Sem 4 Lab 1 - Copy (1).Docx

ABSTRACT/SUMMARY

This experiment is conducted to carry out conversion determination on experiment samples manually to verity the conductivity measurement values, determine the effect of residence time onto the reaction extent of conversion and the reaction rate constant. In order to accomplish the objective, the unit being used to perform this experiment is CSTR 4!. The design of the reactor is very important to the success of the production. In this experiment sodium hydroxide and ethyl acetate react in continuous stirred tan" reactor. #oth of reactants feed to the reactor at e$uimolar flo% rate for a certain time. &orm graph ' it sho%s that conductivity is decrease proportionally %ith conversion. &or the graph ( the result sho%s that, %hen residence time is increase, conversion also increase by lo%ering the flo% rate. The higher conversion is )(.4* at ( min residence time and .( m!+min total flo% rate of solution. It can be conclude that the higher the flo% rate, the smaller the reaction rate constant and rate of reaction become highest.

INTRODUCTION

In the industrial chemical process, mostly a reactor is the "ey part of e$uipment in %hich ra% material undergoes a chemical change to form desired product. The design and operation of chemical reactor is thus crucial to the %hole success of the industrial operation. There are many type of reactor depending on the nature of the feed materials and products. Reactor is the heart of any process in industry. Reactor can be classified into t%o types  continuous stirred tan" reactor and a plug flo% reactor. #oth of this type of reactor can be operate in a continuous and a batch mode depending on the nature of the reaction. Reactor can be e$uips %ith a heating or cooling coil for heating process or cooling process. It is depending on the nature of reaction %hich is exothermic or endothermic. - reactor also can be e$uip %ith bed of catalyst for a better reaction processes.

Reactor is one of the most important parts in industrial sector. Reactor is e$uipment that changes the ra% material to the product that %e %ant. - good reactor %ill give a high production and economical. ne of criteria to choose or to design a good reactor is to "no% the effectiveness of the reactor itself. There a many types of reactor depending on the nature of the feed materials and products. ne of the most important in the various chemical reactions %as the rate of the reaction.

- stirred tan" reactor /STR0 may be operated either as a batch reactor or as a steady state flo% reactor /CSTR0. The "ey or main feature of this reactor is that mixing is complete so that properties such as temperature and concentration of the reaction mixture are uniform in all parts of the vessel. 1aterial balance of a general chemical reaction described belo%. The conservation principle re$uires that the mass of species - in an element of reactor volume d2 obeys the follo%ing statement described belo%. (Rate of A into volume element) - (rate of A out of volume element) + (rate of A ro!u"e! #it$in volume element) % ( rate of A a""umulate! #it$in vol& element)

OB'CTIS

'.To verify the conductivity values by manual determination on experimental samples. (.To determine the effect of residence time onto the reaction extent of conversion. 3.To determine the reaction rate constant

T*ORY

Rate of e$uation and rate la% The rate of reactions or speed of reaction for a reactant and products in particular reaction scan be defined as ho% fast or slo% the reaction ta"es place. &or examples is about the oxidation process bet%een iron under the atmospheric is undergoes a slo% reaction compare to the combustion of butane in a fire that can be categories as fast reaction. Consider the chemical reaction as belo%

The lo%ercase letter %hich are a,b,p,and $ refer to the stoichiometric coefficient %hile the capital letter %hich are -,#,5 and 6 refer to the reactants and products. -ccording to the I75-C8s 9old #oo" definition the rate of reaction, r in the chemical reaction is occur in a closed system %hich is under a constant:volume conditions, %ithout build up of reaction intermediates, is defines as

;here mixed

therefore

is

the

same

throughout

the

reactor.

