1.0 ABSTRACT The conduction of this experiment is based on a few targets, namely to carry out saponification reaction between Sodium Hydroxide, NaOH and Ethyl Acetate, Et(AC), to determine the effect of residence time to the reaction's extent of conversion and lastly to evaluate the reaction rate constant of this particular saponification reaction. To achieve these targets, an experiment is finely designed so much so that these targets can be finely met. Such experiment involves using a unit called SOLTEQ Plug Flow Reactor (Model: BP 101), commonly known as PFR, as well as some common laboratory apparatus for titration process. To put it simply, the two solutions Sodium Hydroxide, NaOH and Ethyl Acetate, Et(Ac) were reacted in the PFR and the product is then analyses by the method of titration to determine how well did the reaction go. Hence, the experiment was conducted and the result shows that the amount of conversion of Sodium Hydroxide, NaOH is almost unchanged as residence time increases. Further details can be obtained in the results and discussion sections.

2.0 INTRODUCTIONType of chemical reactors remains a highly discussed subject in chemical process industries worldwide. The reactor is of course, the place where chemical reactions take place. Hence it is arguably the single most important part of any chemical process design. The design of a reactor must be finely tuned so that its mechanisms suit the necessities of the process that is to be carried. Depends on the nature of the materials in both the feed and of course the products, the reactors may take a wide range of forms. This is why full comprehension of a reactor of a particular design as well as its working mechanisms is very much vital to actually conduct a particular chemical process.

In this experiment, the Plug Flow Reactor (Model: BP101) is used as it has been properly designed for students' experiment on chemical reactions in liquid phase under isothermal and adiabatic conditions. Included in the unit is a jacketed plug flow reactor; individual reactant feed tanks and pumps, temperature sensors and conductivity measuring sensor. By using this particular unit, students will be capable to conduct the typical saponification reaction between ethyl acetate and sodium hydroxide among the others reaction.3.0OBJECTIVE

I. To study the saponification reaction of ethyl acetate, Et (Ac) and sodium hydroxide, NaOH.II. To determine the reaction rate constant.

4.0THEORYIn a tubular reactor, the feed enters at one end of a cylindrical tube and the product stream leaves at the other end. The long tube and the lack of provision for stirring prevent complete mixing of the fluid in the tube. Hence the properties of the flowing stream will vary from one point to another, namely in both radial and axial directions.

In the ideal tubular reactor, which is called the plug flow reactor, specific assumptions are made about the extent of mixing: 1. No mixing in the axial direction, i.e., the direction of flow 2. Complete mixing in the radial direction 3. A uniform velocity profile across the radius.

The absence of longitudinal mixing is the special characteristics of this type of reactor. It is an assumption at the opposite extreme from the complete mixing assumption of the ideal stirred tank reactor. The validity of the assumptions will depend on the geometry of the reactor and the flow conditions. Deviations, which are frequent but not always important, are of two kinds: 1. Mixing in longitudinal direction due to vortices and turbulence 2. Incomplete mixing in radial direction in laminar flow conditions Mass Balance For a time element t and a volume element V, the mass balance for species i is given by the following equation: QA CA v t- QA CAv+v t - rAVt = 0 (10.1.1)

Where QA : molar feed rate of reactant A to the reactor, mol/sec CA: concentration of reactant A rA : rate of disappearance of reactant A, mol/ltsec The conversion, X, is defined as: X = (initial concentration - final concentration) / (initial concentration) Since the system is at steady state, the accumulation term in Equation (10.1.1) is zero. Equation (10.1.1) can be written as: -QA CA - rAV = 0 (10.1.2)

Dividing by V and taking limit as V 0

dCA/dV = -rA/QA (10.1.3) This is the relationship between concentration and size of reactor for the plug flow reactor. Here rate is a variable, but varies with longitudinal position (volume in the reactor, rather than with time). Integrating, -dV/ QA = dCA/rA (10.1.4) At the entrance: V = 0 CA = CA0At the exit: V = VR (total reactor volume)

CA = CA (exit conversion)

5.0APPARATUS AND MATERIALThe unit used in this experiment is SOLTEQ Plug Flow Reactor (Model: BP101).

Plug Flow Reactor is used as it has been properly designed for students experiment on the chemical reactions in liquid phase under isothermal and adiabatic conditions, temperature sensors and conductivity measuring sensor.

