Spinach Extractions - Lab Report 3

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.

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.

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

Project 2: Food Dye Spectroscopy   How can you use serial dilutions to determine the relationship between concentration and absorbance? Graphs may also help in this explanation.

please help Part II Data Analytical Wavelength read from the spectra (nm): Absorbance at the analytical wavelength for the 5 mL/5 mL mix Absorbance at the analytical wavelength for the 4 mL/6 ml mix 628.5 0.875 0.704 3. Find the molar extinction coefficient from the 4 mL/6 mL mix. Pathlength: 1.00 cm Volume of Brilliant Blue: 4,00 ml Volume of DI water. 6.00 ml Absorbance at the analytical wavelength for the 4 mL/6 ml mix: 0,704 Concentration of Brilliant Blue in the 4 mL/6 ml mix (M): Molar extinction coefficient from the 4 ml/6 mL mix (M cm') 4. Average molar extinction coefficient for Brilliant Blue (M cm)

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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.

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Please complete Table 2 and show the calculations for protein concentration and the concentration of the undiluted sample.  a). Using Excel software, enter data from Table 1 to plot a standard curve (corrected average absorbance on Y-axis and protein concentrations on X-axis). The standard curve must contain correct labels on both axes. b). From the standard curve, obtain a best fit line and equation. c). Use the best fit equation and data from Table 2 to find the concentrations of proteins in sample A2-D2 and E1.  [onto your plotted standard curve, indicate where A595 of A2-D2 and E1 are located]  d). Calculate the concentrations of proteins in undiluted samples A to E. Thank you very much.

A student calibrated the mini-spectrophotometer with a blank solution, and then went to check their solution. They got a fingerprint on the cuvette while filling it. Because of this, the expected reading for the absorbance would be [Select] [Select] ✓ [Select] too high too low O which would cause the calculated value of Ke to be

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

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

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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

Calculate the concentration of the unknown MnO4 sample, given the following standard addition experiment. Step 1: A 2.00 mL aliquot of an unknown MnO4 sample was diluted to 100.0 mL and the absorbance measured to be 0.275. Step 2: A 2.00 mL aliquot of an unknown MnO4 sample was placed in a 100.0 mL flask. A 2.00 mL aliquot of a 100.00 ppm MnO4 standard was added to the flask and the absorbance measured to be 0.6. Report your answer to one decimal place.

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Project 2: Food Dye Spectroscopy   Which scale is most useful for reporting data from the spectrometer? Why?

Two samples were analyzed using a colormeter on a cellphone: one containing only distilled water, and another containing an unknown solution. The distilled water sample had a Red value of 206, while the unknown solution had a Red value of 118. Calculate the absorbance of the unknown solution. -log (4) A = -log a) -0.242 b) 0.573 c) 0.242 d) 0.000 CASAT

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A student measures the absorbence of an unknown after placing a sample in a cuvette which contained some water. How will this affect the concentration he reports?

A) A sample of dissolved oil in water has absorption in the infrared region. Which cuvette can be used for this quantification in IR spectrophotometer? B) Several processes are presented in Jablonski diagram. i) Name the processes A-H. S, т, So B ii) Compare both processes B and C. Energy