This experiment involves conducting a saponification reaction between sodium hydroxide (NaOH) and ethyl acetate (Et(Ac)) in a continuous stirred tank reactor (CSTR) to determine the effect of residence time on conversion. A calibration curve will be prepared to relate conductivity measurements to conversion values for the 0.1M NaOH and 0.1M Et(Ac) reaction. The objectives are to determine conversion, the reaction rate constant, and the effect of residence time on conversion.

1. 1
ABSTRACT
This experiment is conducted to carry out manual conversion determination on
experiment samples to verify the conductivity measurement values ,to carry out a
saponification reaction between NaOH and Et(Ac) in CSTR and determine the effect of
residence time onto the reaction extent of conversion also determine the reaction rate
constant .In order to accomplish the objective, the unit being used to perform this
experiment is CSTR 40L. 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 tank reactor. Both of reactants feed to the reactor at equimolar flow rate for a
certain time.From Graph 1 it show that conductivity is decrease proportionally with
conversion.The result show that, when residence time is increase, conversion also
increase by lowering the flow rate. The higher conversion is 98.8% at 45 min residence
time and 0.2 mL/min total flow rate of solution.It can be conclude that the higher the flow
rate , the smaller the reaction rate constant and rate of reaction become highest. From the
calculation , it was obtained that the value of conversion is increase when the volumetric
flow rate decrease.This prove the theory from calibration curve.The rate of reaction is
higher which is ra=2.63x10-3
at the lower rate constant which is k = 68.35. The entire
objectives have been achieved and related to the theory of study .Therefore the
experiment is success.

2. 2
INTRODUCTION
In the industrial chemical processes,mostly a reactor is the key item of equipment in
which raw materials undergo a chemical change to form desired products. The design and
operation of chemical reactors is thus crucial to the whole success of the industrial
operation. There are many types of reactor depending on the nature of the feed materials
and products. Understanding non-steady behavior of process equipment is necessary for
the design and operation of automatic control systems. The rate of reaction is most
important thing will be consider in the reactor because it showed the effectiveness of the
processing of the reactor. One particular type of process equipment is continuous stirred
tank reactor (CSTR).
In a continuous-flow stirred-tank reactor (CSTR), reactants and products are
continuously added and withdrawn from the reactor. In practice, mechanical or hydraulic
agitation is required to achieve uniform composition and temperature, a choice strongly
influenced by process considerations. The CSTR is idealized opposite of the weel - stirred batch
and tubular plug flow reactor. Analysis of selected combination of these reactor types can be
useful in quantitatively evaluating more complex gas , liquid and solid-flow behaviour.
In this experiment , the CSTR (model :BP143 ) unit is suitable for student experiment on
chemical reaction in liquid phase which is under adiabatic and isothermal condition. The unit
consist of jacketed reaction fitted in the agitator and condenser. The unit comes complete with
vessels for raw material and product,feed pumps and thermostat . (www.labequip.com) The
reactor is modeled in order to perform the saponification reaction where the reaction is occur
between the sodium hydroxide , NaOH and ethyl acetate , Et(Ac) . The saponification process
between this compounds produced sodium acetate in a batch and the continuos stirred tank

3. 3
reactor evaluate the rate data needed to design a production scale reactor.
AIMS
In this experiment, there are a few objectives to achieve:
1. To carry out manual conversion determination on experiment samples to verify the
conductivity measurement values
2. To carry out a saponification reaction between NaOH and Et(Ac) in CSTR
3. To determine the effect of residence time onto the reaction extent of conversion
4. To determine the reaction rate constant
THEORY
Saponification is a process by which triglycerides are reacted with sodium or potassium

4. 4
hydroxide (NaOH or KOH) to produce glycerol and fatty acid salt called “soap”. Lipid
that contain fatty acid ester linkages can undergo hydrolysis. (Helmenstine,2001) . The
equation below shows the saponification process between sodium hydroxide and ethyl
acetate ( irreversible reaction) to produce sodium acetate and by product ethanol.
C2H5O2CCH3 + NaOH → CH3CO2Na + H3CCH2OH
Ethyl acetate sodium hydroxide sodium acetate ethanol
Continuous Stirred Tank Reactor(CSTR)
Figure 1
stirred tank
CSTR is used
primarily for
liquid phase reaction. It is normally operated at steady state with continuos flow and is
assumed to be perfectly mixed;consequently, there is no time dependence or position
dependence of the temperature , the concentration or the reaction rate inside the CSTR
(Fogler,2006). The feed assumes a uniform composition throughout the reactor , exit
stream has the same composition as in the tank.
General Mole Balance Equation
FAO – FA + 0
V
∫ rA dv = dNa/dT

