Group No-03: 2102036,2102037,2102042,2102047
Experiment No: 03
Experiment Name: Potentiometric titration of ferrous ion with standard potassium
dichromate solution
Data Calculation:
Table : Variation of Electrode Potential (E) with Volume of K₂Cr₂O₇ Added, and
Corresponding First and Second Derivatives of E with respect to Volume.
Volume of
K2Cr2O7
added,mL
0.0
0.6
1.1
1.6
2.1
2.6
3.1
3.6
4.1
4.6
5.1
5.6
6.1
6.4
6.6
6.8
6.9
7
7.2
7.4
7.6
8.1
8.6
9.1
9.6
10.1
10.6
11.6
Potential
E(mV)
V(average
volume,mL)
dE/dV
V(average
volume,mL)
d2E/dV2
315
346
356
367
376
384
393
400
409
417
426
437
455
473
488
510
593
690
712
734
749
758
762
766
770
778
781
786
0.3
0.9
1.4
1.9
2.4
2.9
3.4
3.9
4.4
4.9
5.4
5.9
6.3
6.5
6.7
6.9
7.0
7.1
7.3
7.5
7.9
8.4
8.9
9.4
9.9
10.4
11.1
11.7
10
20
20
18
18
18
16
18
16
18
20
36
60
75
110
850
970
110
80
60
18
8
8
8
8
8
8
15
0.6
1.1
1.6
2.1
2.6
3.1
3.6
4.1
4.6
5.1
5.6
6.1
6.4
6.6
6.8
6.9
7.0
7.2
7.4
7.7
8.1
8.6
9.1
9.6
10.1
10.7
11.4
8.8
18
-3
-4
-4
-3
-4
4
-4
4
4
32
60
60
75
4933
0
-5733
-120
-100
-120
-20
0
0
0
0
0
12
10
Graphical Analysis:
Generated EMF vs Volume of K2Cr2O7
800
750
Generated EMF,E(mV)
700
650
600
550
500
450
400
350
300
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
10.0
12.0
Volume of K2Cr2O7(mL)
First derivative plot
1000
900
800
700
dE/dV
600
500
400
300
200
100
0
0.0
2.0
4.0
6.0
8.0
Average volume of K2Cr2O7 added,mL
Second derivative plot
5500
3500
d2E/dV2
1500
-500 0.0
2.0
4.0
6.0
8.0
10.0
-2500
-4500
-6500
Average volume of K2Cr2O7 added,mL
Calculation
Volume of Iron solution = 20 ml.
Concentration of K2Cr2O7 solution = 0.017 M
From graph, Required volume of K2Cr2O7 solution = 6.9 mL
∴ Concentration of Iron solution =
6 x 0.017 x 6.9
20
= 0.035 N
So, Concentration of Fe2+ solution is 0.035 N
For stoichiometry, 1000 mL 1M K2Cr2O7 ≡ 6 x 55.85 gm of Fe2+
∴ 6.9 ml 0.017M K2Cr2O7 ≡
6 x 55.85 x 0.017 x 6.9
1000
g of Fe2+ = 0.039 g of Fe2+
So, the amount of Ferrous ion (Fe2+) present in the solution is 0.039 g.
Result
Concentration of Fe2+ solution is 0.035 N
The amount of Ferrous ion (Fe2+) present in the solution is 0.039 g.
12.0
0