Question 3 Why is it necessary to run a blank before measuring the absorbance of a sample? O To account for the absorbance caused by the cuvette alone. So that scattered light will be filtered before hitting the photodetector. To account for the absorbance caused by the cuvette and the solvent O To allow the lamp and electronics of the spectrophotometer to warm up before taking the sample absorbance reading.

Question 3 Why is it necessary to run a blank before measuring the absorbance of a sample? O To account for the absorbance caused by the cuvette alone. So that scattered light will be filtered before hitting the photodetector. To account for the absorbance caused by the cuvette and the solvent O To allow the lamp and electronics of the spectrophotometer to warm up before taking the sample absorbance reading.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter26: Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 26.1QAP

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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 .
12) If gloves are not worn when handling the cuvette in a spectrophotometry xperiment, how would this affect the absorbance reading (higher, or lower, or same) and ow would it make the concentration look, higher or lower?
state if true or false 1. Prior to a fixed point or wavelength reading, spectral scanning can be done to determine the maximum absorbance wavelength of a sample. 2. The purpose of a diffraction grating is the same as that of a prism. 3. In any UV-VIS spectrophotometer, the light is filtered first to a single wavelength or narrow range before it hits the sample 4. In any UV-VIS spectrophotometer setup, the detector always comes right after the sample container. 5. It is necessary to set the blank before each reading even if the only difference between the sample solutions is the amount of analyte. 6. Prior to a fixed point/wavelength reading, spectral scanning can be done to determine the maximum absorbance wavelength of a sample.
For the experimental data used in this lab, why was it okay to use the absorbance values instead of concentrations?
Your calibration curve will be generated using absorbance and concentration data. However, you collected %Transmittance data in the lab. Could you use a plot of %Transmittance versus concentration to generate a calibration curve? Why or why not?
A sample has a percent transmittance of 50.0%. What is its absorbance?
True or False. 1. The absorbance of a sample is equal to the negative logarithm of the transmittance. 2. Winkler method of dissolve oxygen determination is an example of iodometry. 3. A diazo compound is produced when nitrite is reacted with sulfanilamide in acidic solution. 4. Atomic Absorption Spectroscopy can be used to analyze the functional groups of organic substances. 5. A diode array spectrometer use an absorption or interference filters for wavelength selection and a photoelectric device for measuring radiant power. 6. The oxidation state for the manganese in the brown solid which precipitate in Winkler method is +3 7. In Winkler method, the iodine produced is oxidized during sodium thiosulfate titration to iodide ion. 8. When the pH of the solution is adjusted to pH greater than 12, the EDTA reacts with magnesium ions only, because calcium precipitates as calcium hydroxide.
Why it is important to measure the absorbance in the range of 0.4 to 0.9.
When using cuvettes to measure the absorbance of a solution, why is it necessary to only hold the cuvettes near the top?
In spectophotometry, what should be done if there is a greater absorbance reading than the most concentrated solution?
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 did not wipe your fingerprints off from the cuvette before measuring absorbance in a spectrophotometer, what would you expect to happen to your absorbance reading? Explain your answer.