Fe lab

A water sample was analyzed for iron content using the iron-phenanthroline method. Using the set of data from Question 15 (as presented below), Reagent Blank Absorbance Absorbance (au) Reagent Blank Absorbance 0.003 Concentration of Stock Solution: 10 ppm Volume of Stock Solution (mL) Total Volume of Standard Solution (mL) 0.50 10.00 1.00 10.00 2.00 10.00 3.00 10.00 4.00 10.00 5.00 10.00 Volume of Trial Unknown Solution (mL) 1 5.00 2 5.00 3 5.00 find the true concentration of Fe2+ of the original sample. A) 5.12 ppm B) 2.56 ppm 2.52 ppm D) 5.05 ppm Concentration of Standard Solution (ppm) Total Volume of Unknown Solution (mL) 10.00 10.00 10.00 Absorbance (au) 0.012 0.132 0.267 0.349 0.428 0.560 Absorbance (au) 0.289 0.296 0.281

Please provide the correct answers based on the following attached data.

Question 19 Silver nitrate can be purchased as high purity grade and does not require to undergo standardization against a secondary standard. True O False

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A solution of potassium permanganate of unknown concentration was analyzed against a standard of various concentrations. Refer to the following data set to answer the succeeding questions (MM KMnO4 = 158.034 g/mol). Table 1. Data for Standard Calibration Curve              KMnO4 Standard (grams/Liter) Absorbance at 525 nm 0.008 0.10437 0.158 0.20197 0.316 0.45288 0.474 0.68232 0.632 0.89361     Table 2. Data for KMnO4 Solution of Unknown Conc. Sample of Unknown Conc.  Absorbance at 525 nm Undiluted KMnO4 0.95423 Diluted KMnO4 (50% dilution) 0.46514   Which of the following linear equation for the standard calibration curve is generated fromTable 1?     y= 0.03231x – 0.74923     y= 0.04848x + 1.3179     y= 1.3179x + 0.04845     y= 0.74923x – 0.03231

Gold can be determined in solutions containing high concentrations of diverse ions by ICP-AES. Aliquots of 50.0 mL of the sample solution were transferred to each of four 100.0 mL volumetric flasks. A solution was prepared containing 10.0 mg/L Au in 20% H2SO4 and quantities of this solution were added to the sample solutions to give 0, 2.5, 5, and 10 mg/L added Au in each of the flasks. The solutions were made up to a total volume of 100.0 mL, mixed, and analysed by ICP-AES. The resulting data are presented in the following table. Added Au, mg/L Emission Intensity Count 12,568 19,324 26,622 40,021 0.0 2.5 5.0 10.0 Calculate the concentration of gold in the original sample.

B. The copper concentration in a contaminated salt sample was spectrometry. In the analysis, a 10.00-g sample containing an ar 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 ined by flame atomic absorption is transferred to a 250-ml 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).

VI. Flame Test Watch the following video: https://www.youtube.com/watch?v=kkBFG1mTSBk Record the color of the flame observed for each substance tested in the video. Solution Color Observed SrCl₂ NaCl KCI Solution LICI CuCl2 CaCl₂ Color Observed 1. Explain why colored flames are observed when elements are heated?

The method of standard additions was used to determine nitrite in a soil sample. A 1.00-mL portion of the sample was mixed with 26.00 mL of a colorimetric reagent, and the nitrite was converted to a colored product that produced a blank-corrected absorbance of 0.340. To 53.00 mL of the original sample, 1.00 mL of a standard solution of 1.00 x 10-3 M nitrite was added. The same color-forming procedure was followed, and the new absorbance was 0.500. What was the concentration of nitrite in the original undiluted sample? Concentration =  ______ M

2. The analytical ability of two lab technicians was compared by having each perform analyses for arsenic using the same method on samples having the same origin. For analyst A, s.d. = 0.12%, N=6; and for analyst B, s.d. = 0.06%, N-5. Do these results suggest a difference in the precision of the two chemists?

You were assigned to assay a product sample of milk of magnesia. A 0.600-g sample was reacted with 25.00 mL 0.10590 N H2SO4 . The excess unreacted acid in the solution required 13.00 mL of 0.09500 N NaOH when titrated to reach the methyl red end point. Determine the dosage strength of the product in terms of % Mg(OH)2 content. Type your answer in 2 decimal places, numbers only.

