1. at what wavelength was Pb determined? 2. What is the slope of the calibration curve? 3. What is the y-intercept of the calibration curve? 4. The researcher determined the Pb content of water sample from a river suspected to be contaminated with Pb from a nearby factory by complexing with cyanidine and the absorbance measured was 0.405. What is the lead content of the water sample

The Beer’s Law plot of the standard curve for the equilibrium experiment was determined by plotting?   absorbance versus [Fe3+]   absorbance versus % transmittance   % transmittance versus [FeSCN2+]   absorbance versus [FeSCN2+]

Maria was tasked to determine the concentration of a Fe2(SO4)3 solution. She prepared 5 different standards of Fe2(SO4)3 using the table below as her guide. She ran the standards and the unknown solution through UV-VIS spectroscopy and recorded the absorbances of each solution.   HINT: use the dilution equation to determine the concentration of Fe2(SO4)3 in each test tube before preparing the standard curve. NOTE: No need to force the line to pass through zero. Just graph the data as is.   What is the slope of the line of the standard curve from the given data? What is the concentration of the unknown solution?

An unknown amount of a compound with a molecular mass of 270.57 g/mol is dissolved in a 10 mL volumetric flask. A 1.00 mL aliquot of this solution is transferred to a 25 mL volumetric flask, and enough water is added to dilute to the mark. The absorbance of this diluted solution at 355 nm is 0.495 in a 1.000 cm cuvette. The molar absorptivity for this compound at 355 nm is €355 = 6149 M-¹cm-¹. What is the concentration of the compound in the cuvette? concentration: What is the concentration of the compound in the 10 ml flask? concentration: How many milligrams of compound were used to make the 10 mL solution? mass: M M mg

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.

Absorbance is not proportional to which of the following? a. Intensity b. Molar Absorptivity c. Concentration d. Path Length