Lab Report Experiment 3

750 400 11. Short answer. Refer to the color wheel on the right. If a solution is illuminated with white light and absorbs all wavelengths between 480 and 560 nm, what color would it appear to be? Violet Red 430 630 Blue Orange 480 590 Green Yellow 560 12. Short answer. You will need the color wheel on the right. Look at the absorption spectrum of the solution shown on the right. What color would this solution be? 800 13. Short answer. Look at the image of a spectrophotometer on the right. Structures/knobs A-E are labeled. Which knob will you have to use to zero the instrument itself? 20D BIOLOG. 14. Short answer. According to Beer's Law, given that Molar Absorptivity and path length is usually constant, Absorbance A is directly proportional to 15. Choose the one answer that fits best. Which of these is not standard components of a spectrophotometer? a. A sample chamber to hold your tube with sample solution b. A light source c. A prism or grating to filter out certain wavelengths of…

Why must solutions with high concentrations be diluted prior to analysis via Beer's Law? A. The relationship between absorbance and concentration is not linear at high concentrations. B. The detector will reach its detection threshold. C. The photon source is too weak to provide accurate results. D. There is no need to work with dilute concentrations; any concentrations will work. E. The molar absorptivity of a compound is dependent on its concentration.

Please help

Please help

Determine the standard concentration of A through E and then the absorbance. I just need clarification on if I add together the two ml values given.

For the experimental data used in this lab, why was it okay to use the absorbance values instead of concentrations?

A student weighed out 0.150 g of protein powder and dissolved it in 100 mL of water (Solution 1). The student then diluted this solution by transferring 1 mL into a 25 mL flask and diluting with water (Solution 2). Finally, 1 mL of that solution was transferred to a test tube and combined with 4 mL Bradford reagent. The absorbance of the solution in the test tube was 0.11. Assuming that the best fit linear line of the standard curve was y = 0.04144 x + 0.01521 (μ g mL), calculate the percent protein by mass in the original protein powder.

True or False 1. Photodiode arrays are devices within the instrument that help amplify the signal of a sample. 2. Atomic spectroscopy requires the atomization of a sample, which involves nebulization and eventually volatilization to form an elemental vapor. 3. Organic compounds are normally analyzed in atomic spectroscopy despite their small electronic transition range.

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.

I need help. Using a standard curve: Another student produced the standard curve shown here ( Fig.2.2) which shows the linear relationship between absorbance and Cu2+ concentration. They then measured the absorbance of their unknown solution to be 0.48126 AU. Use their trendline equation to calculate the concentration (M) of Cu + in their Unknown Solution. Show your work and consider sig figs.

This question uses the same data as the previous question. The calibration curve is a graph of absorbance versus concentration. Absorbance is a dimensionless quantity. The slope of the calibration curve is m = 2.24 x 10^4 M^-1. Find the concentration detection limit.

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…

Which is TRUE for spectroscopy of a mixture?   A. The absorbance for a mixture at a particular wavelength is the sum of the absorbances for the components that absorb at the particular wavelength.   B. Spectrophotometers can differentiate between mixture components that absorb at the same wavelength.   C. Each component in a mixture has the same molar absorptivity at the same wavelength.   D. The concentration for each component in a mixture is easily calculated by least squares for guesses of each component when the individual spectra are well resolved.

Hh.130.

B.  Quantitative Spectroscopy   Prepare two graphs, %T vs. Concentration and Absorbance vs. Concentration, using the data for the cobalt standards.  The concentrations of Cobalt standards 2-4 can be calculated using simple dilution calculations. Concentration should be on the x-axis for each of these graphs.  The first should clearly show some curvature while the second should be a linear curve. Using the absorbance graph you can determine the concentration of the unknown. Take the absorbance value for the unknown and find that value on the y-axis.  Draw a horizontal line from that point on the y-axis to the plotted line.  From the point where the horizontal line intersects the plotted line, draw a vertical line straight down to the x-axis.  Record the value from the point where you hit the x-axis as the unknown concentration.

Please provide the correct answers based on the following attached data.

Show the Atomic Fluorescence Spectrometer schematically.

3. Using the data at right: a. Calculate the absorbance of each sample. You will need to express the %T values as decimals before calculating the logarithms. (e.g., for T = 25%, A = -log 0.25 = 0.602) b. Use the graph paper on the back of this page (or a spreadsheet) to plot absorbance vs. concentration. Make a proper graph, with labeled axes, uniform scales, etc. Use a ruler to draw the best-fit line.. C. Use the graph to find the concentration of the un- known sample. (Draw dotted lines on the graph showing how you found your answer.) CONCENTRATION PERCENT (ppm) TRANSMISSION 0 100.0 100 74.1 200 54.9 300 40.7 400 30.1 500 22.3 unknown 31.6 ABSORBANCE

3. If you wished to study the molecule below by measuring absorbance, what wavelength should you set your spectrophotometer to? 1.6 Absorbance 1.4 1.2 1.0 0.8 0.6 0.4- 0.2- ME 0.0 300 400 600 Wavelength (nm) 500 Solutions and Mol....pdf 2 700 20221027_141317.jpg 800

At the end of the experiment you will be assessing the purity of your aspirin by measuring its absorbance at 525nm. If the absorbance measurement is found to be 0.040 then what is the % salicylic acid impurity in your aspirin? a. 0.06 b. 0.25 c. 0.15 d. 0.44 e. 0.35