5. 5
Assumptions:
For steady state dNA / dt = 0.
Well mixed, therefore rA is the same throughout the reactor.
Rearranging the generation,
vrdvrdvr
v
aa
v
a ∫∫ ==
00
aaao rFFv −−= /)(

6. 6
In terms of conversion,
Preparation of Calibration Curve for Conversion vs Conductivity
A calibration curve is a method used in analytical chemistry to determine the
concentrations an unknown sample solution. It is a graph generated by experimental
means,with the concentration of solution plotted on the x-axis and the observable variable
.
The reaction to be studied is the saponification reaction of ethyl acetate Et(Ac) and
sodium hydroxide (NaOH) . Since this is a second order reaction , the rate of reaction
depends on both concentration of Et (Ac) and NaOH . However for analysis purposes ,
the reaction will be carried out using equimolar feeds of Et(Ac) and NaOH solutions with
aoaao FFFx /)( −=
aao rxFv −= /)(

7. 7
the same initial concentration . This ensures that both concentration are similar
throughout the reaction .
NaOH + Et(Ac) → Na(Ac) + EtOH
In this experiment , it is required to calibrate the conductivity measurement of conversion
values for the reaction between 0.1M ethyl acetate and 0.1M sodium hydroxide.
Residence Time
The reactor`s residence time is defined as the reactor volume divided by the total feed
flow rated

8. 8
Residence time, τ
There are some assumption have been made in order to using residence time
equation, in this experiment to reduce the complexity of the system being modeled. These
O
CSTR
F
v
=

9. 9
assumption include , but are not limited to :steady state in flow and out flow, constant
volume constant temperature and uniform distribution of the substance throughtout the
volume of the system. It also assume that chemical degradation does not occur in the
system in question and the particles do not attach to surfaces that would hinder the flow.
If there are chemical degradation occur in a system, the substances that originally entered
the system may react with other existing compounds and causing the residence time to be
significantly shorter since substance would be chemically consumed and effectively be
removed from the system before it was able to naturally flow out of the system.
(http://en.m.wikipedia.org/wiki/residence_time)
Rate of Equation and Rate Law
The rate of reaction for a reactant and products in a particular reaction can be defined as
how fast or slow the reaction takes place .
Consider the chemical reaction as below:
aA + bB → cC + dD ............(eq 1)
The lowercase letter which a,b, c and d refer to the stoichiometric coefficient while the
capital letter which A,B,C,D refer to the reactant and product.
According to the IUPAC`s Gold Book definition the rate of reaction , r in the
chemical reaction is occur in a closed system which is under a constant - volume
conditions, without build up of reaction intermediates,is defined as :

10. 10
Where [A],[B],[C],[D] are referred to the molarity of the substances . Based on IUPAC
the times must be in second and the rate of reaction in a positive sign.
The mass balance for a system in general is:
IN -OUT + GENERATION- CONSUMPTION = ACCUMULATION
Mass is conservative entity , hence given a control volume V the sum of mass flows
entering the system will be equal to the sum exiting minus (plus) the consumed
(generated) or accumulated fractions.
dt
Dd
ddt
Cd
cdt
Bd
bdt
Ad
a
r
][1][1][1][1
==−=−=

11. 11
APPARATUS
Continuos stirred tank reactor: Model BP143
50ml burrete
200ml beaker
Conical flask
100ml measuring cylinder
Conductivity probe
Solution:
-sodium hydroxide , NaOH (0.1M)
-Ethyl acetate , Et (Ac) (0.1M)
-Deionised water

12. 12
-Phenolphtalein
Figure 1: CSTR (model:BP
143)
PROCEDURES
General Start-Up
Procedures
1. The following solution were prepared
a) 40 L of sodium hydroxide , NaOH (0.1M)
b) 40 L of ethyl acetate , Et (Ac) (0.1M)
c) 1 L of hydrochloric acid , HCL (0.25M) , for quenching
2. All valves were ensure initially closed.
3. The feed vessels were charged as follows:
a) The charge port caps for vessels B1 and B2 were opened.
b) The NaOH solution was carefully poured into vessel B1 and Et (Ac) solution was
poured into vessel B2
c) The charge port caps for both vessels were closed.
4. The power for the control panel was turned on.
5. Sufficient water in thermostat T1 tank was checked. Refill as necessary.
6. The overflow tube was adjusted to give a working volume of 10 L in the reactor R1.

