APPROVAL SHEET
The complete report of Physical Chemistry II Experimen t with the title “Determination of Reaction Order and Constant of Reaction Rate” was made by: name id
: !raeni Rahman :"#"$##%%%"
&ro!p
I:
class
: ICP'of Chemistry
after chec(ed and cons!lted by assistant and assistant coordinator) *o+ this report was accepted)
,a(assar+ o-ember 'ssistantCoordinator+
'ssistant+
Rahmawati0asin ID)"$"$%#"%"2
,!h)Re1(y0!s!f ID)"$"$"#%%".
3nown by+ Responsibility 4ect!rer
Dr) ,!hammad *yahrir+ *)Pd)+ ,)*i ID) "56#%5 %6.%%2 %" .%%#
.%"/
A. TITLE OF EXPERIMENT
Determination of Reaction Order and Constant of Reaction Rate
B. OBJECTIVES
") *how that saponification reaction of ethyl acetate by hydroxide ion is a second order reaction) .) Determine the reaction rate constant of ethyl acetate saponification by hydroxide ion with titration)
C. REVIEW OF LITERATURE
The first steps in the (inetic analysis of reactions are to establish the stoichiometry of the reaction and identify any side reactions) The basic data of chemical (inetics are then the concentrations of the reactants and prod!cts at different times after a reaction has been initiated) The rates of most chemical reactions are sensiti-e to the temperat!re+ so in con-entional experiments the temperat!re of the reaction mixt!re m!st be held constant thro!&ho!t the co!rse of the reaction) This re7!irement p!ts se-ere demands on the desi&n of an experiment 8't(ins+ .%%/: 65"9) 'n elementary reaction is a sin&le reaction step) hen only a sin&le molec!le is in-ol-ed 8';P9 the elementary reaction is !nimolec!lar with a first order rate law 8rate< k='>9) If two reactant molec!les are in-ol-ed 8'?@;P9 the elementary reaction is bimolec!lar with a second order rate law 8rate< k='>=@>9) ' complex reaction is one which proceeds thro!&h more than one constit!ent elementary reaction step) This is the ass!mption that the concentrations of all intermediate species in a reaction mechanism remain constant d!rin& the reaction) Aence the net chan&e in concentration =I> of any intermediate with time can be set to 1ero+ d=I>Bdt% which means that the rates of formation and remo-al for each intermediate m!st balance 8hitta(er+ .%%%: "659)
Consider a reaction of the form ' ? .@ ; $C ? D+ in which at some instant the molar concentration of a participant is => and the -ol!me of the system is constant) The instantaneo!s rate of cons!mption of one of the reactants at a &i-en time is d=R>Bd t+ where R is ' or @) This rate is a positi-e 7!antity 8i&) .")#9) The rate of formation of one of the prod!cts 8C or D+ which we denote P9 is d=P>Bdt 8note the difference in si&n9) This rate is also positi-e) It follows from the stoichiometry for the reaction ' ? .@ ; $C ? D that d [ D] dt
=
[ ]
1 d C 3
dt
=
−d [ A ] dt
=
−1 d [ B ] 2
dt
so the rate of the reaction is related to the rates of chan&e of concentration of prod!cts and reactants in se-eral ways 8't(ins+ .%"%: 6F/9) The o-erall rate law of a complex reaction mechanism is form!lated by combinin& the first and second order rate laws of the constit!ent elementary reactions+ !s!ally by applyin& the steady state ass!mption or+ analo&o!sly+ by ass!min& that some e7!ilibri!m is attained) The form!lated rate law m!st be consistent with the obser-ed rate law) The rate determinin& step is the slowest step in a reaction mechanism) The rate of this reaction determines the maxim!m o-erall rate of formation of prod!cts 8hitta(er+ .%%%: "659)
The rate of reaction is often fo!nd to be proportional to the concentrations of the reactants raised to a power) or example+ the rate of a reaction may be proportional to the molar concentrations of two reactants ' and @+ so we write
v < kr ='>=@> with each concentration raised to the first power) The coefficien t kr is called the rate constant for the reaction) The rate constant is independent of the concentrations b!t depends on the temperat!re) 'n experimentally determined e7!ation of this (ind is called the rate law of the reaction 8't(ins+ .%"%: 6F69) *aponification Reaction of Ethyl 'cetate and *odi!m Aydroxide is an irre-ersible .nd order o-erall+ " st order with respect to reactants f!rthermore reaction order decreases and become se7!ential rather than .nd order when e7!imolec!lar concentrations of both reactants are !sed) This reaction is nonG catalytic and carried o!t in a constant density system) This is a homo&eneo!s phase 8li7!idBli7!id9 reaction and mild exothermic in nat!re) CA$COOC.A2 ? aOA → CA$COOa ? C.A2OA
