Nirma University
Institute of Technology
Chemical Engineering Department
Lab Manual -CRE-Is
Chemical Reaction Engineering-I
Laboratory Manual
2CH 312
Nirma University
Institute of Technology
Chemical Engineering Department
Nirma University
Institute of Technology
Chemical Engineering Department
Lab Manual -CRE-Is
Date:
Experiment No:
INTEGRAL METHOD OF ANALYSIS – I
(Equimolar n-Ethyl Acetate –Sodium Hydroxide System)
AIM: To determine the kinetics of reaction between n-Ethyl Acetate and sodium
hydroxide at room temperature by the integral method of analysis.
APPARATUS: 500-ml beaker, Conductivity meter.
CHEMICALS: n-Ethyl Acetate, sodium Hydroxide, distilled water.
THEORY:
In integral method of Analysis the rate of reaction is assumed and based on that
integrated rate expression is obtained. Based on this suitable graph is drawn if straight
line obtained then the assumed order is correct. It is also used to find rate constant at
particular temperature.
NaOH + CH3COOC2H5  CH3COONa + C2H5OH
PROCEDURE:
200 ml of (0.1 M) NaOH is taken in 500 ml beaker, which serves as batch reactor. To this
200 ml of n-Ethyl acetate (0.1 M) is added and contents are kept well stirred. After
adding n-Ethyl acetate solution, start the stopwatch and measure the conductivity of
mixture at different time interval.
Sample taken (measured) at following time intervals.
1, 2, 3 after every 5 seconds
4, 5, 6 for every 10 seconds.
7, 8, 9 for every 15 seconds.
10,11, 12 for every 20 seconds.
13 and onwards for every 30 seconds.
OBSERVATIONS:
Room temperature
Molarity of NaOH
= ________
= ________
Molarity of n-Ethyl Acetate = _____
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OBSERVATION TABLE:
Sr.
Time
conductivity
CA
1/CA
No.
(sec)
Reading (mS)
(gmol/lit)
(gmol/lit)-1
XA
XA/(1- XA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
CA = Concentration of alkali
CB = Concentration of n-Ethyl acetate
CA0, CB0 = Initial Concentration of NaOH and Ethyl acetate respectively.
CALCULATION:
(i) C A  C A0 (1  X A )
GRAPHS:
Draw graphs of calibration curve to find the concentration, CA VS t,
-ln (1-XA) Vs t, (1/CA) Vs t, (XA/ (1- XA)) Vs t
RESULT:
Order of reaction: _________
Rate constant: _________
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CONCLUSION:
Date:
Experiment No:
INTEGRAL METHOD OF ANALYSIS-II
(Non-equimolar Ethyl Acetate –Sodium Hydroxide System)
AIM: To determine the kinetics of reaction between Non-equimolar Ethyl Acetate and
sodium hydroxide at room temperature by the integral method of analysis.
APPARATUS: 500-ml beaker, conductivity meter.
CHEMICALS: Ethyl Acetate, sodium Hydroxide, Distilled water.
THEORY:
In integral method of Analysis the rate of reaction is assumed and based on that
integrated rate expression is obtained. Based on this suitable graph is drawn if straight
line obtained then the assumed order is correct. It is also used to find rate constant at
particular temperature.
NaOH + CH3COOC2H5  CH3COONa + C2H5OH
PROCEDURE:
200 ml of NaOH (0.1 M) is taken in 500-ml beaker, which serves as batch reactor. To
this 200 ml of Ethyl acetate (0.2 M) is added and contents are kept well stirred. After
adding Ethyl acetate, start the stopwatch and measure the conductivity at different time
intervals.
Sample taken (measured) at following time intervals.
1, 2, 3 after every 5 seconds
4, 5, 6 for every 10 seconds.
7, 8, 9 for every 15 seconds.
10,11, 12 for every 20 seconds.
13 and onwards for every 30 seconds.
.
