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1.Why should absorbance be less than 2? Please explain in terms of light transmittance.
2.Why is a linear calibration curve important? Couldn't interpolation be used to predict values within the calibration range?
3.If the extinction coefficient can be calculated from a single absorbance measurement at a known concentration of a compound, why is a calibration curve necessary, even if the measured absorbance is below 1?
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- If you are setting up a standard curve using a UV spectrophotometer and a set of standards, and your unknown sample gives an absorbance value higher than your most concentrated standard. What would need to be done to accurately calculate the unknown sample concentration? I humble request to you please give the answer within 1 hrs so that I do my work.Why is it important to acquire a reference spectrum and subtract it from the sample’s spectrum? Why are quartz cuvettes better for UV-visible absorption spectroscopy than polystyrene cuvettes, especially at lower wavelengths (UV)? What would happen if you put too much of a compound in the cuvette during the spectral measurement? Why is it important to avoid any scratch on the cuvette? Could you use a compact fluorescent light (CFL) bulb to perform UV-visible absorption spectroscopy? Why/why not?What should you put into the reference cuvet when doing UV-visible Absorption spectrometry.
- Q1. Why is it important to acquire a reference spectrum and subtract it from the sample’s spectrum? Q2. Why are quartz cuvettes better for UV-visible absorption spectroscopy than polystyrene cuvettes, especially at lower wavelengths (UV)? Q3. What would happen if you put too much of a compound in the cuvette during the spectral measurement? Q4. Why is it important to avoid any scratch on the cuvette? Q5. Could you use a compact fluorescent light (CFL) bulb to perform UV-visible absorption spectroscopy? Why/why not? Q6. Predict the maximum absorption wavelength for 2,4-heptadien-6-one using Woodward-Fieser rules. Q7. Why are n-π* transitions generally of low intensities/low absorptions? Q8. What photon energy and wavelength would you need to send on a compound having an energy gap (Eg) of 2.7 eV? Detail your answer with appropriate information. Q9. Using molecular orbital theory/concept (draw the important molecular orbitals), explain the difference in absorption for the…If you goop on more sunscreen to double its thickness, absorbance will be doubled. What will be the transmittance near 300 nm and what percentage of ultraviolet radiation is blocked?Why acid is added to the solution when analyzing mixtures in the UV-Visible absorption spectrometry.
- Why is it necessary to run a blank before measuring the absorbance of a sample? To allow the lamp and electronics of the spectrophotometer to warm up before taking the sample absorbance reading. So that scattered light will be filtered before hitting the photodetector. To account for the absorbance caused by the cuvette and the solvent To account for the absorbance caused by the cuvette alone .The spectrophotometer is used to measure absorbance experimentally. Briefly, explain how this is accomplished.Monomer-dimer formation can affect the absorbance measurements using Beer’s law, it is an example of: A. chemical deviation B. instrumental deviation C. real deviation D. instrumental deviation
- When compounds are prepared for IR analysis, they usually have to be dehydrated completely and then dissolved in a solvent other than water. Can you think of a reason why you might not want to have any H2O mixed in with your unknown compound when collecting its IR absorbance? Explain your rationale with respect to any observations about the spectra.(UV spectroscopy lab, organic chemistry 2) If the extinction coefficient can be calculated from a single absorbance measurement at a known concentration of a compound, why is a calibration curve necessary, even if the measured absorbance is below 1?A) Calculate the concentration of an experimental sample with an absorbance of 0.355. Is this the trend you expect to see for this experiment using an XY scatter plot?