Overall the experiment provided significant data, despite problems with reagent contamination. Iron (III)-thiocyanate complexes in equilibrium, meaning that external and internal forces on the equilibrium can shift toward the reactants or the complex. External forces are changes to the chemical or physical environment that effect the equilibrium. Internal forces are changes to the bonds or chemical nature of the complex itself. These effects are used to study the optimal chromogenic reagent, meaning that any changes to the system should not change the performance of the chromogenic agent. The chromogenic reagent is the iron(III)-thiocyanate complex.
Time Duration: The maximum wavelength of the complex was found to be approximately 470 nm. Since the complex had a reddish-brown color and the use of complementary colors, the measured absorbance was within the expected value for the visible blue region. For the time duration, physical observation of the samples showed a fading in the color of the complex as time progressed.
As shown to the right in Figure 5, as time progresses …show more content…
Ideally, the sensitivity was calculated to be 50 ppm/Abs units; the slope of the graph is the equivalent of the sensitivity. The observed sensitivity was found to be 44.7 ppm/Abs units. This means that in one increment of absorbance, the concentration is 44.7 ppm or for 0.01 increment of absorbance, the concentration increases by 0.447 ppm. This shows a low sensitivity for the thiocyanate system. The detection limit was also calculated, which was found to be 0.4038 ppm. This correlates with the earlier attempts in analyzing solutions with concentrations less than 1 ppm. While inaccurate due to the rapid conversion of the complex, if the absorbance measured as the thiocyanate was added, then the signal/noise ratio may have been small and relatively good spectra could have been
Time Duration: The maximum wavelength of the complex was found to be approximately 470 nm. Since the complex had a reddish-brown color and the use of complementary colors, the measured absorbance was within the expected value for the visible blue region. For the time duration, physical observation of the samples showed a fading in the color of the complex as time progressed.
As shown to the right in Figure 5, as time progresses …show more content…
Ideally, the sensitivity was calculated to be 50 ppm/Abs units; the slope of the graph is the equivalent of the sensitivity. The observed sensitivity was found to be 44.7 ppm/Abs units. This means that in one increment of absorbance, the concentration is 44.7 ppm or for 0.01 increment of absorbance, the concentration increases by 0.447 ppm. This shows a low sensitivity for the thiocyanate system. The detection limit was also calculated, which was found to be 0.4038 ppm. This correlates with the earlier attempts in analyzing solutions with concentrations less than 1 ppm. While inaccurate due to the rapid conversion of the complex, if the absorbance measured as the thiocyanate was added, then the signal/noise ratio may have been small and relatively good spectra could have been