OBSERVATIONS:
Room temperature = ________
Molarity of NaOH = ________
Molarity of Ethyl Acetate = ________
M = CB0/ CA0 = ___
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OBSERVATION TABLE:
Sr.
Time
Conductivity
CA
CB
No.
(sec)
(mS)
(gmol/lit)
(gmol/lit)
ln(CB/MCA)
ln(CB/CA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
CA = Concentration of alkali
CB= Concentration of Ethyl Acetate
CA0, CB0 = Initial Concentration of NaOH and Ethyl acetate respectively.
CALCULATIONS:
GRAPHS: Draw graphs of CA VS t, -ln (1-XA) Vs t, ln (CB/MCA) Vs t, ln (CB/CA) Vs t
RESULT:
Order of reaction: _________
Rate constant: _________
CONCLUSION:
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Date:
Experiment No:
DIFFERANTIAL METHOD OF ANALYSIS
Part 1(Ethyl Acetate –Sodium Hydroxide System)
AIM: To determine the kinetics of reaction between Ethyl Acetate and sodium
hydroxide at room temperature by the differential method of analysis.
APPARATUS: 500-ml beaker, conductivity meter
CHEMICALS: Ethyl Acetate, sodium hydroxide, distilled water.
THEORY:
In the differential method of analysis we test the fit of the rate expression to the data
directly and without any integration. The differential method of analysis deals directly
with the differential rate equation to be tested, evaluating all terms in the equation
including the derivative dCi/dt, and testing the goodness of fit of the equation with
experiment.
NaOH + CH3COOC2H5  CH3COONa + C2H5OH
PROCEDURE:
200 ml of (0.2 M) NaOH is taken in 500 ml beaker, which serves as batch reactor. To this
200 ml of n-Ethyl acetate (0.2 M) is added and contents are kept well stirred. After
adding n-Ethyl acetate, start the stopwatch and measure the conductivity of mixture at
different time interval.
Sample taken (measured) at following time intervals.
1, 2, 3 after every 5 seconds
4, 5, 6 for every 10 seconds.
7, 8, 9 for every 15 seconds.
10,11, 12 for every 20 seconds.
13 and onwards for every 30 seconds.
OBSERVATIONS:
Room temperature
= ________
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Molarity of NaOH
= ________
Molarity of n-Ethyl Acetate = ________
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OBSERVATION TABLE:
CA = Concentration of alkali
CB= Concentration of N-Ethyl Acetate
CA0, CB0 = Initial Concentration of NaOH and Ethyl acetate respectively.
Sr.
Time
Conductivity reading
CA
No.
(sec)
(mS)
(gmol/lit)
1
2
3
4
5
6
7
8
9
10
11
12
GRAPH:
Draw graph of CA vs. t, ln (-rA) vs. ln CA.
CALCULATION:
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From Graph:
Sr.No.
CA
1
2
3
4
RESULT:
1. Order of reaction: _________
2. Rate constant: _________
CONCLUSION:
-rA
ln CA
ln (-rA)
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Date:
Experiment No:
DIFFERANTIAL METHOD OF ANALYSIS
Part 2 (n-Butyl Acetate –Sodium Hydroxide System)
AIM: To determine the kinetics of reaction between n-Butyl Acetate and sodium
hydroxide at room temperature by the differential method of analysis.
APPARATUS: 500-ml beaker, conductivity meter.
CHEMICALS: n-Butyl Acetate, sodium hydroxide, distilled water.
THEORY:
In the differential method of analysis we test the fit of the rate expression to the data
directly and without any integration. The differential method of analysis deals directly
with the differential rate equation to be tested, evaluating all terms in the equation
including the derivative dCi/dt, and testing the goodness of fit of the equation with
experiment.
NaOH + CH3COOC4H9  CH3COONa + C4H9OH
PROCEDURE:
200 ml of (0.05 M) NaOH is taken in 500 ml beaker, which serves as batch reactor. To
this 200 ml of n-Butyl acetate (0.1 M) is added and contents are kept well stirred. After
adding n-Butyl acetate, start the stopwatch and measure the conductivity of mixture at
different time interval.