8,!chtar+ .%"2: #/9)
's the reaction proceeds+ each hydroxide ion remo-ed in the formation of ethanol remo-es one molec!le of ethyl acetate+ bein& the n!mber of moles of either OAG or ethyl acetate so remo-ed+ the concentration of the reactants decreases) If we start with e7!al concentrations of the reactants+ the concentration of aOA can be con-eniently followed at different time inter-als by withdrawin& an ali7!ot from the reaction mixt!re and determinin& the aOA meas!re of the rate of reaction+ so the &reater the -al!e of the rate constant+ the faster the reaction) Each reaction has a definite -al!e of the rate constant at a partic!lar temperat!re and the -al!e of the rate constant for the same reaction chan&es with temperat!re and the -al!es do not depend !pon the concentratio n of reaction b!t depend !pon order of reaction 8I(ha1!an&be+ .%"2: .9) Ethyl acetate saponification reaction with hydroxide ions is not a simple reaction+ b!t it t!rns o!t that this reaction is a second order reaction+ reaction rate law can be &i-en as:
−¿
OH
[
− d ester
]
dt
¿
[
]
= k 1 ester ¿
or as+ dx dt = k 1 ( a− x ) ( b− x )
ith: a < the first concentration of Ester+ in mole 4iter G" b < the first concentration of OA ion+ in mole 4iterG" x < amo!nt mole 4iterG" of ester or base that has reaction (" < constanta of reaction rate 8Team 4ect!rer+ .%"/: "9) ' secondGorder reaction is a reaction whose rate depends on the concentration of one reactant raised to the second power or on the concentrations of two different reactants+ each raised to the first power) The simpler type in-ol-es only one (ind of reactant molec!le: ' → prod!ct here+ rate=
−∆ [ A ] ∆t
rom the rate law+ 2
rate= k [ A ]
's before+ we can determine the !nits of ( by writin& k=
rate
[ A]
2
=
M /s M
2
=
1
M
.s
'nother type of secondGorder reaction is ' ? @ → prod!ct 'nd the rate law is &i-en by rate= k [ A ] [ B ]
The reaction is fi rst order in ' and fi rst order in @+ so it has an o-erall reaction order of .) Hsin& calc!l !s+ we can obtain the followin& expre ssions for “' prod!ct” secondGorder reactions:
→
1
[ A]
=kt +
t
1
[ A]
0
's i&!re "$)"$ shows+ a plot of "B='> t -ers!s t
&i-es a strai&ht line with slope 2 k and
y
intercept < "B='>%) 8The correspondin& e7!ation for “' ? @
→
prod!ct”
reactions
istoocomplexforo!rdisc!ssion)9e
can
obtainane7!ationforthehalfGlifeofa secondGorder reaction by settin& ='> t <='>%B. 8Chan&+ .%"%: 266G26F9)
The optim!m parameters for saponification of PET waste powder were determined by &ra-imetric meas!rement of prod!ct terepthalic acid 8TP'9) 'll (inetics meas!rements were carried at optim!m parameters 8Table "9) In (inetic meas!rements+ three -ertical nec( ro!nd bottom flas( was fixed with refl!xed water condenser+ an internal di&ital temperat!re meas!rement probe+ a cond!cti-ity meas!rin& cell and a microGcontroller based -ertical type stirrer) ' di&ital cond!cti-ity monitorin& instr!ment made of E7!iptronic India 4td) was !sed to meas!re cond!cti-ity) Ai&h precision thermostat and di&ital temperat!re meas!rement probe was !sed in the present wor( 8Patil+ .%"#: "..F9) 'ddition of excess percent of aOA sol!tion plays si&nifica nt ad-anta&e in saponification reaction) 't 2% excess aOA fetched FF increase in rate constant ( beyond which it started showin& depleted res!lts) The rate constant -al!es are show in Table .) @eyond ".%C+ the role play of mass transfer comes in pict!re sim!ltaneo!s to (inetic process) *aponification as s!ch appears to be simple and somewhat fast reaction except the fear of foamin& d!rin& reaction which mi&ht o-erflow the reactor contents) Aowe-er+ cond!ctin& inGsit! saponification in -isco!s base oils in &rease ma(in& is more challen&in& and e7!ally interestin& for the desi&n of &rease (ettlea&itator assembly) Therefore+ On
addition of sodi!m hydroxide 8aOA9 sol!tion to fat+ the density of fat increased and RI decreased 8Patil+ .%"/: 2%"9) D. APPARATUS AND CHEMICALS 1. Apparatus