Apart from that, there were also same laboratory apparatus involved such as; Burette Conical flask Measuring cylinder Beakers

Among the chemicals used are; 0.1M Sodium Hydroxide, NaOH 0.1M Ethyl Acetate, Et(Ac) 0.25M Hydrochloric acid, HCl Deionised water pH indicator, Phenolphthalein

6.0PROCEDUREGeneral start-up procedures1. All the valves are ensured closed except V4, V8 and V17.2. The following solutions are prepared: 20 litre of NaOH (0.1M) 20 litre of Et(Ac) (0.1M)1 litre of HCL (0.25M) for quenching3. Feed tank B1 was filled with NaOH while feed tank B2 was filled with the Et(Ac).4. The water jacket B4 was filled with water and pre-heater B5 was filled with clean water.5. The power for the control panel was turned on.6. Valves V2, V4, V6, V8,V9 and V11 were opened.7. Both pumps P1 and P2 were switched on. P1 and P2 were adjusted to obtained flow rate approximately 300mL/min at both flow meters Fl-01 and Fl-02. Both flow rates were made sure to be equal.8. Both solutions then were allowed to flow through the reactor R1 and overflow into waste tank B3.9. Valves V13 and V18 was opened. Pump P3 then was switched on in order to circulate the water through pre-heater B5. The stirrer motor M1 was switched on and set up to speed about200 rpm to ensure homogeneous water jacket temperature.

Experiment Procedures1. The general starts up procedures were performed.2. Valves V9 and V11 wereopened.3. Both the NaOH and Et (Ac) solutions were allowed to enter the plug reactor R1 and empty into the waste tank B3.4. P1 and P2 were adjusted to give a constant flow rate ofabout 300 ml/min at flow metersFI-01 and FI-02. Both flow rates were ensured same. The flow rates were recorded.5. The inlet (QI-01) and outlet (QI-02) were started to monitor the conductivity values until they do not change over time. This is to ensure that thereactor has reached steady state.6. Both inlet and outlet steady state conductivity values were recorded. The concentration ofNaOH exiting the reactor and extent of conversion from the calibration curve.7. Optional. Sampling was opened from valve V15 and 50ml of sample was collected. A backtitration procedure was carried out manually to determine the concentration of NaOH in the reactor and extent of conversion.8. The experiment was repeated from step 4 to7 for different residence timesby reducing the feed flow ratesof NaOH and Et(Ac)to about 250,200,150,100 and 50 ml/min. Both flow rates were made sure to be equal.

Back Titration Procedures

1. The burette was filled up with 0.1 M NaOH solution.2. 10 mL of 0.25 M HCl was poured in a flask.3. 50 mL samples that were collected from theexperiment at every controlled flow rate(300,250, 200, 150, 100 and 50 mL/min) were added intothe 10mL HCl to quench the saponification reaction.4. 3 drops of phenolphthalein were dropped into the mixture of sample and HCl.5. The mixture then was titrated with NaOH until it turns light pink.6. The amount of NaOH titrated was recorded.

7.0 RESULTReactor Volume : 4 LConcentration of NaOH in the reactor, CNaOH : 0.1M (2L)Concentration of NaOH in the feed vessel, CNaOH,f : 0.1M (2L)Concentration of HCl quench, CHCl,s : 0.25M (0.01L)Volume of sample, Vs : 0.05LTable 1Flow rate of NaOH (mL/min)Flow rate of Et(Ac) (mL/min)Residence Time, (min)Outlet ConductivityVolume of NaOH

Q1Q2

30030056.85.519.9

25025056.85.319.4

20020056.75.220.2

15015057.45.224.1

100100575.318.8

Table 2Residence Time, (min)ConversionX, (%)Reaction Rate constant, k (L.mol/min)Rate of Reaction, -rA (mol.L/min)

6.666789.813.2060.00137

888.89.91070.00124

1090.49.4170.00087

13.333398.240.9170.00013

2087.63.5320.00054

SAMPLE OF CALCULATIONResidence timeFor flow rates of 300 ml/min : Residence time, = Reactor volume (L), VTotal flow rate (L/min), V0Total flow rate, V0 = Flow rate of NaOH + Flow rate of Et(Ac)= 300 mL/min NaOH + 300 mL/min Et(Ac)= 600 mL/min=0.6 L/minHence,Residence time, = 4L= 6.6667 min (This value is placed on the Table 2)0.6 L/minWith the difference flow rate, the other residence time is calculated exactly the same way as stated above.