Sample taken (measured) at following time intervals.
1, 2, 3 after every 5 seconds
4, 5, 6 for every 10 seconds.
7, 8, 9 for every 15 seconds.
10,11, 12 for every 20 seconds.
13 and onwards for every 30 seconds.
OBSERVATIONS:
Room temperature
= ________
Molarity of NaOH
= ________
Molarity of n-Butyl Acetate = ________
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OBSERVATION TABLE:
CA = Concentration of alkali
CB= Concentration of n-Butyl Acetate
CA0 ,CB0 = Initial Concentration of NaOH and Butyl acetate respectively.
Sr.
Time
Conductivity reading
CA
No.
(sec)
(mS)
(gmol/lit)
1
2
3
4
5
6
7
8
9
10
11
12
GRAPH:
Draw graph of CA vs t, ln (-rA) vs ln CA.
CALCULATION:
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From Graph:
Sr.No.
CA
1
2
3
4
RESULT:
1. Order of reaction: _________
2. Rate constant: _________
CONCLUSION:
-rA
ln CA
ln (-rA)
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Date:
Experiment No:
ACTIVATION ENERGY AND FREQUENCY FACTOR
Part 1 (Ethyl Acetate –Sodium Hydroxide System)
AIM: To determine the activation energy and frequency factor for the reaction between
Ethyl acetate and sodium hydroxide.
APPARATUS: 500-ml beaker, conductivity meter
CHEMICALS: Ethyl Acetate, sodium hydroxide, distilled water.
THEORY:
The rate constant of the reaction is a function of activation energy of the reaction under
consideration and temperature. Arrhenius theory is mostly valid for all reactions.
K=K0 e –(E/RT)
Where K= Rate constant
K0 = Frequency factor
E= Activation Energy
R= Gas constant
T= Absolute temperature.
Initially experiment conducted at different temperature and the value of K is determine
then it is an easy to evaluate value of frequency factor.
PROCEDURE:
Initially experiment is conducted at room temperature; 100 ml of 0.1N NaOH is added in
the beaker, which serves as a batch reactor. In this 100 ml of 0.2M n-Ethyl Acetate is
added and contents are kept well stirred. Start stopwatch and at every 10 sec measure the
conductivity of sample. The experiment again repeated for 40C, 50C and 60C
.
OBSERVATIONS:
Room temperature = ________
Molarity of NaOH= ________
Molarity of n-Ethyl Acetate = _____
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OBSERVATION TABLE:
SET -- I (Room Temperature)
Sr.No.
Time
Conductivity
CA
(sec)
reading
(gmol/lit)
CB
ln(CB/MCA)
1
2
3
4
5
SET -- II (At 40 C Temperature)
Sr.No.
1
2
3
4
5
Time
Conductivity
CA
(sec)
reading(mS)
(gmol/lit)
CB
ln(CB/MCA)
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SET – III (At 50 C Temperatures)
Sr.No.
Time
Conductivity
CA
(sec)
reading(mS)
(gmol/lit)
CB
ln(CB/MCA)
CB
ln(CB/MCA)
1
2
3
4
5
SET – IV (At 60 C Temperatures)
Sr.No.
Time
Conductivity
CA
(sec)
reading(mS)
(gmol/lit)
1
2
3
4
5
CALCULATION:
CA = Concentration of alkali
CB = Concentration of n-Ethyl acetate
CA0,CB0 = Initial Concentration of NaOH and Ethyl acetate respectively.
GRAPHS:
1. Draw graph of ln (CB/MCA) Vs Time. (Room temperature, 40oC, 50oC, 60oC)
From Slope find = k1, k2, k3 , k4
2. Draw graph of lnk Vs 1/T
Slope of this graph is –E/R
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Rate
Sr.No.
