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Figure 66: The model for the interaction of en with Ni2+
Note that in the notation of the model shown in Figure 66; we have used the formation
constants for the protonation of the ligand, as given in the equations above, and the stepwise equilibrium constants for the complex formations, as also shown in the equations
above. ReactLab™ allows both notations.
The data
The data set is a titration of an acidified solution of Ni2+ and en with a relatively
concentrated NaOH solution. The ionic strength has been maintained at approximately 1M
with NaClO4. The definition of the concentrations of the components is shown in Figure 67.
Figure 67: Component concentrations in ‘Beaker’ and ‘Burette’
10 ml of a solution with [Ni2+]=0.029M, [H+]=0.237 M and [en]=0.098 M have been titrated
with 10 ml of a 0.314 M solution of NaOH in steps of 0.200 ml.
The added and total volumes as well as the total component concentrations are listed in the
‘Data’ worksheet.
The spectral series and absorption profiles at all wavelengths as shown in Figure 68.
0.12
0.12
0.1
0.1
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0
0
400
420
440
460
480
500
520
540
560
580
600
0.0
2.0
4.0
6.0
8.0
10.0
12.0
Figure 68: Series of measure spectra and absorption profiles, as executed in Excel
and the 3D view in Matlab
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ReactLab™ EQUILIBRIA 1.1