PART B. Spectrophotometric Determination of the Copper Content of a Penny 3.116 Mass of penny: g 1979 Date on penny: A-l03 17-1/00) Concentration of standard Cu solution: 300 M Volume, Standard Volume, 1 M Cu (mL) [Cu2-] (M) % Transmittance Absorbance 2+ HNO, (mL) (use Eq. 4) 2 00 3,22 3 22 Test tube 1 800 S00 S.00 2.82 Test tube 2 OIS Z.82 &.00 2 2.619 O. 24 Test tube 3 2o19 2.5S 2.55 O.300 Standard 2.60 2.l09 Unknown X - lg - log o.is/iou) log Co.74/100) 73 Concentration of Cu in unknown (penny) O 201 M (from calibration curve) Mass of Cu in sample (penny) . Recall that the volume of the solution obtained by dissolving the penny is 250.00 mL (0.25000 L). To calculate the mass of Cu in the penny, you will first need to calculate the moles of Cu. This is done by multiplying the concentration of Cu (in moles/L) by the volume (0.25000 L). Finally, multiplying the moles of Cu by the molar mass of Cu (in g/mole) yields the mass of Cu in the original sample. 128 % Percent Cu in penny = Remember that percent by mass is simply the mass of Cu in the sample divided by the total mass of the sample (X 100 %). Show your calculations in the space below. Attach the calibration curve to this page. O.204 U 250OL O.810 0.0128

(a) You measure the percent transmittance of a solution containing chromophore X at 400nm in a 1-cm path length cuvette and find it to be 50%. What is the absorbance of this solution? (b) What is the molar absorptivity of chromophore X if the concentration of X in the solution measured in question (a) is 0.5mM? (c) What is the concentration range of chromophore X that can be assayed if, when using a sample cell of path length 1, you are required to keep the aborbance between 0.2 and 0.8?

A 10.00 g sample containing an analyte was transferred to a 250 mL volumetric flask and diluted to volume. When a 10.00 mL aliquot of the resulting solution was diluted to 25.00 mL it was found to give a signal of 0.235 (arbitrary units). A second 10.00 mL aliquot was spiked with 10.00 mL of a 1.00 ppm standard solution of the analyte and diluted to 25.00 mL. The signal for the spiked sample was found to be 0.502. Calculate the weight percent of analyte in the original sample.

. A sample of cobalt is to be determined using absorption spectrum analysis. A 0.286 g sampleof a cobalt ore is crushed and digested in 1M HNO3. The stock solution is then diluted to 250.0mL in a volumetric flask (assuming the solution has a density = 1.00 g/mL). The analysis thenproceeds as follows: Sample Solution Std Co solution (11.2 ppm) Final Volume Transmittance                                               15.0 mL 0.00 mL 100.0 mL 54.1%                                               15.0 mL 5.00 mL 100.0 mL 19.9%Calculate the percent cobalt in the original ore sample.

3. The lead in a swab sample, lead standards, together with a blank were made up in 5.00 mL volumetric flasks using 0.2 % HNO3. 20 μL aliquots of these solutions were injected into the spectrophotometer and the absorbance measured at 217 nm. The following results were obtained. lead / ppb Absorbance 0 0.0591 10.00 0.0858 50.00 0.1926 100.0 0.3260 150.0 0.4594 200.0 0.5929 Swab sample 0.3700 (a) Determine the amount of lead in the swab sample in μg.

A third spectrophotometric method for the quantitative analysis of Pb2+ in blood uses Cu2+ as an internal standard. A standard containing 1.75 ppb Pb2+ and 2.25 ppb Cu2+ yields a ratio of (SA/SIS)std of 2.37. A sample of blood is spiked with the same concentration of Cu2+, giving a signal ratio, (SA/SIS)samp, of 1.80. Determine the concentration of Pb2+ in the sample of blood.

A spectrophotometer method for the quantitative analysis of Pb2+ in blood uses Cu2+ as an internal standard. A standard containing 1.75 ppb Pb2+ and 2.25 ppb Cu2+ yields a signal of 0.832 for Pb2+ and a signal of 0.351 for Cu2+. A sample of blood is spiked with the same concentration of Cu2+, giving a signal of 0.520 for Pb2+  and 0.289 for Cu2+. Determine the concentration of Pb2+ in the sample of blood.

A 10 cm 3 air saturated Fricke dosimetry solution in a 1 cm diameter tube is irradiated for 10 min in a 6~ source of gamma rays. The optical density measured at 304 txm in a 1 cm light path at 30~ was 0.260 after the completion of irradiation and 0.003 before irradiation. (a) What is the total dose in gray absorbed by the solution?(b) If 10 cm 3 of methanol is irradiated in the same tube for the same 10min, what is the absorbed dose in gray. The Z/A for methanol is 0.562 and that for the Fricke dosimeter is 0.553. Explain any assumption you make to solve the problem.

An unknown sample of Yellow 6 solution has the absorbance equal to 0.96. The slope of the Beer's law calibration plot constructed using a 3.8E-5M stock solution of Yellow 6 is 0.0117 (%) 1. What is the molar concentration of the unknown sample (in mole L-¹)? Please give your answer to 3 significant figures (1 additional SF is used to minimize rounding errors). M Hint

Bradford assay was used to determine bovine serum albumin (BSA) concentrations. The method works by binding Coomassie Brilliant Blue dye to protein standards and unknown, leading to a shift in the absorbance maximum of the dye. A stock solution of BSA is available (10 mg/ml) from which the protein standards were prepared. Bradford reagent, 290 ul, was pipetted into a transparent 96-well microplate. 10 ul of the protein dilution was added followed by mixing in the wells. After 5 min of incubation at room temperature, the plate was read in spectrum mode with the absorbance spectrometer of the microplate reader. The spectrum of the dye not bound to protein was also determined. Create a standard curve or regression equation that related the protein concentration and absorbance. An unknown BSA sample was prepared the same way as the standard and the OD was 0.35. determine the original concentration of the protein solution. The measurements can be seen below. 0.0625 Protein Concentration…