a) Erlenmeyershaper.2%m4
/pieces
b) Erlenmeyer .2% m4 c) @!rette 2% m4
# pieces pieces .
d) *tatif
pieces .
e) Clamp
pieces .
f)
*pray botte
piece "
&) *topwatch
piece "
h) Drop pipette
pieces $
i)@
pieces .
J)
all pipette Kol!metric flas( 2 m4+ "% m4+ .% m4
() Ro!&h cloth l)
*oft cloth
L" piece piece " piece "
2. C!"#$a%s
a) Ethyl acetate %)%.,
8CA
b) *odi!m Aydroxide %)%., c) Aydrochloricacid%)%.,
COOC.A29
$
8aOA9 8ACl9
d) Phenolphthlein indicator e) ater
8A .O9
E. WOR& PROCEDURES
") Prepared . pieces of Erlenmeyer shap er and &a- e the n!mber 8I and II9 in each Erlenmeyer) .) #% m4 of aOA %)%., was p!tted into Erlenmeyer I) $) #% m4 of CA $COOC.A2 %)%., was p!tted into Erlenmeyer II) #) Prepared sixth Erlenmeyer 8&a-e n!mber "G/9 and p!tted .% m4 of ACl %)%., in each Erlenmeyer)
2) aOA %)%., 8Erlenmeyer I9 an d CA $COOC.A2 %)%., 8Erlenmeyer II9 was mixt!red 8d!rin& mixt!red+ stopwatch was acti-ated9) /) 2 min!tes after reaction was star ted+ "% m4 of mix sol !tion was p!t ted into Erlenmeyer " that contained .% m4 of ACl %)%.,) 6) 'dded $ drops of phenolphthalein indicator into sol!tion) F) The first -ol!me of aOA was record) 5) Erlenmeyer " was titrated by aOA %)%., standard sol!tion) "%) The -ol!me of aOA that !sed wa s record) "") The treatment /G"% was doin& for Erlenmey er .G/ 8at "%+ "2+ .%+ .2 and $% min!tes9)
F. OBSERVATION RESULT
o)
'cti-ities
Res!lt
"
#% m4 of aOA %)%., was p!tted into
Colorless
.
