ice 204_chp3_non catalytic reaction kinetics

8/13/2019 Ice 204_chp3_non Catalytic Reaction Kinetics

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CE 204 K NET KA & KATAL S S CHAPTER 3

CHP 3 NON CATALYTIC & HOMOGENEOUS

REACTION KINETICS

This section covers hoo!eneo"s re#ction r#te e$%ressions the r#tes o'

irreversi()e reversi()e #n* co%)e$ re#ctions

Missen Ch#%ter + , - Sith Ch#%ter .

3/0 R#te o' SIMPLE hoo!eneo"s re#ctions the e''ect o' re#ct#nt

concentr#tions#n* re#ction te%er#t"re 1T2/

kA B C D + +

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The r#te )# 'or HOMOGENEOUS re#ctions 4

r 567 o)/8

90

/tie

90

6 :/CAn

/C;

1%oer )#2

< in ost c#ses ONLY re#ct#nt concentr#tions #''ect r


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k = A.eEa

RT

1Arrheni"s E?"#tion2

NOTE 4 in #**ition to the %oer )# 1#s #n e%iric#) r#te )#2 #(ove there

is #)so # r#te )# constr"cte* (#se* on conce%ts o' re#ction ech#nis/

S"ch r#te )# is c#))e* fundamental r#te )# 1see Ch% @ Missen2/ The )#tter

c#n (e e$tr#%o)#te* o"tsi*e the e$%erient#) con*itions r#n!e/

e!4 ( ) 2( ) 2( )1

2

Pt

g g gCO O CO+

# 1'"n*#ent#)2 r#te )# *erive* 'ro re#ction ech#nis is 4

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1/2

CO O2

1/2

CO O2

k(T).C .C( )

[1 + K(T).C '( ).C ]CO

rK T

=

+

3/0/0/ irst Or*er Re#ction

r 6 :/CA

In const#nt vo)"e(#tch re#ctor #t t 6 B CA6 CAo4

A( ) k.CA

A

dCr

dt = =

CAvs t 6 : 6

3/0/./ Secon* Or*er Re#ction

r 6 :/CA.

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D in const#nt vo)"e(#tch re#ctor #t t 6 B CA6 CAo4

2

A( ) k.CA

AdC r

dt = =

CAvs t 6 : 6

r 6 :/CA/C;

DD in const#nt vo)"e(#tch re#ctor #t t 6 B CA6 CAo C;6 C;o4

( ) k.C .A A A BdC

r Cdt

= =

CAvs t 6 : 6 1!o to %#!e 0+2

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EAMPLE D 04

At ,0F oC #cet#)*eh=*e v#%or *eco%oses into eth#ne #n* c#r(on ono$i*e4

COCHCOCH k

+ 43

Hinse)oo* & H"tchison 10.2 c#rrie* o"t #n e$%erient in # const#nt9vo)"e

(#tch re#ctor/ The initi#) %ress"re o' CH3CO #s +F/+ :P# #n* the 'o))oin!

incre#ses o' %ress"re 1P2 ere note*t 1s2 +. 0B, .+. +FB F+B 0++BP 1:P#2 +/, / 0@/ .,/ 3./, 3@/eterine the re#ction or*er #n* c#)c")#te the r#te const#nt 1in %ress"re #n*

o)#r "nits2/

3/0/3/ Thir* Or*er Re#ction

r 6 :/CA./C;

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In const#nt vo)"e(#tch re#ctor #t t 6 B CA6 CAo C;6 C;o4

2

A( ) k.C .A

A BdC r C

dt = =

CAvs t 6 : 6 >>> Re#* Missen %#!e @. @, JJ

3/0/+/ n9th Or*er Re#ction

r 6 :/CAn

In const#nt vo)"e(#tch re#ctor #t t 6 B CA6 CAo4

A( ) k.CnA A

dCr

dt

= =

or n 6 0 #n* n 0 'in* CAvs t 6 : 6

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SUMMARY4

1i2 re#ction or*er 0 or . is nor#))= 'or si%)e e)eent#r= re#ctions

1ii2 re#ction or*er B is nor#))= NOT o(serve* 'or re#ction in #

sin!)e9%h#se ')"i* ("t it #= occ"r in en=e re#ctions #n* in

the c#se o' !#s 1so)i* c#t#)=e*2 re#ctions re'er to Missen Ch% F

& 0B

1iii2 re#ction or*er 3 is r#re ("t inc)"*es4 the !#s %h#se re#ction

(eteen NO #n* O.or H.or C).or ;r. #ci*s or (#ses c#t#)=e*

re#ctions in #?"eo"s %h#se

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1iv2 re#ction or*er #= (e other n"(ers 1even ne!#tiveJ2 e! "n*er

cert#in con*itions the *eco%osition o' CH3COH is 3.9or*er

re#ction (eteen CO 109or*er2 #n* C).13.9or*er2 to 'or COC)./

1v2 re#ction r#te #= #)so *e%en* on the %ro*"ct concentr#tion i'

the or*er is - the e''ect is :non #s #"toc#t#)=sis ("t i' the or*er

is the e''ect is c#))e* %ro*"ct inhi(ition 1coon in c#t#)=tic

re#ction2/ This e''ect c#n (e :non i' e#s"reents #t )o

re#ct#nt9conversions #re con*"cte*/ Re'er to Missen Ch% F

3/0/,/ E''ect o' T

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T #''ects the r#te #s in*ic#te* in Arrheni"s e?"#tion/ The v#)"es o' A

#n* EA#= (e esti#te* "sin! the )ine#rie* 'or

1ln k = ln A - ( )