Rearranging the generation, 2 B /&-o:&-0+ >rIn terms of conversion,  B /& -o:&-0 + &-o 2 B /&

0 + >r-

-o

- calibration curve is a method used in analytical chemistry to determine the concentration of an un"no%n sample solution. It is a graph generated by experimental means, %ith the concentration of solution plotted on the x>axis and the observable variableDfor example, the solution8s absorbanceDplotted on the y>axis. The curve is constructed by measuring the concentration and absorbance of several prepared solutions, called calibrat ion standards. nce the curve has been plotted, the concentration of the un"no%n solution can be determined by placing it on the curve based on its absorbance or other observable variable.

Residence Time The reactor8s residence time is defined as the reactor volume divided by the total feed flo% rates.

Residence time is a probability distribution function that describes the amount of time a fluid element could spend inside the reactor. Residence time %idely use to characteriEe the mixing and flo% %ithin reactors and to compare the behavior of real reactors to their ideal models. This is useful, not only for troubleshooting existing reactors, but in estimating the yield of a given reaction and designing future reactors.

A,,ARATUS

'. Continuous stirred tan" reactor. 1odel #5 '43 (. F m! burette 3. ( m! bea"er 4. Conical flas" F. Solution  I>Sodium hydroxide, AaG /.'10 II>@thyl acetate, @t /-c0 /.'10 III>Heionised %ater I2>5henolphthalein . Conductivity probe J. ' m! measuring cylinder.

O,RATIN ,ROCDURS

9eneral Start>7p 5rocedures '. The follo%ing solutions have been prepared for the expirement a0 4 ! of sodium hydroxide, AaG /.'10 b0 4 ! of ethyl acetate, @t/-c0 /.'10 c0 ' ! of hydrochloric acid, GC! /.(F10, for $uenching (. -ll the valves %as ensured initially closed. 3. The feed vessels %as charged as follo%s a0 The charge port caps %as opened for vessels #' and #(. b0 AaG solution %as carefully pour into vessel #' and the @t/-c0 solution into vessel #(. c0 The charge port caps closed for both vessels. 4. The po%er %as turn on for the control panel. F. Chec"ed that there is sufficient %ater in the thermostat T' tan". Refill if necessary. . pened cooling %ater valve 2'3 and let the cooling %ater flo% through the condenser ;'. /nly for @xperiment (0 J. -djusted the overflo% tube to give a %or"ing volume of ' ! in the reactor R'. K. The valves 2(, 23, 2J, 2K and 2'' %as opened. ). The unit is no% ready for experiment.

9eneral Shut>Ho%n 5rocedures '. The cooling %ater valve 2'3 %as open to allo% the cooling %ater to continue flo%ing. (. #oth pumps 5' and 5( %as s%itch off. Then, s%itch off stirrer 1'. 3. The thermostat T' %as s%itch off. !et the li$uid in the reaction vessel R' cool do%n to room temperature. 4. Closed cooling %ater valve 2'3. F. Closed valves 2(, 23, 2J and 2K. 2alves 24, 2) and 2'( %as open to drain any li$uid from the unit. . The po%er %as turn off for the control panel. 5reparation of Calibration Curve for Conversion vs Conductivity

'.The follo%ing solution %ere prepared i> ' ! of sodium hydroxide, AaG /.'10 ii> ' ! of sodium acetate , @t /-c0 /.'10 iii> ' ! of deionised %ater, G (. (. The conductivity and AaG concentration for each value %ere determined by mixing the follo%ing solution into ' m! of deionised %ater. i> * conversion  ' m! AaG ii> (F* cinversion  JF m! AaG L (F m! @t /-c0 iii> F* conversion  F m! AaG L F m! @t /-c0 iv> JF* conversion  (3 m! AaG L JF m! @t /-c0 v> '* conversion  ' m! @t /-c0 @xperiment ' #ac" Titration 5rocedures for 1anual Conversion Hetermination '.- burette %as filled up %ith .' 1 AaG solution. (.' m! of .(F 1 GCl %as measured in a flas". 3.- F m! sample %as obtained from the experiment and immediate the sample %as added to the GCl in the flas" to $uench the saponification reaction. 4.- fe% drops of pG indicator %ere added into the mixture. F.The mixture %as titrated %ith AaG solution from the burette until the mixture %as neutraliEed. The amount of AaG titrated %as recorded.

