Dopamine absorbs light at a λmax of 265 nm. A sample of dopamine (molar mass 153.18 g/mol) was prepared by dissolving 1.02 mg of dopamine in enough water to make a 500.00 mL sample. The UV absorbance at 280 nm was found to be 0.450 in a 1.500 cm cuvette. What is the molar absorptivity of dopamine in L mol-1 cm-1?

Dopamine absorbs light at a λmax of 265 nm. A sample of dopamine (molar mass 153.18 g/mol) was prepared by dissolving 1.02 mg of dopamine in enough water to make a 500.00 mL sample. The UV absorbance at 280 nm was found to be 0.450 in a 1.500 cm cuvette. What is the molar absorptivity of dopamine in L mol-1 cm-1?

Macroscale and Microscale Organic Experiments

7th Edition

ISBN:9781305577190

Author:Kenneth L. Williamson, Katherine M. Masters

Publisher:Kenneth L. Williamson, Katherine M. Masters

Chapter14: Ultraviolet Spectroscopy, Refractive Indices, And Qualitative Instrumental Organic Analysis

Section: Chapter Questions

Problem 4Q

See similar textbooks

Similar questions

Calculate the absorbance of an organic dye [C =7×10-4 mol L−1] ,knowing that the molar absorptivity ∈= 650 mol L−1 cm−1 and that the length of the optical path of the cell used is 2×10−2 m. What would happen to the absorbance if the cell used was of double its present thickness?
How does pipetting laboratory techniques affect absorbance values when using UV-Vis Spectrophotometry?
Why is it most accurate to measure absorbances in the range A = 0.3 to 2?
Fe+3 (aq) + SCN – (aq) FeSCN +2 (aq) She mixes 4.00 mL of 2.00 mM SCN– and 5.00 mL of 2.00 mM Fe+3 ions, then diluting with 1.00mL of water to give a total volume of 10.00mL. She measures the absorbance of the solution asbeing 0.210. If she has previously calculated the molar absorbtivity constant (ε) of the product tobe 2583 cm–1 M–1, what is her best estimate for the K value for this reaction?
Given the following parameters, what is the expected absorbance?c = 250 mmol/Ll = 0.5 cmε = 10 M-1 cm-1 a. 0.5 b. 1.0 c. 1.5 d. 1.25
A student prepared several solutions of Molecule Bright, each at a different concentration. The absorbance of each solution was measured at 405 nm with a path length of 0.730 cm. The student then plotted the absorbance of each sample vs. its concentration (in mM), and found a best-fit line of y = 3.726x + 0.828. Calculate the molar absorptivity of the Molecule Bright (in M-1 cm-1).
Examine the given Beer's law standard curve for an unknown dye measured in a 1.0 cm cuvette. Plot of absorbance at 542 nm versus concentration. There is a best-fit line on the plot and the equation is given as y=15200x-0.018 What is the molar absorptivity (in M–1cm–1) of the unknown dye at 542 nm?
A student prepared several solutions of an unknown molecule, each at a different concentration. The absorbance of each solution was measured at 630 nm with a path length of 0.760 cm. The student then plotted the absorbance of each sample vs. its concentration (in uM), and found a best-fit line of y = 0.00626x + 0.00732. Calculate the molar absorptivity of the unknown molecule (in M-1 cm-1).
A student uses visible spectrophotometry to determine the concentration of CoCl2(aq)CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq)CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510nm510nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration. The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60g2.60g of CoCl2CoCl2 (molar mass 130.g/mol130.g/mol) in enough water to make 100.mL100.mL of solution. What is the molar concentration of the solution? a.) 0.200M b.) 0.500M c.) 1.00M d.) 5.00M
A standard 1 mL cuvette is three-quarters filled with a 1 in 6 dilution of 24 μmol.L-1 oxyhaemoglobin. The absorbance is measured at 600 nm. A few drops of a live yeast suspension is added to the cuvette (without significantly changing the volume). The absorbance is remeasured at the same wavelength as above and is found to be 0.60, a decrease of 0.35 on the first measurement.What is the molar absorbance coefficient of the deoxyhaemoglobin at 600 nm? (do not enter the units in the answer, 2 decimal places)