Constant
lnk
k
1
2
3
4
RESULT:
1.Frequency factor k0 = __________
2.Activation energy E = __________
CONCLUSION:
Avg. Temp.
T(K)
1/T
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Date:
Experiment No:
ACTIVATION ENERGY AND FREQUENCY FACTOR
Part 2(n-Butyl Acetate –Sodium Hydroxide System)
AIM: To determine the activation energy and frequency factor for the reaction between
n-Butyl Acetate and sodium Hydroxide.
APPARATUS: 500-ml beaker, conductivity meter.
CHEMICALS: n-Butyl Acetate, sodium Hydroxide, distilled water.
THEORY:
The rate constant of the reaction is a function of activation energy of the reaction under
consideration and temperature. Arhenius theory is mostly valid for all reactions.
K=K0 e –(E/RT)
Where K= Rate constant
K0= Frequency factor
E= Activation Energy
R= Gas constant
T= Absolute temperature.
Initially experiment conducted at different temperature and the value of K is determine
then it is an easy to evaluate value of frequency factor.
PROCEDURE:
Initially experiment is conducted at room temperature; 100 ml of 0.1M NaOH is added in
the beaker, which serves as a batch reactor. In this 100 ml of 0.1M n-Butyl Acetate is
added and contents are kept well stirred. Start stopwatch and at every 10 sec measure the
conductivity of sample. The experiment again repeated for 40C, 50C and 60C
.
OBSERVATIONS:
Room temperature = ________
Molarity of NaOH= ________
Molarity of n-Butyl Acetate = _____
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OBSERVATION TABLE:
SET – I (Room Temperature)
Sr.No.
Time
(sec)
Conductivity
reading (mS)
CA
(gmol/lit)
CB
1/CA
(gmol/lit)-1
CA
(gmol/lit)
CB
1/CA
(gmol/lit)-1
1
2
3
4
5
SET -- II (At 40 C Temperature)
Sr.No.
Time
(sec)
Conductivity
reading (mS)
1
2
3
4
5
SET - III (At 50 C Temperature)
Sr.No.
1
2
3
4
5
Time
(sec)
Conductivity
reading (mS)
CA
(gmol/lit)
CB
1/CA
(gmol/lit)-1
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SET – IV (At 60 C Temperatures)
Time
Sr.No.
(sec)
Conductivity
reading (mS)
CA
(gmol/lit)
CB
1/CA
(gmol/lit)-1
1
2
3
4
5
CA = Concentration of alkali
CB = Concentration of n-Butyl acetate
CA0, CB0 = Initial Concentration of NaOH and Ethyl acetate respectively.
CALCULATION:
GRAPHS:
1.
Draw graph of (1/CA) Vs Time (Room temperature, 40oC, 50oC,60oC)
From Slope find = k1, k2, k3, k4
2.
Draw graph of lnk Vs 1/T
Slope of this graph is –E/R
Sr.No.
Rate
Constant
k
lnk
1
2
3
4
RESULT:
1.Frequency factor K0 = __________
2.Activation energy E = __________
CONCLUSION:
Avg. Temp. T
(K)
1/T
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Date:
Experiment No:
KINETICS BY HALF LIFE PERIOD
(Ethyl Acetate –Sodium Hydroxide System)
AIM: To determine the characteristics of reaction between Ethyl acetate and sodium
hydroxide at room temperature by the method of half-life period.
APPARATUS: 500 mL beaker, conductivity meter.
CHEMICALS: Ethyl Acetate, sodium hydroxide, distilled water.
THEORY:
Half-life indicates the time required for the concentration of reactants to reach the half of
its initial value. It is essential that the reactants be taken in stoichiometric proportion.
From the data of CA  t, it is possible to obtain kinetics by simple manner.