Which among these is the most important piece of data in a gravimetric analysis?   Mass of analyte   Mass of weighing form   Mass of crucible   Mass of precipitating agent

Nitrite ion, NO2-, is a preservative for bacon and other foods, but it is potentially carcinogenic. A spectrophotometric determination of NO2- makes use of the following reactions: A 5.00 cm cell was used to measure absorbance. Here is an abbreviated procedure for the determination.  1. To 50.0 mL of unknown solution containing nitrite is added 1.00 mL of sulfanilic acid solution.  2. After 10 min, 2.00 mL of 1-aminonapthalene solution and 1.00 mL of buffer are added. 3. After 15 min, the absorbance is read at 520 nm in a 5.00-cm cell.  The following solutions were annaylzed:  A. 50.0 mL of food extract known to contain no nitrite(that is a neglible amount); final absorbance =0.153 B. 50.0 mL of food extract suspected of containg nitrite ; final absorbance= 0.622 C. Same as B, but with 10 microliters of 7.50x10^-3 M NaNO2 added to the 50.0 mL sample; final absorbance= 0.967 a) Calculate the molar absorptivity of the colored product. Remember that a 5.00 cm cell was used  b) How many…

An sample of eggshell that weighs 1.0014g and is 51μm thick is titrated with disodium EDTA. A solution of the 1.0014g sample and 30 mL of HCl is vacuum filtered after being mixed. The product of the filtration is added to a 250mL volumetric flask and is diluted by being filled to the 250 mL mark with deionized water. 10 mL of this diluted mixture is mixed with EBT indicator and titrated with 0.05 M disodium EDTA. It takes 12.3 mL of disodium EDTA to notice a change in color. What percent mass of calcium is in the eggshell?

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Identify and explain the mistakes made in the following laboratory protocols:  A 1250 mg sample of NaOH was weighed using an analytical balance. The pellets were directly transferred in the balance pans, pellets were gradually added until the reading of the balance was near to 0.2000 mg.

Gold can be determined in solutions containing high concentrations of diverse ions by ICP. Aliquots of 50.0 mL of the sample solution were transferred to each of four 100.0 mL volumetric flasks. A solution was prepared containing 10.0 mg/L Au in 20% H2SO4, and quantities of this solutions were added to the sample solution to give 0, 2.5, 5 and 10 mg/L added Au in each of the flask. The solutions were made up to a total volume of 100.0 mL, mixed and analyzed by ICP. The resulting data are presented in the following table: Added Au (mg/L) Emission Intensity (Counts) 0.0 12568 2.5 19324 5.0 26622 10.0 40021 a) Attach an excel graph for the determination showing the X intercept. b) Calculate the concentration of gold in the sample, report with its uncertainty. c) The known concentration of gold in the sample is 8.51 mg/L. Test the hypothesis that your result is equal to this value at the 95% confidence level. l

You created a standard curve and calculated the slope to be 66.41. After synthesizing your copper network, you weighed 0.052 grams of your copper product, worked it up with nitric acid, buffer, and ammonia and added it to a 25 mL volumetric flask. Then, you measured the absorbance of your solution and received a value of 0.29. What is the % mass of copper in your product?

You want to make a solution of the primary standard sodium oxalate. It has a molecular mass of 133.999 g/mol (no error). Your analytical balance has an error of 0.2 mg. You add some weighing paper to the balance and it reads a mass of 0.23626 g. You then add sodium oxalate onto the weighing paper until the mass registers as 2.8539 g. You carefully transfer this to a 250.0 ml volumetric flask with an error of 0.1 ml and dissolve the sodium oxalate in a sufficient volume of water. What is the concentration of the oxalic acid (in M) and what is the absolute error (also in M).

1. A student performed this experiment and obtained the following concentration values: 0.02813 M, 0.02802, and 0.02788 M a. what is the mean concentration? b. what is the standard deviation of these results? 3. how would the following errors affect the concentration of Cl- obtained in question 2b? give your reasoning in each case. a. the student read the molarity of AgNo3 as 0.02104M instead of 0.02014M b. the student was past the endpoint of titration when he took the final buret reading.

In this experiment, the mass of pure copper provided is 0.491 gram, and then it was dissolved in nitric acid. An ammonia solution was added into it and transferred to a 100mL volumetric flask and dilute to 100ml with distilled water. This is the original standard solution. Then a diluted solution was prepared by adding 11 mL original standard solution to a 100ml volumetric flask and diluting to 100ml with distilled water. Please calculate the copper molarity of the diluted solution.