Hello, can someone please help me? I'm stuck on a question:
I'm doing an analysis of the absorbance of FeSCN2+ at it's max wavelength (i.e. 450nm where abs=0.154)The species I used to make the solution tested were Fe(NO3)3, HNO3, and KSCN.
Now, the question is: Suppose there are one or more interfering species in the solution, which also absorb more or less strongly at this same wavelength. How could/should you deal with such a situation of overlapping absorbances?
I've scanned all my notes and I'm still stuck. I think it may have something to do with finding the equilibrium concentrations and then converting values using a ratio formula using the absorbance and concentration values...
A/A = C/C? I think i may be wrong, can someone please explain this theory question to me?
Sure! I'd be happy to help you understand how to deal with the situation of overlapping absorbances in a solution.
When there are interfering species in a solution that absorb at the same wavelength as the species you're trying to analyze, it can be challenging to accurately measure the absorbance of your target species. However, there are a few approaches you can take to address this issue:
1. Blank Correction: One common method is to prepare a "blank" solution that contains all the components of your sample solution except for the target species. By measuring the absorbance of this blank solution at the wavelength of interest, you can determine the contribution of the interfering species to the overall absorbance. Then, you subtract this value from the absorbance of your sample solution to obtain the corrected absorbance for the target species.
2. Selective Reagent: Another approach is to add a selective reagent that reacts only with the interfering species and forms a product that either doesn't absorb at the target wavelength or absorbs weakly. This way, you can selectively remove the interfering species from your solution, leaving only the target species to be measured.
3. Wavelength Scanning: If there are multiple species absorbing at similar wavelengths, you can try scanning the entire wavelength range to identify the wavelength(s) where the target species has maximum absorbance while the interfering species have relatively lower absorbance. This way, you can choose a wavelength where the interference is minimized and measure the absorbance at that specific wavelength.
In your case, you mentioned analyzing the absorbance of FeSCN2+ at its maximum wavelength of 450nm. To deal with any potential overlapping absorbances, you could follow the steps mentioned above. It is important to note that the specific method chosen would depend on the nature of the interfering species and the target species, as well as the availability of appropriate reagents and equipment.
I hope this explanation helps you understand how to approach the situation of overlapping absorbances in a solution. If you have any further questions, please let me know!