Erlenmeyer I #%m4ofCA $COOC.A2 %)%., was p!tted
Colorless
$
into Erlenmeyer II aOA %)%., and CA $COOC.A2 %)%.,
0ellow and foam
#
was mixt!red .% m4 of ACl %)%., was p!tted into six
Colorless
2
8/9 Erlenmeyer 't t < 2+ "%+ "2+ .%+ .2 and $% min!tes
Colorless
.% m4 of ACl %)%., ? "% m4 of mix /
sol!tion ? $ drops of phenolphthalein Titration with aOA %)%., standard
Kol!me of aOA
sol!tion) a) 2 min!tes b) "% min!tes
$%)2 m4 8pin(9 $%)5 m4 8pin(9
c) "2 min!tes
$")2 m4 8pin(9
d) .% min!tes
$.)2 m4 8pin(9
e) .2 min!tes
$.)5 m4 8pin(9
f)
$$)2 m4 8pin(9
$% min!tes
'. DATA ANAL(SIS 3nown:
, ethyl acetate
< %)%.,
K ethyl acetate
< #% m4
,aOA
<%)%.,
KaOA
<#%m4
M!estion: ( < NNNNNN *ol!tion: ") t < 2 min!tes t < 2 /% s < $%% s K aOA < $%)2 m4 n NaOH = M NaOH × V NaOH
¿ 0.02 M × 30.5 mL ¿ 0.61 mole
NaOH x= n V NaOH
¿
0.61 mole 40 mL −1
¿ 0.0152 mole mL ¿ 0.0152 M
k 1= ¿
¿
¿
1
t
×
1 300 s 1 300 s 1 300 s
0.0152 M
×
( 0.02 M −0.0152 M ) 0.0152 M
×
−3
4.8
−3
4.8 −1
s
M
× 3.17
−1
¿ 0.0106 s
or+
M
0.0152 M
×
−3
¿ 3.33
x
(a−x )
x a ( a− x )
0.0152 M
=
(
0.02 M 0.02 M −0.0152 M
¿
(
−3
0.02 M 4.8
¿
)
0.0152 M
M
)
0.0152 M −5
9.6
M
¿ 158.33
.) t < "% min!tes t < "% /% s < /%% s K aOA < $%)5 m4 n NaOH = M NaOH × V NaOH
¿ 0.02 M × 30.9 mL ¿ 0.618 mole
x=
¿
nNaOH V NaOH
0.618 mole 40 mL −1
¿ 0.0154 mole mL ¿ 0.0154 M
k 2= ¿
¿
¿
1
t
×
1 600 s 1 600 s 1 600 s
x
( a−x ) 0.0154 M
×
( 0.02 M −0.0154 M ) 0.0154 M
×
−3
4.6
×
−3
¿ 1.67
M
0.0154 M −3
4.6 −1
s
M
× 3.35
−1
¿ 0.0056 s
or+ x a ( a− x )
¿
=
0.0154 M
(
0.02 M 0.02 M −0.0154 M
0.0154 M
(
−3
0.02 M 4.6
M
)
)
¿
0.0154 M −5
9.2
M
¿ 167.39
$) t < "2 min!tes t < "2 /% s < 5%% s K aOA < $")2 m4 n NaOH = M NaOH × V NaOH ¿ 0.02 M × 31.5 mL
¿ 0.63 mole
x=
¿
nNaOH V NaOH
0.63 mole 40 mL −1
¿ 0.0158 mole mL ¿ 0.0158 M
k3 = 1 × x t ( a− x )
¿
¿
¿
1 900 s 1 900 s 1 900 s
×
×
0.0158 M
( 0.02 M − 0.0158 M ) 0.0158 M −3
4.2
×
−3
4.2
−3
¿ 1.11
M
0.0158 M
−1
s
M
× 3.76
−1
¿ 0.0042 s
or+ x
¿
(
0.0158 M
=
a a− x
0.02 M 0.02 M −0.0158 M
)
(
−3
0.02 M 4.2
¿
(
0.0158 M
0.0158 M −5
8.4
M
¿ 188.09
#) t < .% min!tes
M
)
)
t < .% /% s < ".%% s K aOA < $.)2 m4 n NaOH = M NaOH × V NaOH
¿ 0.02 M × 32.5 mL ¿ 0.65 mole
x=
¿
nNaOH V NaOH
0.65 mole 40 mL −1
¿ 0.0162 mole mL ¿ 0.0162 M
k 4= ¿
t
x
×
(a−x)
1
×
1200 s 1
¿
¿
1
×
1200 s 1
×
1200 s −4
¿ 8.33
0.0162 M
( 0.02 M −0.0162 M ) 0.0162 M −3
3.8 M 0.0162 M −3
3.8 −1
s
M
× 4.26
−1
¿ 0.0035 s
or+ x a ( a− x )
¿
0.0162 M
=
(
0.02 M 0.02 M −0.0162 M
0.0162 M
(
−3
0.02 M 3.8
¿
M
)
0.0162 M −5
7.6
M
¿ 213.16
2) t < .2 min!tes t < .2 /% s < "2%% s K aOA < $.)5 m4 n NaOH = M NaOH × V NaOH
¿ 0.02 M × 32.9 mL ¿ 0.658 mole
)
x=
¿
nNaOH V NaOH
0.658 mole 40 mL −1
¿ 0.0164 mole mL ¿ 0.0164 M
k5 = ¿