PROCEDURE:
150 ml of (0.1 M) NaOH is taken in 500 ml beaker, which serves as batch reactor. To this
150 ml of n-Ethyl acetate (0.1 M) is added and contents are kept well stirred. After
adding n-Ethyl acetate, start the stopwatch and measure the conductivity of mixture at
different time interval.
Sample taken (measured) at following time intervals.
1, 2, 3 after every 5 seconds
4, 5, 6 for every 10 seconds.
7, 8, 9 for every 15 seconds.
10,11, 12 for every 20 seconds.
13 and onwards for every 30 seconds.
Repeat the same procedure for different equimolar initial concentrations of NaOH and nEthyl acetate.
OBSERVATIONS:
Room temperature
= ________
Molarity of NaOH
= ________
Molality of n-Ethyl Acetate = ________
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OBSERVATION TABLE:
Sr.
Time
Conductivity reading
CA
No.
(sec)
(mS)
(gmol/lit)
1
2
3
4
5
6
7
8
9
10
11
12
Sr.No.
CA0
t1/2
ln t1/2
ln CA0
1
2
3
4
5
6
GRAPH:
If we plot ln t ½  ln CA0 ,it will give a straight line, from the slope and
intercept we can calculate order of a reaction and specific rate constant k.
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CALCULATION:
Half-life period for any reaction can be calculated by the following equation:
Slope = m = (1-n) = ------------------Order of reaction = -------------------Intercept = ---------------Rate constant, k = ----------RESULT: Order of reaction = -------------------Rate constant = -----------
CONCLUSION:
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Date:
Experiment No:
PSEUDO FIRST ORDER REACTION
(Ethyl Acetate –Sodium Hydroxide System)
AIM: To study the kinetics of pseudo order reaction between Ethyl acetate and sodium
hydroxide in a constant volume batch reactor.
APPARATUS: 500 mL beaker, measuring cylinder, stirrer, stop watch, sample bottles,
conductivity meter.
CHEMICALS: Ethyl Acetate, sodium hydroxide, distilled water.
PROCEDURE:
1. The standardized 0.025M NaOH is taken in quantity of 150 ml.
2. The 150 ml of 2M Ethyl Acetate is taken in another beaker.
3. Mixture of Ethyl acetate and NaOH are taken in a batch reactor and
continuous stirring is done. Measure the conductivity of reaction mixture at
different time intervals.
OBSERVATIONS:
Room temperature
= ________
Molarity of NaOH
= ________
Molarity of n-Ethyl Acetate = ________
OBSERVATION TABLE:
Sr.No.
1
2
3
4
5
6
Time
Conductivity reading
CA
(sec)
(mS)
(gmol/L)
-ln CA /CA 0
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CALCULATION:
RESULT:
CONCLUSION:
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Date:
Experiment No:
TO STUDY ABOUT PLUG FLOW REACTOR
(Ethyl Acetate –Sodium Hydroxide System)
AIM: To study the kinetics of reaction between ethyl acetate and sodium hydroxide in a
PFR.
APPARATUS: Tubular reactor, measuring cylinder, sample bottles, storage tanks,
stopwatch, conductivity meter.
CHEMICALS: Ethyl Acetate, sodium hydroxide, water.
ASSUMPTIONS:
1. The liquid through the reaction has constant density and its flow is in
steady state.
2. There is no back mixing.
PROCEDURE:
1. Set the practical instrument.
2. Fill the tank with the chemicals (0.1M Ethyl acetate & 0.1M NaOH).
3. Keep the flow rate constant.
4. Measure the flow rate, take sample at outlet and measure conductivity of
solution.
5. Get the readings for different flow rates.
OBSERVATIONS:
Room temperature
= ________
Molarity of NaOH
= ________
Molarity of n-Ethyl Acetate = ________
OBSERVATION TABLE:
Flowrate
Sr.No.