13. 13
7. Valves V2, V3 , V7, V8 and V11
8. The unit was ready for experiment.
General Shut- Down Procedures
1. The cooling water valve V13 was kept open to allow the cooling water to continue
flowing.
2. Both pumps P1 and P2 were switched off. Stirrer M1 was switched off.
3. The thermostat T1 was switched off. T he liquid in the reaction vessel R1 was let to
cool down to room temperature.
4. The cooling water valve V13 was closed.
5. Valves V2, V3 , V7, V8, were closed. Valves V4 , V9 and V12 were opened to drain
any liquid from the unit.
6. The power for the control panel was turned off.

14. 14
Preparation of Calibration Curve for Conversion vs. Conductivity
1. The following solution were prepared:
a) 1 L of sodium hydroxide , NaOH (0.1M)
b) 1 L of sodium acetate , Et (Ac) (0.1M)
c) 1 L of deionised water , H2O
2. The conductivity and NaOH concentration for each conversion value were determined
by mixing the following solution into 100ml of deionised water.
a) 0% conversion :100ml NaOH
b)25% conversion:75ml NaOH + 25 ml Et(Ac)
c)50% conversion: 50ml NaOH + 50ml Et(Ac)
d)75% conversion: 25ml NaOH + 75ml Et(Ac)
e)100% conversion: 100ml Et(Ac)
Back Titration Procedures for Manual Conversion Determination
1. A burette was filled up with 0.1 M NaOH solution
2. 10ml of 0.25 M HCl was measured in a flask

15. 15
3. A 50ml sample was obtained from the experiment and immediate the sample was
added to the HCl in the flask to quench the saponification reaction.
4. A few drops of pH indicator were added into a mixture
5. The mixture was titrated with NaOH solution from the burrete until the mixture was
neutralized. The amount of NaOH titrated was recorded.
Effect of Residence Time of the Reaction in a CSTR
1. The general start up procedures was performed.
2. Both pumps P1 and P2 were switched on simultaneously and valves V5 and V10 were
opened to obtain the highest possible flow rate into the reactor.
3. The reactor was filled up with both of the solution until it is just about to overflow.
4. The valves V5 and V10 were readjusted to give a flow rate of about 0.1L/min . Both
flow rate must be same. The flow rate was recorded.
5. The stirrer M1 was switched on and the speed was set about 200rpm.
6. The conductivity value at Ql-401 was started monitoring until it does not change over
time. This is to ensure that the reactor has reached steady state.
7. The steady state conductivity value was recorded and the concentration of NaOH
extent of conversion in the reactor was found out from the calibration curve.
8. Sampling Valve V12 was opened and a 5oml sample was collected. A back titration
procedure was carry out to determine the concentration of NaOH in the reactor and the

16. 16
extent os conversion .
9. The experiment (steps 5 to 9) was repeated for different residence times by adjusting
the feed flow rates of NaOH and Et(Ac) to about 0.15, 0.20. 0.25, 0.30. Both flow rates
must be same.
RESULTS:
Table 1: Preparation of calibration curve

17. 17
Graph 1:Calibration curve (conductivity vs conversion )
Table of experiment 1
Reactor Volume = 9L
Concentration of NaOH in feed vessel= 0.1M
Concentration of Et(Ac) in feed vessel = 0.1M
Table 2: Result effect residence time of reaction in CSTR
Temperature
(o
C)
27.6 27.6 27.8 27.9 27.9
Flow rate of
NaOH
(mL/min) 0.10 0.15 0.20 0.25 0.30
Flow rate of
Et (Ac)
(mL/min) 0.10 0.15 0.20 0.25 0.30
Total flowrate
, Fo (mL/min)
0.20 0.30 0.40 0.50 0.60
Conductivity 2.53 2.43 2.23 2.11 1.99
Volume of
NaOH titrated,
V1(mL)
24.7 23.8 23.0 22.5 21.9
Residence
time, τ (min)
50.00 33.33 25.00 20.00 16.67
Volume of
unreacted
quenching
HCl, V2 (mL)
9.88 9.52 9.20 9.00 8.76
Volume of
HCl reacted
with NaOH ,
V3 (mL)
9.88
‘
0.48 0.8 1.0 1.24
Conservation
, X (%)
98.8 95.2 92.0 90.0 87.6
Rate Constant
,k
(M-1
s-1
)
2744.44 247.94 115.00 90.00 68.35
Rate of
reaction , -ra
(M/s) 9.9x10-4
1.43x10-3
1.84x10-3
2.25x10-3
2.63x10-3

