Both IR and UV spectroscopy are methods of measuring the wavelengths absorbed by a tested material. IR spectroscopy measures the absorbance of the tested material in the infrared spectrum, the section of the electromagnetic spectrum with a lower frequency than that observed in the visible light spectrum. Conversely, UV spectroscopy measures the absorbance of the tested material in the ultraviolet spectrum, the section of the electromagnetic spectrum with a higher frequency than that observed in the visible light spectrum. Both these methods can be used to identify compounds and analyze the structure of the compound. Though powerful tools in identifying various molecules and elements, there are limits the ability to detect using these methods.
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These similarities would indicate that the three substances tested had similar chemical makeup, confirming the theorized makeup of the precipitates. The slight differences in the spectroscopies would indicate that, while similar, the three substances were different in chemical makeup. This would confirm the ability to use both IR and UV spectroscopies as methods of identifying substances comparatively. When compared against the IR-spectroscopy of the 2,4-pentandione, the Al(acac)3 showed a much lower transmittance in the 1000-600 cm-1 range, this would most likely due to the presence of the aluminum ion. When Co(acac)3 was compared, it showed a much higher transmittance in the 2000-1000 cm-1 range, this is most likely due to the presence of cobalt in the molecule. When comparing Co(acac-NO2)3, there was a much higher transmittance in the range of 2000-400 cm-1, this is most likely due to the presence of the nitro group and the cobalt ion in the molecule. The transmittance was also shifted to the left by approximately 600 cm-1. No color change was seen during the lab. During the UV-spectroscopy, a 2.0*10-5 M solution of methanol was used as the spectroscopy fluid. To reach this concentration, the provided methanol was diluted twice. During this double dilution, there was the distinct chance that the concentration of the methanol was incorrectly diluted and a different …show more content…
Below are the calculations for determining the extinction coefficient for each of the three precipitates.
When comparing the UV-spectroscopies of Al(acac)3 and Co(acac)3, they both appear very close in absorbance and absorbance bands. On closer inspection, the maximum absorbance of Co(acac)3 is over 0.7 units higher than that of Al(acac)3. The absorbance band is also slightly wider, going from 254-400 nm, rather than 254-321 nm. This difference in the absorbance’s of these complexes is due to the metal that they are bound to, aluminum and cobalt. As discussed previously, the cobalt metal ion is both larger and has a different d count, this results in a differing absorbance, this being higher in the case of
These similarities would indicate that the three substances tested had similar chemical makeup, confirming the theorized makeup of the precipitates. The slight differences in the spectroscopies would indicate that, while similar, the three substances were different in chemical makeup. This would confirm the ability to use both IR and UV spectroscopies as methods of identifying substances comparatively. When compared against the IR-spectroscopy of the 2,4-pentandione, the Al(acac)3 showed a much lower transmittance in the 1000-600 cm-1 range, this would most likely due to the presence of the aluminum ion. When Co(acac)3 was compared, it showed a much higher transmittance in the 2000-1000 cm-1 range, this is most likely due to the presence of cobalt in the molecule. When comparing Co(acac-NO2)3, there was a much higher transmittance in the range of 2000-400 cm-1, this is most likely due to the presence of the nitro group and the cobalt ion in the molecule. The transmittance was also shifted to the left by approximately 600 cm-1. No color change was seen during the lab. During the UV-spectroscopy, a 2.0*10-5 M solution of methanol was used as the spectroscopy fluid. To reach this concentration, the provided methanol was diluted twice. During this double dilution, there was the distinct chance that the concentration of the methanol was incorrectly diluted and a different …show more content…
Below are the calculations for determining the extinction coefficient for each of the three precipitates.
When comparing the UV-spectroscopies of Al(acac)3 and Co(acac)3, they both appear very close in absorbance and absorbance bands. On closer inspection, the maximum absorbance of Co(acac)3 is over 0.7 units higher than that of Al(acac)3. The absorbance band is also slightly wider, going from 254-400 nm, rather than 254-321 nm. This difference in the absorbance’s of these complexes is due to the metal that they are bound to, aluminum and cobalt. As discussed previously, the cobalt metal ion is both larger and has a different d count, this results in a differing absorbance, this being higher in the case of