(LPM)
1
2
3
4
Conductivity
(mS)
CA
1/ CA
t=V/V0
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5
6
CALCULATION:
GRAPH:
RESULT:
CONCLUSION:
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Date:
Experiment No:
TO STUDY ABOUT CONTINUOUS STIRRED TANK REACTOR
(Ethyl Acetate –Sodium Hydroxide System)
AIM: To study the kinetics of reaction between ethyl acetate and sodium hydroxide in
CSTR.
APPARATUS: Measuring Cylinder, Stirrer, Stopwatch, Sample bottles, storage tanks.
CHEMICALS: Ethyl Acetate, sodium Hydroxide, water.
PROCEDURE:
1.
2.
3.
4.
5.
Set the practical instrument.
Fill the tank with the chemicals (0.1M Ethyl acetate & 0.1M NaOH).
Keep the flow rate constant.
Measure the flow rate, take sample at outlet and measure conductivity of solution.
Get the readings, which would show readings at different flow rates.
OBSERVATIONS:
Room temperature
= ________
Molarity of NaOH
= ________
Molarity of n-Ethyl Acetate = ________
OBSERVATION TABLE:
Sr.No.
1
2
3
4
Flowrate
Conductivity
(LPM)
(mS)
CA
1/ CA
t=V/V0
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5
6
CALCULATION:
GRAPH:
RESULT:
CONCLUSION:
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Date:
Experiment No:
CSTR of Different size in Series
AIM: To determine the best system for a known kinetics of ethyl acetate and sodium
hydroxide in two different mixed flow reactors in series and compare the results.
1) Larger CSTR (2.5 L) followed by Smaller CSTR (1 L)
2) Smaller CSTR (1 L) followed by Larger CSTR (2.5 L)
CHEMICALS: NaOH, ethyl acetate, water.
APPARATUS: Two overhead tanks, larger CSTR (2.5 L), smaller CSTR (1 L),
conductivity meter, magnetic stirrer, measuring cylinders
THEORY:
Given –rA as a function of conversion, –rA = f(X), one can also design any sequence of
reactors in series provided there are no side streams by defining the overall conversion at
any point.
Mole Balance on Reactor 1
Mole Balance on Reactor 2
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Experimental Setup:
Case 1 - Larger volume CSTR followed by lesser volume CSTR
 Overhead tanks are set at an equal height as shown in figure.
 The opening of the valve of the tanks is such that equal flow rate is attained from both
the tanks.
 The outlets from both the overhead tanks are kept in a larger volume CSTR
 The outlet of larger volume CSTR is kept in a lesser volume CSTR.
 The outlet of lesser volume CSTR is kept in a separate vessel to collect the overflow
material of the latter CSTR and take the readings.
Case 2 - Lesser volume CSTR followed by larger volume CSTR
 Overhead tanks are set at an equal height as shown in figure.
 The opening of the valve of the tanks is such that equal flow rate is attained from
both the tanks.
 The outlets from both the overhead tanks are kept in a lesser volume CSTR The
outlet of lesser volume CSTR is kept in a larger volume CSTR.
 The outlet of larger volume CSTR is kept in a separate vessel to collect the overflow
material of the latter CSTR and take the readings.
Procedure:
Case 1 - Larger volume CSTR followed by lesser volume CSTR
1. Maintain a constant flow rate of both, 0.1 M NaOH and 0.1 M ethyl acetate into larger
CSTR by overhead tanks.
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2. Measure conductivity of mixture in both CSTRs simultaneously when lesser volume
CSTR starts overflowing.
3. Use calibration graph (or calibration equation) to convert conductivity into
concentration.
4. To find out conversion use equation CA=CA0(1-XA).
5. Repeat the same procedure for case 2 where smaller size of CSTR followed by larger
one.
OBSERVATIONS:
Concentration of NaOH solution:
Concentration of ethyl acetate solution:
Case 1 - Larger volume CSTR followed by lesser volume CSTR
CSTR
Conductivity
Concentration
Larger volume CSTR
Lesser volume CSTR
Case 2 - Lesser volume CSTR followed by larger volume CSTR
CSTR
Conductivity
Concentration
Larger volume CSTR
Lesser volume CSTR
CALCULATIONS:
Case 1 - Larger volume CSTR followed by lesser volume CSTR
CA=CA0 (1-XA)
CA: Concentration of the overflow material out of the lesser volume CSTR after steady
state is attained.