18. 18
Graph 2: graph conversion X vs residence time

19. 19
CALCULATION
Sample Calculation
Known quantities:
Volume of sample , Vs = 50 ml
Concentration of NaOH in the feed vessel, CNaOH,f =0.1mol/L
Volume of HCl for quenching , VHCl,s = 10mL
Concentration of HCl in standard solution, CHCl,s = 0.25mol/L
Concentration of NaOH used for titration, CNaOH,s = 0.1 mol/L
Volume of titrated NaOH , V1 =24.7 mL
Total flow rate of solution , Fo = 0.1 mL/min
A) Concentration of NaOH entering the reactor , CNaOH,o

20. 20
CNaOH,O=
fNaOHC ,
2
1

21. 21
=
= 0.05 mol/L
)1.0(
2
1

22. 22
B) Volume of unreacted quenching HCl, V2
V2 =
1
,
,
V
C
C
sHCl
sNaOH

23. 23
= 24.7mL
= 9.88 mL
x
25.0
1.0

24. 24
C) Volume of HCl reacted with NaOH in sample , V3
V3 =
= 10 – 9.88
= 0.12 ml
D) Moles of HCl reacted with NaOH in sample, n1
2, VV sHCl −

25. 25
n1 =
=
(0.25x0.12)/1000
=
0.00003 mol
E) Moles of unreacted
NaOH in sample , n2
n2 = n1
= 0.00003 mol
1000
)( 3, xVC sHCl

26. 26
F) Concentration of unreacted NaOH in the reactor , CNaOH
CNaOH =
=(0.00003/ 50)x1000
= 0.0006 mol/L
G)Conversion of NaOH in the reactor , X
10002
x
V
n
s

27. 27
X =
= (1- 0.0006/0.05) x 100%
= 98.8%
H)Residence time ,τ
%1001
0,
x
C
C
NaOH
NaOH








−

28. 28
O
CSTR
F
V

29. 29
τ =
= 10/0.2
= 50min
I) Reaction rate constant , k

30. 30
k =
= ( 0.05 - 0.0006) / (50 x 0.00062)
= 2744.44 M-1
min-1
J) Rate of reaction , -rA
-rA = kCA
2
=2744.44 x 0.00062







 −
2
A
AAo
C
CC
τ

31. 31
= 9.9x 10-4
mol/L.min
DISCUSSION
In this experiment we are investigate about saponification reaction by using
Continuos Stirred Tank Reactors (CSTR) 40L (model:BP 143). This experiment has been
conducted to carry out saponification reaction between NaOH and Et(Ac) to determine
the effect of residence time onto the reaction extent of conversion and the reaction rate
constant , beside to compare with manually conversion. The CSTR model is used to
predict the behaviour of chemical reactors, so the key reactor variables such as the
dimensions of the reactor, can be estimated. Saponification process, it is one kind of
process to make a soap and it is continuos reaction . In this experiment , the reaction of

32. 32
saponification is quenching with hydrochloric acid to stop the reaction. The reaction
rapidly reacts and back titration is done to investigate the volume reacted.
From the data collected , two graph had been plotted which are conductivity versus
conversion for manually conversion experiment and conversion X versus residence time
for reaction in CSTR. The calibration curve is plotted to determine the conductivity of the
reaction between NaOH and Et (Ac) at certain percentage of conversion. From graph 1,
we can conclude that the conductivity is decrease proportionally with conversion. It show
that the conductivity is decreased when the volume of NaOH is decreased. When both
reactant with different moles was used, it will give a significant difference of
conductivity .Because of ethyl acetate as reactant and ethanol as product are not electric
conductor , the conductivity of the mixture measurement can be used to measure the
concentration of unreacted NaOH that remains solution that relate to conversion.
Volumetric flow rate is related to the residence time therefore an experiment is
conduct in varies flow rate which is 0.1, 0.15, 0.20, 0.25 and 0.30 L/min. .From the data
collected , we can conclude that the conversion is increase as the volumetric flow rate is
decrease. Fluid entering the reactor at time t and will exit at time t + τ . Residence time , τ
is time that the fluid elements spend within reactor. At high flow rate, the velocity of
fluid moving inside the reactor is high means the reactant spend less time within the
reactor.From graph 2, we can conclude that conversion is linearly increase with residence
time. It can be conclude that the longer the residence time , the more conversion of the
reactant . The higher conversion is 98.8 % at higher residence time which is 45min.
The equimolar reaction between NaOH and Et(Ac) with the same initial reactant`s

