Spectrophotometry Lab & Report (3)

Label the graph with the correct axes for a standard curve used in a spectrophotometry experiment. y X Answer Bank Concentration (M) % Transmittance Sample # Absorbance Density (g/L)

When do you need to blank a spectrophotometer (Spec 20)? After completing all data collection. After the wavelength is changed. Before running a set of samples. Between each sample, even if the wavelength remains the same.

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.    Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.378 0.379 0.377 What is the corrected absorbance?

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.    Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.388 0.389 0.388 What is the concentration of Cu in analyzed solution (mg/L) for each trial?

Do your graphs show the trends a)you expected based on what you know about absorbance and transmittance using a spectrophotometer? Why or why not? b) why does absorbance data relate more conveniently to concentration that does transmission data?

Unce started, this test must be completed in one sitting. Do not leave the test befa Remaining Time: 31 minutes, 25 seconds. Question Completion Status: A Moving to another question will save this response. Question 13 The calibration standard (or internal standard) for H spectrum is TMS delta (6) high-field or upfield side low-field or downfield side MHz AMoving to another question will save this response. MacBook Air O00 O00 F4 F7 F6 F5 F3 F2 F1

The maximum number of spectra that can be recorded per second by ToF-MS is limited by the time taken by the slowest ions to go from the source to the detector. If the slowest ion took 45.6 microsecond to travel, at what frequency could you record spectra if a new extraction cycle were begun each time this heaviest ion reached the detector? 30000 spectra/s 10000 spectra/s 11000 spectra/s 500 spectra/s 22000 spectra/s

Short Answer 1a. Question shown in picture.

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Please help

Which of the the following is false regarding spectrophotometry? A. The concentration of a sample increases with path length of the curvette or sample holder since the absorbance increases B. when absorbance increases, transmittance decreases C.The absorbance coefficient depend on wavelength of light and type of sample.

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 .

For my lab I had to find the unknown concentration of a solution. I found wavelength max of the potassium chromate. Then used that max to find the absorbtion for my sample dilutions. Based on my attached graph. Is my unknown concentration #  making sense? Or did I make an error with the absorbance I wrote down in the lab. I did my calculations when I got home. They are correct, but my unknown concentration amount doesn't look like it will even be on the graph. Or am I wrong. Please  advise and explain. Thank you

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.

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?

QUESTION 4 4. The main difference between "in-time" and "in-space" spectrophotometer design is that the former uses timed mirrors to alternate measurements between reference and sample using the same detector, while in-space uses a beamsplitter to send light through a different path to the same detector which is able to retrieve the signal using lock- in amplification. A. False B. True

1. What is the concentration of the dye in a solution with a percent transmittance reading of 61.6% at 570 nm? 1a. If the solution in Part 1 was made by taking 10.00 mL of a stock solution and diluting it to 100.00 mL, what is the concentration of the dye in the stock solution?

" Spectrophotometric analysis" refers to methods that are based on light absorbance. O True False

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.

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

If 50.0 ml of water is added to 50.0 ml of a blue dye solution, and the newly diluted silution is placed in the spectrophotometer, what do you think would happen to the absorbance? choose all that apply! a. there would be no change  b. it would increase c. there is not enough information to answer the question d. it would decrease

Please refer to the graph in the lab document. If the absorbance of a solution containing FeSCN2+ is found to be 0.7500, what is the concentration of this solution? O 2.0 x 10-4M (2.0 times 10 to the minus 4th power M) 2.6 x 10-4 M (2.6 times 10 to the minus 4th power M) 0.7500 M O 1.6 x 10-4 M (1.6 times 10 to the minus 4th power M) 1.0 x 10-4 M (1.0 times 10 to the minus 4th power M) O 3.6 x 10-4M (3.6 times 10 to the minus 4th power M) 3.0 x 10-4 M (3.0 times 10 to the minus 4th power M)