Ea

R T

EAMPLE D .4

eterine the Arrheni"s %#r#eters 'or the re#ction

2 4 4 6 6 1

kC H C H C H +

The 'o))oin! *#t# #s co))ecte* (= Ro)e= & Steiner 10,024

T 1K2 : 1L/o)90/s902 T 1K2 : 1L/o)90/s902

@B B/3F F3 3/0.@FB B/, F +/B,

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FB3 B/+ F@ 3/+@F3. 0/,@ F@ 3/@+

F.. 0/3+ F+ ,/.F.3 0/.3 .0 F/.BF. 0/,

3/. R#te o' RE8ERSI;LE hoo!eneo"s re#ctions

M#n= re#ctions #re reversi()e in hich re#ction thero*=n#ics #%%)=

1ree(er Ch#%ter .J2/ The r#te on)= e#s"res ch#n!es PRIOR TO the

e?"i)i(ri" con*ition/ In the #= to e?"i)i(ri" the r#te *iinishes #n* ne#r

e?"i)i(ri" r B/ E$#%)es o' reversi()e re#ctions41

4 1 4 11

k

kn C H i C H

2

2 2 32

1

2

k

kSO O SO

+

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3

3 3 2 3 33

k

kCH COOCH H O CH COOH CH OH

+ +

EAMPLE D 34

The isoeri#tion o' A to 'o))os 'irst or*er in (oth *irections

1

1

k

kA D

o))oin! *#t# ere o(t#ine* #t # cert#in T 'ro # const#nt9vo)"e (#tch

re#ctor4

t 1h2 B 0 . 3 + 1 CACAB 0BB @./, ,/F +,/ 3/, 3B'in* the v#)"es o' :0 #n* :90/

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T#()e ./0B R#te E?"#tion 'or si%)e re#ctions

1% F. Sith re#* #)so % . @+2


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3/3 R#te o' COMPLE hoo!eneo"s re#ctions

T=%es o' co%)e$ re#ctions4

- P#r#))e) re#ctions e!4

2 5 2 4 2C H OH C H H O +

2 5 2 4 2

C H OH C H O H +

6 5 2 3 6 4 2 2 2( )C H NO HNO o C H NO H O+ +

6 5 2 3 6 4 2 2 2( )C H NO HNO m C H NO H O+ +

6 5 2 3 6 4 2 2 2( )C H NO HNO p C H NO H O+ +

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- Series re#ctions e!4

3 2 4 2( )CH CO CH CH CO +

2 2 4

1

2CH CO C H CO +

- Series & reversi()e e!4

2 5 2 4 2

1

2N O N O O +

2 4 22N O NO

- Series & %#r#))e) e!4

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4 2 2CH O HCHO H O+ +

2 21/ 2HCHO O CO H O+ +

4 2 2 22 2CH O CO H O+ +

NOTE4

or # co%)e$ re#ction s=ste e c#n 'in* the #$i" n"(er o' )ine#r)=

in*e%en*entcheic#) e?"#tions 1TTSLre#ction inAzas TK2/ The n"(er te))s

"s the ini" n"(er o' s%ecies th#t nee* to (e #n#)=e* in # :inetic st"*=/

Hoever those e?"#tions h#ve NOTHING to *o ith the :inetics 1re#) re#ctions

or ech#nis2/ ;"t the= c#n (e "se'") 'or #ss (#)#nce %"r%oses/ Re#* ,/./0

Missen % BJJ

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3/3/0 P#r#))e) re#ctions

The (most common) conversion, yield and selectivity in parallel reactions:

A B P+

A B S+

Conversion 6

( )A A

A

C C

C

Se)ectivit= to P 6( )

P

A A

C

C C

Yie)* o' P 6

P

A

C

CYie)* 6 conversion $ se)ectivit=

EAMPLE D +4

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escri(e ho e$%erients in # const#nt9vo)"e (#tch re#ctor sho")* (e

c#rrie* o"t to e#s"re :0#n* :.'or these 0stor*er %#r#))e) re#ctions4

A B C + r;6 :0/CA

A D E + r6 :./CA

3/3/. Series re#ctions

1 2k kA B C

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T=%ic#) concentr#tion %ro'i)e in # (#tch re#ctor

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EAMPLE D ,4

escri(e ho e$%erients in # const#nt9vo)"e (#tch re#ctor sho")* (e

c#rrie* o"t to e#s"re :0#n* :.'or # 0stor*er series re#ctions

HOMEORK

0/ or the series re#ction #(ove c#)c")#te the tie #t hich the C;is

#$i" #n* h#t is the C;#$i" i' initi#))= CA6 CAB#n* C;6 CC6 B/

./ An e)eent#r= reversi()e )i?"i* %h#se re#ction1

1

k

kA R

is c#rrie* o"t

isother#))= in # const#nt9vo)"e (#tch re#ctor/ A'ter F in"tes A

conversion is 03 #n* #t e?"i)i(ri" A conversion is .3/ C#)c")#te the r#te

const#nts/

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3/3/3 Series9%#r#))e) re#ctions 1see Levens%ie) Cheic#) Re#ction En!ineerin! 3r*e*ition %

0FF & 0B2

1kA B R+

2kR B S+

I' the in*ivi*"#) re#ctions 'o))o 0

st

or*er in res%ect to e#ch re#ct#nt4

19rA2 6 :0/CA/C; rR6 :0/CA/C;9 :./CR/C;

19r;2 6 :0/CA/C;- :./CR/C; rS6 :./CR/C;

Mo) (#)#nces4

CAB CA 6 CR CRB- CS CSB C;B C; 6 CR CRB- .1CS CSB2

MORE EERCISES4 Hi)) e$#%)es ,90 ,93 "% to ,9

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ice 204_chp3_non catalytic reaction kinetics

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