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- In the Analytical Chemistry laboratory, one of the B.Sc student Ms. Fatma wanted to analyze the presence of Iron(II) ion in the water samples collected from Sohar Industrial Area in the Sultanate of Oman and analyzed by Spectrophotometric method. (1) 250.00 mL of this water sample (Solution A) known to contain unknown amount of FeSO4. She has diluted Solution A by a dilution factor 10 to make 250.00 mL solution, which she labeled Solution B. Using Spectrophotometer, she has measured the absorbance value (0.642) for Solution B at 508 nm using 1.00 cm cell (cuvet). The molar absorptivity value for Fe2* ion at 508 nm is ɛ508 = 30.8 M-1cm1. (i) What volume of the solution A did she require to make the 250.00 mL of Solution В? (ii) in (i)? What instrument should she use to transfer the volume of the Solution A calculated (ii) Concentration of FeSO4 in Solution B. (iv) Concentration of FeSO4 in Solution A. Mass of FeSO4 in Solution A (Show your calculation) (v)2. Quantitative analysis student Analytical analyzed an ore sample for its lead content and obtained a mean of 4.75% Pb for five measurements. If the certified true value is 4.50%, what is the (a) percent error? (b) percent accuracy?2) As an example of precision and accuracy of data, suppose the % carbon in a single compound has been measured thrce separate times by 2 different students. The theoretical % carbon is 21.34%. Student 1: trial 1:26.11%, trial 2: 26.24% trial 3: 25.92 %, Avg - 26.09 Student 2: trial 1: 20.35%. trial 2: 22.64 % trial 3: 19.79 %. Avg = 20.93 a) Which student had the more precise data and how can you tell? b) Which student had the more accurate data and how can you tell? 3a) Calculate the % error of Student 1 data in problem 2 above. Show all work below. WATCH SIG FIGS
- 1. a. Calculate the mass of BaSO4 required to make 50.00 mL of a 0.1500 M solution. b. Calculate the absolute uncertainty in the molar mass of BaSO4. c. Calculate the absolute uncertainty in the concentration, assuming that the balance is calibrated and precise to ±0.1 mg and that the volumetric flask is calibrated and precise to 0.05 mL.The standard solution is prepared by dissolving a known mass of zinc pellets with conc. HCl. The solution is then neutralized, transferred into a 250 mL volumetric flask and filled to the calibration mark. If 0.9809 g of Zn was weighed using an electronic balance with a relative uncertainty of ± 0.01 % and the 250 mL volumetric flask has a known relative uncertainty of ± 0.06 %, what would be the absolute uncertainty of the concentration of the solution? The molecular weight of the zinc pellets is 65.39 g/molIn analytical chemistry, what is a standard method? Include any sources you used to answer this question. Give an example of a standard method, and the reference for it. 2.
- 0.3414 grams of sample (crushed aspirin tablet) was weighed and dissolved in 25 mL ethanol. This solution was transferred into a 100 mL volumetric flask and filled to the mark with deionized water. 20 mL of the solution was filtered through a 0.22 μm pore filter and 503 μL of the filtered sample solution was diluted so, that the final volume of the solution was 12 mL. This sample solution and calibration solutions with known concentration of acetyl salicylic acid (ASA) were injected (injection volume 20 μL) into a HPLC and the following peak areas were measured (expressed as averages from three separate chromatographic runs): Solution Cal 1 Cal 2 Cal 3 Cal 4 Cal 5 Sample Structure of ASA: C(ASA) (mg/L) 0 OH B 53.5 105.9 140.9 195.4 247.4 Average weight of the tablet was estimated as 591.9 mg. What is the mass of ASA in one tablet? Please give the answer with 4 significant digits. Be sure you present the result with units! Peak area (mA.s) 4995 9953 12941 17271 22179 10467.3Which of the following is true regarding method validation? I Method validation is an important requirement in the practice of chemical analysis. Il Method validation can only be done in collaboration with other laboratories. III Validation is confirmation, through the provision of objective evidence, that the requirements for a specific intended use or application have been fulfilled. Select one: O a. I only O b. I and Ill only O c. I, II and III Q O d. I and II onlyEight replicate measurements were made on a test solution producing the following results for the concentration of sodium ion (mg/L): 63.91, 65.92, 69.98, 64.24, 65.45, 65.82, 66.51, 65.11. The value 69.98 is an outlier suspect. A Q-test at 95% confidence level will lead to this conclusion with respect to the suspect value: O Should be thrown away Should not be thrown away There is not enough data to draw a conclusion None of the above
- 7. A procedure for measuring the amount of creatinine in blood was applied to a standard blood sample and the following results were produced: 0.787, 0.812, 0.796, 0.739, 0.802, and 0.823 mg/dL. a) Can any of the data points be rejected by the Grubbs test? b) What is the 95% confidence interval for the data?1. (a) A solution of NaCl is prepared by dissolving 0.0056 g NaCl with enough H2O in a volumetric flask to yield a final volume of 10 mL. Assuming a standard (0.1 mg) analytical balance and class A glassware is employed, calculate the concentration of the solution (M) and its corresponding error. The atomic weights of Na and Cl are 22.98976928(2) and 34.45(1), respectively (the number in parentheses indicating the error in the last digit). (b) What would the error be if a 1mL transfer pipet was employed (10x) rather than the 10 mL volumetric flask?3. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is a. 500 mg b. 250 mg c. 60 mg 4. The method described above is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative error resulting from a 0.4-mg loss is not to exceed a. -0.1% b. -0.8%