B. The copper concentration in a contaminated salt sample was determined by flame atomic absorption spectrometry. In the analysis, a 10.00-g sample containing an analyte is transferred to a 250-ml volumetric flask and diluted to volume. A series of 10.0 mL of the diluted sample solution was pipetted into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cu were added to the flasks, and the solutions were then diluted to volume. The corresponding absorbances of each of the solutions are given below: Unknown, mL 10.0 10.0 10.0 10.0 10.0 Standard, mL 0.0 10.0 20.0 30.0 40.0 Absorbance 0.201 0.292 0.378 0.467 0.554 Calculate the copper concentration (a) in the diluted sample solution expressed in ppm Cu, and (b) in the salt sample as percent copper (%Cu).

What do you call the type of analytical method that relies on the absolute stoichiometric equivalences of balanced chemical reactions in order to compute the amount of analyte present in the sample?   Oxidative methods   Instrumental methods   Classical methods   Blank Correction Methods

1. What is the mass of Cu in the unknown sample solution? 2. What is the most probable identity of the unknown copper compound, assuming there is 1 mole of Cu per mole of the unknown? 3. In the preparation of Standard 1, how much of the prepared stock Cu(II) solution should be diluted to come up with the desired concentration?

The molar absorptivity constant of a particular chemical is 2.31 M/cm. Determine the concentration of a solution made from this chemical that has an absorbance of 0.408 with a cell path length of 1.12 cm.

A piece of Gold weighing 12,359 Kg is suspected of being contaminated with Iron. To perform an instrumental analysis and To confirm whether or not it contains Fe, a portion of the sample (0.954 g) is taken from the piece and dissolved with 25 mL of aqua regia. Heats up For its complete dissolution, it is cooled and made up to 100 mL. A 10 mL aliquot is taken from this solution and made up to 50 mL. From This last solution is given the appropriate treatment to visualize Fe+2, for which the 1,10-phenanthroline reagent is added. (it forms a complex that is red in color) and is taken to a visible spectrophotometer and with a 12 mm cell a absorbance of 0.45. Previously, a calibration curve of Fe+2 was obtained under the same instrumental conditions obtaining the following data: (view table) Calculate the purity of the gold piece, assuming impurities only due to Fe.

0.1040 g of a solid sample containing copper was dissolved by acid and transferred to a 250.00 mL volumetric flask and volume was made up with distilled water. The solution was then diluted by a factor of 20. The final solution was analyzed by atomic absorption spectrophotometry and the concentration was found be 3.109 ppm, What is the weight percentage of copper in the original solid sample? Keep four significant figures in your final answer. Do not try to include the "%" in your answer. e.g. if your final answer is 10.01%, only write 10.01 in the box.

A medical lab technician creates a standard solutions of percent hemoglobin in whole blood. The technician measures the absorbance of each solution at 520 nm and creates a standard curve of the absorbance versus percent hemoglobin in whole blood and finds the linear equation below, with an R2 of 0.9985. y = 0.0523 x + 0.072 A patient sample has an absorbance of 0.162. Using the standard curve data, calculate the percent hemoglobin in the patient sample

Discuss three practical applications of solvent extraction in analytical chemistry.

Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used when A) the quantity of sample analyzed or the instrument response varies from run to run.   B) the standard solutions and the unknown solution all have similar characteristics are unaffected by the other material in the sample.   C) the sample composition is unknown or complex and affects the analytical signal.

What is the significance of selecting a "representative" sample for chemicalanalysis, and how does this practice ensure accurate and reliable results withrespect to chemical analyses?