33. 33
concentration is the second order reaction. The rate law is -rA=kCACB .The rate of reaction
is L/mol.s. Relate to the rate constant for this order of reaction ,when the `k` value is
increase means more volume of NaOH require to convert a mole of NaOH in 1 second.
From the calculated result, the reaction rate constant is increase as the volumetric flow
rate is decrease.And when the reaction rate constant decrease , the rate of reaction will
increase. The rate of reaction is higher which is ra=2.63x10-3
at the lower rate constant
which is k = 68.35 . There is more moles of NaOH converted for a less volume of NaOH
solution require. This is very important key design to have a high conversion for large
scale production.
In this experiment , there are some zero error and parallax error occur while taking
the measurement of each data.When taking the reading, the position of eye must be
perpendicular to the reading scale of burette and measuring cylinder. Besides, we have to
rinse all the apparatus before we use it to ensure that all apparatus is clean so that any
chemical put into it does not react with any others chemicals. And the most important is ,
need to immediately added to the HCl in the flask that contain the sample to quench the
saponification reaction also to make sure , the sample does not react with others
chemical.By doing all precaution , we can get better results.
From the all calculation , it was obtained that the value of conversion is increase
when the volumetric flow rate decrease. This proved , the theory from the calibration
curve from the first experiment . Therefore the experiment is success.

34. 34
CONCLUSION
As for the conclusion,the purpose of this experiment to determine the reaction rate
constant and as well as the effect of residence time on the conversion of sodium
hydroxide. CSTR is used in order to achieve the objective of this experiment. By done
this experiment , all purposes are met and the result are collected . From the result it show
the conversion is decrease from 98.8% to 87.6% when the flow rate is increase from 0.20
mL/min to 0.60 mL/min.From the graph conversion versus residence time , it can be
conclude that conversion is increase proportionally with residence time. This proved , the
theory from the calibration curve from the first experiment .When increasing the flow

35. 35
rate , the reaction rate constant become smaller and the rate of reaction become
higher.The experiment is successful because the entire objectives have been achieved and
related to the theory of study .
RECOMMENDATIONS
1. Divide into two teams which is the first team in charge of the CSTR 40L machine
while the second team would carry out the back titration procedures.
2. Make sure all of the valves closed and open as needed and there is no leaks from the
reactor in order to make sure CSTR 40L machine is running appropriately to prevent
harm to the machine and individual that used the machine.
3. Controlled the valve carefully and slowly when adjusting the flow rate to make sure
flow rate will stabilize and the experiment will run smoothly.

36. 36
4. During titration , use the suitable apparatus with appropriate size and scale to the
amount to be measured.
5. Make sure all the error is avoided to get more accurate result.To avoid parallax error ,
make sure the position of eye must be parallel to reading scale.
6. Hydrochloric acid for quenching should be prepared early and added to the samples as
soon as possible so that the reaction between NaOH and Et(Ac) cannot proceed because
the NaOH that`s not reacted will neutralized by HCl.
7. The samples that already mix with HCl should be titrated as soon as possible.
8. Take conductivity reading when the conductivity not changes in time because it change
rapidly in short time.
REFERENCE
1.Fogler, Scott H.Elements of Chemical Reaction Engineering , 4th
ed. Englewood Cliffs,
NJ:Prentice hall,2006. Page 12,40
2.Levenspiel,O,Chemical Reaction Engineering , 3rd
ed, John Wiley and Sons , New
York , 1999.page 35
3.Thomas, Charles E.Process Technology Equipment and System 3rd
edition .Clifton
Park, NY: Delmarcangage Learning , 2011.

37. 37
4.Gilbert F.Froment and Kenneth B.Bischoff.,`Chemical Reactor Analysis and Design,
John wiley &sons , 2th ed ,1990
5.Molarities and dilutions access on 21/03/2015 at [ www.microbiologybytes.com]
6.Mass-mole concentration access on 21/03/2015 at [www.ausetute.com.au]
7.Saponification Definition access on 20/03/2015 at [ chemistry.about.com]
8.Continuos Stirred Tank Reactor access on 20/03/2015 at [www.labequip.co.za]
9.CSTR 40L -CPE554 access on 20/03/2015 at [www.coursehero.com]
10.CSTR 40L access on 19/03/2015 at [www.scribd.com]
11.Residence time access on 19/03/2015 at http://en.m.wikipedia.org/wiki/residence_time
APPENDICES