@xperiment ( @ffect of Residence Time of The Reaction in a CSTR '.The general start>up procedures %as performed. (.5ump ' and pump ( %ere s%itched on and valves 2F and 2' %ere opened to obtain the highest possible flo% rate into the reactor.

3.The reactor %as filled up %ith both of the solution until it is just about to overflo%. 4.2alves 2F and 2' %ere readjusted to give a flo% rate of about .' !+min. the flo% rate for both valves must be same. The flo% rate %as recorded into a data. F. The stirrer 1' %as s%itched on and the speed %as set about ( rpm. . The conductivity value at 6' %as started monitoring until it does not change over time. This is to ensure that the reactor has reached steady state. J. The steady state conductivity value %as recorded and the concentration of AaG andextent of conversion in the reactor %as found out from the calibration curve. K. Sampling valve 2'( %as opened and 'm! of sample %as collected. It directly proceed %ith the bac" titration procedures to manually determine the concentration of AaG in the reactor and extent of conversion. ).The experiments %as repeated /steps F>)0 for different residence times by adjusting the feed flo% rate of AaG and @t/-c0 to about .'F, .(, .(F, and .3 !+min. the flo% rate for both must be same.

Re.ult.

Table for preparation of calibration curve Conductivit Conversion

Solution1ixtures

Concentration .'

* (F* F* JF* '*

.' 1 AaG 'm! JFm! Fm! (Fm!

y

1 @t G(  'm! 'm! 'm! 'm! 'm!

/-c0 (Fm! Fm! JFm! 'm!

ofAaG/10 .F .3JF .(F .'(F .

/ms+cm0 '4.4K '.FJ J.' (.3' .'

Conductivity vs Conversion 20 15

Conductivity (ms/cm)

10

f(x) = - 14.81x+ 14.3 R² = 0.99

Conductivity (m!cm) "in#$ (Conductivity (m!cm))

5 0 0%

50%

100%

150%

Conversion %

9raph ' Calibration curve for conductivity vs conversion

#ac" titration for manual conversion determination

Sample ' ( 3 4 F

2ol. of AaG/m!0 (3.' ('.( ').4 '). 'K.

Table of experiment ' and ( Reactor volume B 4 ! Concentration of AaG in feed vessel B .' 1 Concentration of @t/-c0 in feed vessel B .' 1 Ao.

'. (. 3. 4. F.

&lo% rate of

&lo% rate of

Resisdence

Conductivit

@xit

Conversion

AaG

@t/-c0

time,

y

concentration

,  /*0

/m!+min0

/m!+min0

M /min0

/mS+cm0

of AaG,C AaG

.' .'F .( .(F .3

.' .'F .( .(F .3

(. '33.33 '. K. .J

'.' (.3 3.(' 3.4' 3.JK

/10 .3K .J .''( .'( .'(K

Reaction rate constant, "

Rate of reaction, >r

/1>'min>'0 'F.))J F.FJ 3.'( 3.()J

/mol+!.min0 .(3' .3'K .3JK .4JF

-

)(.4 K4.K JJ. J. J4.4

3.4FF

.FFK

Residence time vs Conversion 100 90 80 '0 &0

Conv#ion  (%)

R#id#nc# tim#* (min) 50 40 30 20 10 0 &0

80

100

120

140

9raph ( residence time vs conversion

SAM, CACUATIONS

'0 &B .'L.' B .( !+min Nno%n $uantities 2olume of sample, 2sB F m!

1&0

180

200

220

Concentration of AaG in the feed vessel, C AaG,f B .' mol+! 2olume of GC! for $uenching, 2GCl,sB ' m! Concentration of GCl in standard solution, C GClsB .(F mol+! 2olume of titrated AaG, 2'B ).K m! Concentration of AaG used for titration, C AaGsB .' mol+!