ConversionFor flow rates of 300 mL/min :Moles of reacted NaOH, n1n1 = Concentration NaOH x Volume of NaOH titrated=0.1 M x 0.0199 L=0.00199 moleMoles of unreacted HCl, n2n2= Moles of reacted NaOHn2= n1n2= 0.00199 moleVolume of unreacted HCl, V1V1= n2 Concentration HCl quench= 0.001990.25= 0.00796 LVolume of HCl reacted, V2V2= Total volume HCl- V1=0.01 0.00796= 0.00204 LMoles of reacted HCl, n3n3= Concentration HCl x V2=0.25 x 0.00204= 0.00051 moleMoles of unreacted NaOH, n4n4= n3= 0.00051 moleConcentration of unreacted NaOHCNaOH=n4volume sample= 0.00051 0.05= 0.0102 MXunreacted= Concentration of NaOH unreacted concentration NaOH= 0.0102 0.1=0.102 Xreacted = 1 - Xunreacted= 1 0.102= 0.898Conversion for flow rate 300mL/min0.898 x 100% = 89.8% (This value is then placed in Table 2)Thus, at flow rate 300mL/min of NaOH in the reactor, 89.8% of NaOH is reacted with Et(Ac). With the different flow rates, the other conversions were calculated in the same manner.

Reaction Rate Constant, k

Whereby for flow rates 300 mL/min:V0 = Total inlet flow rate =0.6 L/minVTFR= Volume for reactor=4 LCAO= inlet concentration of NaOH=0.1X= 0.898k= 0.6(0.898 / 1-0.898)= 13.206 L.mol/min (Placed in Table 2)(4)(0.1)With different flow rates, other reaction rate constants were calculated in the same manner.

Rate of Reaction, -rA-rA= k (CAO)2 (1 X)2For flow rates of 300 mL/min :-rA= 13.206 (0.1)2(1- 0.898)2=0.00137 mol.L/min (this value is inserted in Table 2)With different flow rate, the others rate of reaction were calculated in the same manner.

8.0DICUSSIONBased on the experiment that had been conducted, the conductivity of the process reached stability when the flow rate of NaOH and the flow rate of Et(Ac) increased. The reaction in the vessel then separately in three vessel where the contain of the NaOH in the neutralized water were bypass and the comparison between vessel 1 and vessel 2 was determined. The flow rate for both at 150 and 200 reached equilibrium because of the ion transfer due to conduction where the actual process of the acid base transferring ion to the water. The quality of sample titrated to measured the volume of NaOH where the conversion of the sample determine.

9.0CONCLUSIONAs a conclusion, the experiments are successful as all the objectives are achieved. It can be concluded that the feed flow rates affects the rate of reaction, reaction rate constant and the percentage of conversion. As the flow rates are decrease, the rate of reaction will decrease and the percentage of the conversion increase. The longer residence times in the reactor, the greater the conversion of NaOH. Finally, as the feed flow rate decreases, the volume of NaOH titrated to neutralize the sample will increase.

10.0RECOMMENDATION1. The column needs further rinsing with deionised water to remove excess hydrogen ions from the column2. The titration process must be conducted carefully to obtain the required pink pale of titration process of acid and base.3. Always wear protective clothing, shoes, helmet and goggles throughout the laboratory session.4. Always run the experiment after fully understand the unit and procedures.

11.0REFERENCES1. Boles, M. A. and Y. A. Gengel, Thermodynamics, Engineering Approach , 7th ed., McGraw Hill Book Company, St. Louis, MO, 2011, p. 8-12.

2. Harriot, P., W. L. McCabe, and J. C. Smith, Unit Operations of Chemical Engineering, 7th ed., McGraw-Hill Book Company, St. Louis, MO, 2011, p. 330-340.

3. Occupational Safety and Health Standards for Genreal Industry, 29CFR Part 1910.303, 1994.

4. AdiChemistry [Online] Available from http://www.adichemistry.com/physical/kinetics/factors/factors-affecting-rate-reaction.html

5. Enzyme Technology [Online] Available from http://www.lsbu.ac.uk/water/enztech/cstr.html Accessed on 26th April 2013

6. Kinetic Supplement [Online] Available from http://www.usm.edu/polymerkinetics/genkin.pdf . Accessed on 23rd April 2013

7. Reaction law, Reaction Rates and Activation Energy [Online] Available from http://www.csun.edu/chem/documents/Kinetics.pdf. Accessed on 25th April 201312.0APPENDIX

2