¿
¿
1
x
×
t
( a− x )
1
×
1500 s 1
×
1500 s
×
1500 s
¿ 6.67
0.01664 M −3
M
3.6
1
−4
0.0164 M
( 0.02 M −0.0164 M )
0.0164 M −3
3.6 −1
s
M
× 4.56
−1
¿ 0.0030 s
or+ x a ( a− x )
0.0164 M
=
(
0.02 M 0.02 M −0.0164 M
0.01664 M
¿
(
−3
0.02 M 3.6
¿
M
)
0.0164 M −5
7.2
M
¿ 227.78
/) t < $% min!tes t < $% /% s < "F%% s K aOA < $%)2 m4 n
NaOH
=M
NaOH
×V
NaOH
¿ 0.02 M × 33.5 mL ¿ 0.67 mole
x=
¿
nNaOH V NaOH
0.67 mole 40 mL
)
−1
¿ 0.0168 mole mL ¿ 0.0168 M
k6 =
1
t
x
×
( a− x )
1
¿
¿
¿
0.0168 M
×
1800 s
(
1 1800 s 1 1800 s −4
¿ 5.56
×
0.02 M − 0.0168 M
−3
3.2
×
)
0.0168 M
M
0.0168 M −3
3.2 −1
s
M
× 5.25
−1
¿ 0.0029 s
or+ x a ( a− x )
0.0168 M
=
(
0.02 M 0.02 M −0.0168 M
¿
(
−3
0.02 M 3.2
¿
)
0.0168 M
M
)
0.0168 M −5
6.4
M
¿ 262.5
´= k
k 1+ k 2 + k 3 + k 4 + k 5+ k 6 6
( 0.0010 + 0.0056 + 0.0042 +0.0035 + 0.0030 + 0.0029 ) s
−1
¿
6 −1
¿
0.0202 s 6
−1
¿ 0.0034 s
O ) " . $ # 2 /
8min!tes9 t 2 "% "2 .% .2
%$x8,9 %)%"2. %)%"2# %)%"2F %)%"/. %)%"/# %)%"/F
(8s
G"
9
%)%"%/ %)%%2/ %)%%#. %)%%$2 %)%%$% %)%%.5
x a ( a− x )
"2F)$$ "/6)$5 "FF)%5 ."$)"/ ..6)6F ./.)2%
x
Qraphic ") Relationship between
a ( a− x )
and times)
35 30 f(x) = 5x R² = 1
25 20 15 10 5 0 01234567
t 8min!tes9
H. DISCUSSION Percobaan ini bert!J!an !nt!( menent!(an bahwa rea(si penyab!nan etil
asetat oleh ion hidro(sida adalah rea(si orde (ed!a dan !nt!( menent!(an tetapan laJ! rea(si penyab!nan etil asetat oleh ion hidro(sida den&an cara titrasi) Pada percobaan ini yan& pertama dila(!(an adalah memas!((an masin&G masin& #% m4 lar! tan aOA %+%., dan etil asetat %+%., (e dalam lab! Erlenmeyer bert!t!p) Erlenmeyer bert!t!p di&!na(an a&ar lar!tan tida( ter(ontaminasi den&an !dara l!ar sehin&&a lar!tan terseb!t tida( men&!ap) 'dap!n rea(si yan& terJadi pada saat pencam p!ran aOA den&an etil asetat men&hasil(an &aram dan alcohol) CA$COOA ? OA G → CA$COOG ? C.A2OA aOA ? ACl → aCl ? A.O ACl8sisa9 ? aOA → aCl ? A.O
Camp!ran antara etilasetat den&an aOA har!s ter!s di(oco( a&ar rea(si pen&!raiannya dapat berlan&s!n& ter!s) Pada saat pencamp!ran+ stopwatch diJalan(an dan setelah lima menit lar!tan terseb!t dimas!((an (edalam Erlenmeyer yan& berisis asam (lorida) Penambahan asam (lorida berf!n&si !nt!( men&asam(an camp!ran) *etelah it! dila(!(an penambahan indicator pp !nt!( men&etah!i titi( e(i-alen pada saat dila(!(an titrasi) 3em!dian camp!ran terseb!t se&era dititrasi den&an aOA %+%.,) Perla(!an ini berf!n&si !nt!( men&i(at ACl yan& berlebih sehin&&a rea(si penyab!nannya berhenti) Titrasi dila(!(an den&an cepat a&ar camp!ran lar!tan tida( men&!ap (arena rea(si terseb!t men&hasil(an alcohol yan& m!dah men&!ap) Percobaan ini dila(!(an sebanya( enam (ali titrasi den&an wa(t! lima sampai ti&a p!l!h menit) Kariasi wa(t! terseb!t dit!J!