Iron (III)-Tiocyanate Complexs In Equilibrium

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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.
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To measure the linearity of the iron(III) thiocyanate system, the 300 ratio was used to optimize the absorbance. The higher ratios provide large absorbance readings, however due to the extra reagent, the maximum wavelength shifts. These shifts reduce the reliability of the data.
As shown to the left (Figure 9), the concentration was plotted against absorbance. The graph shows a linear curve. The correlation coefficient, depicted on the graph, was approximately equal to one. This means that the data follows the linear curve. However, multiple errors can be introduced and lessen the validity on the Beer’s Law
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Chemical errors can result in not properly determining or making the required solution concentration. Another chemical error can also be side reactions with substances in the solvent. As seen in the anion analysis, solvent composition can have a negative effects on the measure of the absorbance. Errors can also arise from the instrument being used. At low concentrations, the signal read by the spectrophotometer will contain a large amount of noise, meaning that the signal to noise ratio decreases. This causes the spectra to have broader areas. The sensitivity of the iron(III)-thiocyanate system was also determined. Using a series of dilutions, sample concentration were made between 1-4 ppm. The sensitivity was determined by plotting the absorbance against the concentration. As shown below in Figure

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