1.0 Results

Experiment 3 : Effect of Residence Time on the Reaction

No.

Flow rate

of NaOH

(mL/min)

Flow rate

of Et(Ac)

(mL/min)

Total flow

rate of

solutions,

Vo

(mL/min)

Residence

time, τ

(min)

Outlet

conductivity

(mS/cm)

Conversion,

X (%)

Reaction

Rate

Constant

(L/mol.min)

Rate of

Reaction,

(mol/L.min)

1 300 300 600 6.67 6.6 86.8 19.7273 8.5932 X 10-4

2 250 250 500 8.00 6.7 72.8 8.0294 1.4851 x 10-3

3 200 200 400 10.00 6.7 58.8 4.2816 1.8169 x 10-3

4 150 150 300 13.33 5.7 79.00 11.2857 1.2443 X 10-3

5 100 100 200 20.00 4.8 93.8 45.3871 4.3617 X 10-4

6 50 50 100 40.00 4.6 83.2 14.857 1.0483 X 10-3

2.0 Calculations

Total flowrate solution = 600 ml/min

Reactor volume : 4 L

Volume of sample, Vs : 0.05 L

Concentration of NaOH in feed vessel, CNAOH, f : 0.1 mol/L

Concentration of ethyl acetate in feed vessel, CEA,O : 0.1 mol/L

Volume of HCl for quenching, VHCl, s : 10 ml

Concentration of HCl in standard solution, CHCL, S : 0.25 mol/L

Volume of titrated NaOH, V1 : 21.7 ml

Concentration of NaOH used for titration, CNaOH,s : 0.1 mol/L

1. Concentration of NaOH entering reactor, CNaOH, o = (CNaOH, f) ÷ 2

0.1 mol/L ÷ 2 = 0.05 mol/L

2. Volume of unreacted quenching HCl, V2 = (CNaOH,s ÷ CHCl,s) × V1

(0.1 mol/L ÷ 0.25 mol/L) × 21.7 ml = 8.68 ml

3. Volume of HCl reacted with NaOH in sample, V3 = VHCl,s – V2

10 ml – 8.68 ml = 1.32 ml / 0.0013 L

4. Moles of HCl reacted with NaOH in sample, n1 = CHCl,s × V3

0.25 mol/L × 0.0013 L = 0.00033 mol

5. Moles of unreacted NaOH in sample, n2 = n1

n2 = 0.00033 mol

6. Concentration of unreacted NaOH in reactor, CA = n2 ÷ VS

0.00033 mol ÷ 0.05 L = 0.0066 mol/L

7. Conversion of NaOH in reactor, X = (1 – (CNaOH ÷ CNaOH,O)) × 100%

(1 – (0.0066 mol/L ÷ 0.05 mol/L) ) × 100% = 86.8 %

8. Residence time, τ=V TFR

V 04000 ml ÷ 600 ml/min = 6.67 min

9. Reaction rate constant, k=V o

V TFRCAO[ X1−X ]

0.6 L/min

(4 L)(0.05mol/L) 0.868

(1−0.868) = 19.7273 L/mol.min

10. Rate of reaction, -rA = k (CA0)2 (1-X)2

-rA = 19.7273 L/mol.min (0.05mol/L)2(1-0.868)2 = 8.5932×10-4 mol/L.min

0 5 10 15 20 25 30 35 40 45 500

10

20

30

40

50

60

70

80

90

100

Conversion against Residence Time

Y-Values

Residence Time (min)

Conversion (%)

Figure 8.1: Graph of conversion (%) against residence time (min) obtained from different total

flowrates of solution