CA0: Concentration of NaOH at time t=0
Case 2 - Lesser volume CSTR followed by larger volume CSTR
CA=CA0 (1-XA)
CA: Concentration of the overflow material out of the larger volume CSTR after steady
state is attained.
CA0: Concentration of NaOH at time t=0
GRAPHS:
RESULT:
CONCLUSION:
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Date:
Experiment No:
To study about CSTR and PFR in Series
(Ethyl Acetate-NaOH system)
AIM: To study the kinetics of reaction between Ethyl Acetate and NaOH at room temp
for the following different cases of series combinations of CSTR and PFR.
APPARATUS: CSTR, PFR, Conductivity meter.
CHEMICALS: Ethyl Acetate, NaOH, Phenolphthalein.
THEORY :
If reactors of different types are put in series, such as a mixed flow reactor followed by a
plug flow reactor we may write :
CASE I: CSTR followed by a PFR.
CASE II: PFR followed by a CSTR.
If these relationships are represented in graphical form it allows us to predict the overall
conversions for such systems, or conversions at intermediate points between the
individual reactors.
Many times, reactors are connected in series so that the exit stream of one reactor is the
feed stream for another reactor. When this arrangement is used, it is often possible to
speed calculations by defining conversion in terms of location at a point downstream
rather than with respect to any single reactor. That is, the conversion X is the total
number of moles of A that have reacted up to that point per mole of A fed to the first
reactor. For reactors in series
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However, this definition can only be used when the feed stream only enters the first
reactor in the series and there are no side streams either fed or withdrawn. The molar
flow rate of A at point i is equal to moles of A fed to the first reactor minus all the moles
of A reacted up to point i:
Best Arrangement of a Set of Ideal Reactors.
For the most effective use of a given set of ideal reactors we have the following general
rules:
1. For a reaction whose rate-concentration curve rises monotonically (Nth-order reaction,
n > 0) the reactors should be connected in series. They should be ordered so as to keep
the concentration of reactant as high as possible if the rate-concentration curve is concave
(n > I), and as low as possible if the curve is convex (n < 1). As an example, for the case
of Fig. above the ordering of units should be plug, small mixed, large mixed, for n > 1;
the reverse order should be used when n < 1.
2. For reactions where the rate-concentration curve passes through a maximum or
minimum the arrangement of units depends on the actual shape of curve, the conversion
level desired, and the units available. No simple rules can be suggested.
3. Whatever may be the kinetics and the reactor system, an examination of the l/(-rA,) vs.
CA curve is a good way to find the best arrangement of units.
PROCEDURE:
 In these practical we will interchange the positions of the CSTR and PFR and
perform the experiment.
 A ‘T’ joint will be provided at intervals to insert and measure the conductivity of
the flow by a conductivity meter.
 200 ml of 0.1 M Ethyl Acetate is taken in 500 ml beaker. To this 200 ml of 0.1 M
NaOH is added.
 This mixture is then passed through the series of reactors. Conductivity is
measured at different points at a specified interval of time.
 The conductivity is measured till it becomes constant with time.
 A graph of Conductivity v/s Concentration gives us the respective concentration.
The final conversion is then calculated from these final and initial concentrations.
OBSERVATIONS:
1. Room Temperature =
2. Molarity of NaOH =
3. Molalrity of Ethyl Acetate =
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OBSERVATION TABLE:
CASE I: CSTR followed by a PFR.
Sr. No.
Conductivity Concentration
(mS)
(gmol/L)
1
2
3
CASE II: PFR followed by a CSTR.
Sr. No.
