 the rate ofreaction ,,,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
∝ H@0
• Reaction is ,,,,,,, order in H@01 (ut not in
r @0- =see $tins ,,,,,,, for full rate law?
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"o1 for composite reactions
,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
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$nother e%ample• Decomposition of diaAomethane
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• Is the reaction elementar or composite:
• Thus1 what is the molecularit:
• Therefore1 what is the rate law:
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
CH+5@CH+ @CH+. B 5@
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One more e%ample• Com(ination of two radicals
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
• Is the reaction elementar or composite:
• Thus1 what is the molecularit:
• Therefore1 what is the rate law:
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
H2 B r
2 Hr
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Order and 6olecularit
• ___________ is the e to the reaction mechanism2
• $ unimolecular reaction is __________________2
9 e2g2 radioacti!e deca is ,,,,,,,,,,,,,,,2
• $ bimolecular reaction is ___________________2
• IT I"
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• _________________ are the key to kinetics asthe are the ________________ from which we
mae up the _____________________.• To determine the rate law ou need to ______
____________________________1 with easildefined rate laws2
• Thus for a _________________ the rate law is
$ ,,,,,,,,,,,,,,
• this is a ___________________ reaction
• for a ______________________ the rate law is
$ B ,,,,,,,,,,,,,,
• this is a ___________________ reaction
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uestions
E2 Define the following terms# i? elementar reaction1 ii?composite reaction1 iii? molecularit and i!? reaction
order2
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uestions
@2 "tate whether this reaction is liel to (e elementaror composite1 gi!en that the rate law is v . 5@OF02
+2 If the following general reaction is nown to (e
elementar1 what is the rate e)uation:
5@OF=g? B 5O=g? +5O@=g?
@$=g? =g? B C=g?