group report

Los elementos del grupo 7 (VIIb Mn, Tc, Re) con configuración d1 forman oxoaniones MnO42- que son isomorfos e isoelectrónicos al ion sulfato SO42-. Estos oxoaniones tienen geometría tetraédrica. ¿Es esto correcto?

1.) Beer's Law can be used to find the concentration of a solution by measuring its absorbance. The law is given by  ?=???A=ϵbC Where A is the absorbance, ?ϵ is the molar absorptivity, b is the pathlength of the light (the width of the sample cell), and C is the concentration of the solution.  A student is analyzing a solution of a metal, and finds that the absorbance of the solution is 0.532. If ?=187 L⋅g−1⋅cm−1ϵ=187 L⋅g−1⋅cm−1 and ?=1 cmb=1 cm , what is the concentration of the metal in solution (in g/L)?    * 352 * 2.84×10−32.84×10−3 * 2.84×10−22.84×10−2 * 96.8   2.) How many significant figures does the number 0.00358 have? Group of answer choices a.1 b.2 c.3 d.5   3.) A 10.00 mL solution of a certain food dye has a concentration of 1.47 g /L. What is the total mass of food dye in the solution? Report your answer with the correct number of significant figures.

4. To analyze the Cu(NO3)2 unknown solution in Part 3, your group constructed a plot of absorbance vs. concentration, commonly called a calibration curve or standard curve. The absorbance at the top of the peak (i.e., at the wavelength of maximum absorbance) was chosen for these measurements. What is the potential advantage of using the wavelength of maximum absorbance, rather than some other wavelength? Can you think of a situation in which you might want to choose a different wavelength? (Hint: Scientists often do not have the luxurý of analyzing pure substances dissolved in distilled water!)

What are the advantages and disadvantages of using quantum dots for fluorescence imaging?

Explain the meaning of the following terms and phrases: 1.1 Precision of a set of results.                                                                                              1.2 Noise around an analytical signal.      1.3 A shelf-life of an aqueous trace metal standard

Following is a table of data showing the absorbance of a solution of cobalt(II)  ion at different concentrations at a wavelength of 510 nm.  .      Absorbance          Concentration (M)         0.450                    0.044          0.691                      0.072          0.894                      0.096          1.210                      0.125          You are given a solution of  unknown concentration containing cobalt(II) ions, which gives you an  absorbance of 0.67.          Calculate the unknown conc., using data from  the table given  above.           (A = kC). Use the average ‘k’ value from the above set of data.

Compute the ionization potential for five-times ionized (Mg11+) and also compute the wavelength of the transition from n=2 to n=1 for that species

Absorbance measurements were taken on a series of Fe standards complexed with 1,10-phenanthroline. A plot of absorbance vs. concentration yielded a linear curve with the equation y=1.008e03x + 0.0395 (where y is the absorbance and x represents the Fe concentration in moles/L). Using this information calculate the Fe concentration (in ppm) in a 40.0-mL aliquot of ground water that produced an absorbance of 0.580.

Question 4

A student combines Fe(NO3)3 solution and KSCN solution to produce a solution in which the initial concentrations of Fe3+(aq) and SCN–(aq) are both 7.9 × 10–3 M. The absorbance of this solution is measured, and the equilibrium FeSCN2+(aq) concentration is found to be 1.8 × 10–3 M.             Fe3+ + SCN- <=> FeSCN2+ Determine the equilibrium constant for the above reaction

From experimental data, a plot of absorbance (in arbitrary units, a.u.) at a wavelength of 630 nm (on the y-axis) was plotted against the concentration (in mg/L) of Cu2+ (on the x-axis) in known solutions and a linear relationship was found with an equation of y = 7.22x+0.05. If an unknown solution had an absorbance of 1.20 a.u. at a wavelength of 630 nm, what is its concentration of Cu2+?

Why are sodium and lithium typically analyzed by atomic emission while transition metals such as lead and chromium are analyzed by atomic absorption?

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

Part C: Copper. A 0.275 M solution of Cu^2+ gives an absorbance reading of 0.788 at 620 nm. Another solution gives an absorbance reading of 0.340 under the same conditions. What is the concentration of the second solution in moles of Cu^2+/L and grams of Cu^2+/L

1. What factors are included in the Beer's law expression for determining how much light passes through a liquid solution? 2. How would your test results be affected if you left fingerprints on the sides of the cuvette in line with the light path of the spectrometer (or colorimeter)? 3. The chemical sunset yellow, also known as yellow #6, looks yellow. What color(s) must be absorbed by this chemical? RED YELLOW GREEN WHITE CYAN MAGENTA RGB System (Transmitted light) Additive color system colored light Rendered with Corel Draw 9 RGB pollete 40 M iscalled BLUE-VIOLET 4. Sunset yellow has an extinction coefficient of 20,000 M-1 cm-1 at a lambda max of 470 nm. What is the concentration of a solution that has an absorbance of 0.893?

Solutions that contain the FeSCN2+ ion are blood red (you will see this at the end of the second quarter of lab). Consider the regions of the visible spectrum in which the compound should absorb light and prepare a rough sketch of absorbance vs. wavelength for each solution. Label λ max on the graph. (Is this question asking for the graph of my data at the end)

Analyzing a mixture of salts with differing cations and/or anions can be far more complicated than analyzing a single simple salt. Interference between cations or between anions can greatly increase the complexity of the results. Using sound chemical knowledge, suppose your simple salt is a white granular solid. At what specific step in the cation procedure might you begin your analysis? Explain your reasoning.  The steps are:  Chemistry of Group 2 Cation, Cu2+ Chemistry of Group 3 Cations, Fe3+, Ni2+, Mn2+ Chemistry of Group 4 Cations, Ba2+, Ca2+