The intensity of red light (680 nm) absorbed by a solution of green dye was found to be 1.59 V and the intensity of light when no dye was present (the blank) was found to be 2.75 V.  What is the absorbance of the solution of green dye? Type only the value in the answer field. Report  answer to three significant figures.

Consider the analysis of a sample of iron using atomic absorbance spectroscopy. Which of the following statements are true? Select all that apply.   The iron sample is aspirated into the flame, where the solvent evaporates and the iron analyte is atomized. The hollow-cathode lamp for iron emits wavelengths of light unique for iron. A detector measures the amount of light generated by the flame and not absorbed by iron. The iron atoms in the flame absorb some of the light emitted from the hollow-cathode lamp. The flame replaces the cuvet of conventional spectrometers and the flame pathlength is typically 10 cm.

A student mixed 5.00 mL of 0.100 M Fe(NO3)3 with 50.00 mL of 2.00x10−4 M KSCN. The student measured the absorbance of one aliquot of the solution at a wavelength of 447 nm, with a pathlength of 1.00 cm. The absorbance reading was 0.615. Compute the following quantities a. [FeSCN2+]eq = b. (mols FeSCN2+)eq = c. (mols Fe3+)initial = d. (mols SCN−)initial = e. (mols Fe3+)eq = f. (mols SCN−)eq = g. [Fe3+]eq = h. [SCN−]eq = i. Keq=

When absorption spectroscopy is used for quantitative analysis, concentration of the analyte is directly proportional to A) molar absorptivity D) absorbance D) Which of the following equations provide the fundamental reason why absorbance above 4 tend to produce significant noise? A) A = EbC No go B) wavelength E) beam path length ΔΕ KT C) transmittance B) E = Eº - RInA nF E) E = hv C) A = -logT Which of the following statements concerning fluorescence spectroscopy is incorrect? A) Fluorescence intensity is directly proportional to the fluorophore concentration. B) Fluorescence happens faster than phosphorescence. C) Fluorescence is more sensitive for quantitative analysis than absorption spectroscopy. D) Fluorescence does not need an optical source because it is a form of emission spectroscopy.

None

SPECTROPHOTOMETRY Two groups in a BIO 120 lab extracted a blue-violet pigment from mayana plant which was to be used as a natural dye for Philippine textiles. To determine the concentration of the pigment isolated, each group made a standard curve using commercially available indigo dye in dimethylsulfoxide (DMSO). The following data were obtained by the two groups: Table 4. Absorbance readings of standard solutions of varying concentrations of indigo dye in DMSO. Pure DMSO 0.115 Standard solutions (ppm) Group 1 Data Group 2 Data 0.2 0.398 0.224 0.4 0.563 0.437 0.6 0.732 0.603 0.8 0.833 0.811 1.0 1.008 0.966 1. Show the constructed standard curves of the two groups with proper figure titles. 2. Which of the two groups generated a better standard curve? Justify your answer by providing the R? value for each data set. 3. The extracted pigment has an absorbance of 0.983. When a 0.2 mL-aliquot of the extract was diluted to 1.0 mL, the absorbance of the diluted solution was found to be…

The students conducted the assay for LDH activity using the two serum samples. Each cuvette (path length 1 cm) contained 3ml of a suitable assay buffer (including pyruvate as substrate). 20 microlitres of either serum was added to the cuvette and the absorbance values immediately recorded at the optimum wavelength for a period of 5 minutes (absorbance readings taken every 30 seconds).   Protein concentration of serum sample (mg/ml) Change in absorbance at optimum wavelength per minute Control serum (C) 8 -0.04 Diseased serum (D) 7.8 -0.6 1c. Using the molar absorption coefficient of NADH as 6220 M-1 cm-1, and by application of the Beer-Lambert law, estimate the enzyme activity in the two samples (C and D). Express activity as moles per second.  1d. Estimate the specific activity of the two samples (moles per second per microgram).

The transmitance is 14.4%

What absorbance value corresponds to 44.7% T? A = 0.357 A 0.0126 M solution of a certain analyte exhibits 44.7% T at a wavelength of 280 nm. What will the percent transmittance be for a 0.0278 M solution of the same analyte? Assume the pathlengths for each measurement are equal. 2.02 Incorrect

What is its Molar Refraction in cm /mole of a solution of a compound (MW = 250.67 g/mole) having a density 0.79 g/cm when its refractive index was measured 1.7 at 25°C. ? Final answer in 2 decimal places. C = 12.01; H =1.00, O = 15.99