I.

Concentration of AaG that entering the reactor, C C AaGoB O C AaGf B O /.'0 B .F mol+!

ii.

2olume of unreacted $uenching GCl,2

(

2(B /C AaGs+ CGCls0 x 2' B /.'+.(F0 x (3.' B ).(4 m! iii.

2olume of GCl reacted %ith AaGin sample, 2 23B 2GCls : 2( B ' : ).(4 B .J

iv.

1oles of GCl reacted %ith AaG in sample, n n'B /CGCls x 230 + ' B .(F x .J+'

'

3

.

AaGo

B .') mol

v.

1oles of unreacted AaG in sample, n( n(B n' B .') mol

vi.

Concentration of unreacted AaG in the reactor, C C AaGB n(+2s x ' B .')+F x ' B .3K mol+!

2ii.

Conversion of AaG in the reactor,   B /'> C AaG+ C AaGo0 x '* B /': .3K+.F0 x '* B )(.4 *

2iii.

Residence time, M M B2CSTR + &o B 4 + .( B ( min

ix.

Reaction rate constant, " " B / C-o : C-0 + MC-( B / .F : .3K0 + /( x . (0 B 'F.))J 1>'min>'

AaG

x.

Rate of reaction, >r

-

>r -B "C-( B 'F.))J x .3K(

DISCUSSION

-ccording to the experiment that had been conducted, there are three objectives need to achieve %hich are to carry out the saponification process bet%een AaG and @t /-c0 in a CSTR reactor, to determine the effect of the residence time onto the reaction extent of conversion and lastly to

determine the constant rate of reaction. &rom the data collected, t%o graph had been plotted %hich are conductivity versus conversion and residence time versus conversion. &rom the graph ', it sho%s that the conductivity is constantly decreasing %hich are the line is inversely proportional until at F* conversion %hich is the conductivity is J.' mS+cm but then it suddenly decrease at * conversion until K* conversion %hich is give a curve on the graph as sho%n. &or the second graph %hich is residence time versus conversion, the graph can be concluded that the residence time is increase proportionally to the conversion. It can be conclude that residence is higher if the conversion is higher. #ut there are certain fluctuated pea" %hich due to the error that may be affects the result and graph. -s the result for rates of constant is not correspond to the theory, thus there are some errors occurred during this experiment such as %hile ta"ing the reading of the burette the position of the eyes is not at the same level of the meniscus. So, to improve the reading and get the better results, the positions of the eyes must be parallel to the meniscus. #esides, %e have to rinse all the apparatus before %e use it. This is to ensure that all the bea"ers, or burette is clean so that any chemical that %e put into these apparatus does not react %ith any others chemicals .by doing all these precaution, %e can get more accurate reading and thus improve the results. CONCUSION

#ased on the objectives of this experiment, %hich is to determine the residence time on to the reaction extent of conversion, the relationship conversion and residence time %as directly proportional. #ut the reaction rates constant %ere determined for all varies flo% rate. &rom the calculated data, the rate constant of reaction is increasing %hen the conversion is higher. This can conclude that the experiment %as successfully conducted since it give the right and verified result. RCOMMNDATIONS

'. 1a"e sure reactor does not have any lea"s and valve closed and opened as needed, controlled the valve carefully and slo%ly %hen adjusting the flo% rate to obtain .' !+min. It is to ma"e sure flo% rate %ill stabiliEe and the experiment %ill run smoothly.

(. Repeat titrations t%o or three times because a lot of error comes from titration or use another method other than titration. 3. Hivide into t%o teams %hich is the first team in charge of the CSTR 4 liters machine %hile the second team %ould carry out the bac" titration procedures. 4. Ta"e conductivity reading %hen the conductivity not changes in time because it can change rapidly in short of time. F. 1a"e sure CSTR 4 liters machine is running appropriately, it to prevent harm to the machine and individual that used the machine.

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