Conductivity Concentration
(mS)
(gmol/L)
1
2
3
RESULT:
% Conversion = CA0-CA / CA0
CASE
I
II
CONCLUSION:
Initial Conc.(CA0)
Final Conc.(CA)
Conversion (%) XA
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Date:
Experiment No:
To study about CSTR in Series
(Ethyl Acetate-NaOH system)
AIM: To study the kinetics of Ethyl Acetate and NaOH at room temperature in equal
size of three CSTR in series and compare the performance with the single CSTR of
same volume.
APPARATUS: 3 CSTR (Vol = 450 ml), 1 CSTR (Vol = 1350 ml), Conductivity meter.
CHEMICALS: Ethyl Acetate, NaOH, water.
THEORY:
Equal-Size Mixed Flow Reactors in Series
In plug flow, the concentration of reactant decreases progressively through the system; in
mixed flow, the concentration drops immediately to a low value. Because of this fact, a
plug flow reactor is more efficient than a mixed flow reactor for reactions whose rates
increase with reactant concentration, such as nth-order irreversible reactions, n >
0.Consider a system of N mixed flow reactors connected in series. Though the
concentration is uniform in each reactor, there is, nevertheless, a change in concentration
as fluid moves from reactor to reactor. This stepwise drop in concentration is illustrated
in Fig below.
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It suggests that the larger the number of units in series, the closer should the behaviour of
the system approach plug flow. This will be shown be to so. Let us now quantitatively
evaluate the behavior of a series of N equal-size mixed flow reactors. Density changes
will be assumed to be negligible; hence E = 0 and t = 7. As a rule, with mixed flow
reactors it is more convenient to develop the necessary equations in terms of
concentrations rather than fractional conversions; therefore, we use this approach. The
nomenclature used is shown
in Fig. below with subscript i referring to the ith vessel.
First-Order Reactions: From Eq. Below, a material balance for component about vessel i
give
Because E = 0 this may be written in terms of concentrations. Hence
Or
Now the space-time r (or mean residence time t) is the same in all the equalize reactors of
volume Vi. Therefore,
Rearranging, we find for the system as a whole
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In the limit, for N + m, this equation reduces to the plug flow equation
With this last equation we can compare performance of N reactors in series with a plug
flow reactor or with a single mixed flow reactor. This comparison is shown in Fig. below
for first-order reactions in which density variations are negligible.
PROCEDURE:
 In first case we will use only a single CSTR and measure the conversion in the
system for a given case of Ethyl-Acetate and NaOH.
 In second case we will take three equal size of CSTR in series whose total volume
is equal to that of the volume of the single CSTR in the previous case and
maintain the same flow rate in both the cases.
 200 ml of Ethyl Acetate (0.1 M) is taken in 500 ml beaker. To this 200 ml of (0.1
M) NaOH is added. This mixture is then passed through the series of reactors.
Conductivity is measured at different points at a specified interval of time.
 Once the steady state is achieved the conductivity of individual CSTR is
measured.
 A graph of Conductivity v/s Concentration gives us the respective concentration.
The final conversion is then calculated from these final and initial concentrations.
OBSERVATIONS:
1. Room Temperature =
2. Molarity of NaOH = 0.1M.
3. Molarity of Ethyl Acetate =0.1M.
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4.
5.
6.
7.
8.
Flow rate=
Experimental volume of single CSTR= 1350 ml
Experimental volume of single small CSTR= 450 ml.
Total time duration in Case I (Single CSTR) =
Total time duration in Case II (3 CSTR in series) =
OBSERVATION TABLE:
Case I: Single CSTR
Sr. No.
Conductivity Concentration
(mS)
(gmol/L)
Initial
Final
Case II: Three CSTR in series
Stage
Conductivity Concentration
(mS)
(gmol/L)
1
2
3
CALCULATIONS:
CASE
I
II
RESULT:
CONCLUSION:
Initial Conc.(CA0)
Final Conc.(CA)
Conversion (%) XA
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