(an a&ar nantinya dapat di&!na(an dalam menent!(an orde rea(si .) Hnt!( setiap titrasi yan& dila(!(an dicatat -ol!me aOA yan& di&!na(an seba&ai data dalam perhit!n&an menent!(an tetapan laJ! rea(si) Dari hasil analisis data diperoleh nilai tetapan laJ! rea(si !nt!( Erlenmeyer " sampai / ya(ni: %+%"%/ s G" %+%%2/ sG" %+%%#. sG" %+%%$2 sG" %+%%$% sG" dan %+%%.5 s G") *ehin&&a diperoleh nilai ( rataGrata ya(ni %+%%$# s
G"
) 'dap!n
berdasar(an &rafi( diperoleh nilai R < "+ yan& berarti bahwa rea(si penyab!nan etilasetat den&a ion hidro(sida mer!pa(an orde rea(si (ed!a)
I. CONCLUSION AND SU ''ESTION 1. C)*$%us#)*
a) *aponification reaction of ethyl acetate by hydroxide ions is second order reaction+ as shown by the -al!e of R < " obtained from the &raph of time with x a ( a− x )
)
b) The reaction rate constant of ethyl acetate saponification by hydroxide ions can be determined by titration+ where titration is performed !sin& %+%., aOA standard sol!tion six times with times -aryin& titration 2. Su++!st#)*s
for f!rther pra(ti(an expected that in doin& a&itation sho!ld be constant and at the time of titr ation to be 7!ic ( so that the res!lts obtained can be maximi1ed
BIBLIO'RAPH(
't(ins+ Peter and !lio De Pa!la) .%%/) Atkins’ Physical Chemistry Eighth Edition) )A) reeman and Company) ew 0or() 't(ins+ Peter and !lio De Pa!la) .%"%) Physical Chemistry Ninth Edition. )A) reeman and Company) ew 0or() Chan&+ Raymond) .%"%) Chemistry Tenth Edition ) ,C Qraw Aill) ew 0or() I(ha1!an&be+ Prosper ,onday Ohien 'nd Oni+ 't 'l) .%"2) Reaction Rate 'nd Rate Constant Of The Aydrolysis Of Ethyl 'cetate ith *odi!m Aydroxide) American Journal Of Scientific And ndustrial !esearch. SSN" #$%&'()*+. ,!(htar+ 'hmad)+ Hmar *hafi7)+ 'li ero1 3han)+ at al) .%"2) Estimation of Parameters of 'rrheni!s E7!ation for Ethyl 'cetate *aponification Reaction) !esearch Journal Of Chemical Sciences. Kol) 28""9) I** ..$"G /%/) Patil+ Dilip)+ KiJendra @atra and *!shil 3apoor) .%"#) Catalytic ,e-olymeriation And /inetics Of Poly0Ethylene Tere-hthalate1 2y Sa-onification. Oriental o!rnal Of Chemistry 'n International Open ree 'ccess+ Peer Re-iewed Research o!rnal) Issn: %56%G%.% ) Kol) $%+ o) 8$9: P&) "..6G".$") Patil) .%"/) Sa-onification of 3anolin for Cosmetic A--lications ) International o!rnal of 'd-anced *cientific and Technical Research Iss!e / -ol!me ") I** ..#5G552#) Team 4ect!re) .%"/) 4uiding Physical Chemistry 3a5 ) Chemistry 4aboratories of ,athematic and at!ral *cience ac!lty) *tate Hni-ersity of ,a(assar) hitta(er)+ ,o!nt and Aeal) .%%% . nstant Notes Physical Chemistry ) @IO* *cientific P!blishers 4imited) Oxford+ H3)
