An environmental chemist working for the Environmental Protection Agency (EPA) w

Question

An environmental chemist working for the Environmental Protection Agency (EPA) was directed to collect razor clams from a heavily-contaminated river superfund site and analyze them for cadmium (Cd2 ) content using graphite furnace atomic absorption spectrometry (GFAAS). The chemist freeze-dried the clams and processed them in a blender resulting in ~ 50 g of homogenized dry weight. A representative 69.00 mg sample was taken from the ~ 50 g dry material and dissolved in 100.00 mL of 0.1 M HCl to create a sample solution. Using the method of standard additions, the chemist prepared 5 standard solutions in 100.00-mL volumetric flasks, each containing 5.00-mL aliquots of the sample solution. Varying amounts of a 85.0 ppb (g ·L-1) cadmium standard were added to each of the flasks, which were then brought to volume with 0.1 M HCl. The solutions were then examined for their Cd2 content using GFAAS, resulting in the following absorbance data.

· Texas State University- X saplinglearning.com Standard Deviation Calculat C Chegg Study | Guided Solut+ | sapingleaming.com/ibiscms/mod/ibes/new.php?id-3974 1 50 arning Jump to.. View Profile macmillan leaming Graded HCI. The solutions were then examined for their Cd2content using GFAAS, resulting in the following absorbance data. Logout Sample Vol. (mL) 5.00 5.00 5.00 5.00 5.00 Cd2+ Standard Vol. (mL) 0.00 2.50 5.00 7.50 10.00 Cd2+ Standard Mass (g) 0.000 0.213 0.425 Absorbance 0.080 0.119 0.163 0.200 0.241 Policies: Homewo You can check your answers You can vicw solutions whc give up on any question You can keep trying to answ until you get it right or give 0.638 0.850 Determine the amount of Cd2 per gram of dry clam weight. Express your final result as weight percent giallis ur Cd per yl dlluf diy dani Illultiplied by 100). Auditiunally find theabsulut unrtainty standard eviation) and the 95% confidence interval of the measurement. A list of Student's t values can be found here. Report the absolute uncertainty and 95% confidence level with two signiticant figures. driswer in your question for attempt at that answer Number Numbcr Scroll down to view the entire question wt % ±uncertainty - 110 eTexthook % O Ilelp With This Topic Number wt %±95% confidence interval Web Help & Videos 98 Hint O Previous Give up & View Solution check Anewer ) Next Exit - Technical Support and Bu Type here lo searchi @ wI

Explanation / Answer

Answer:

For every sample, we can do following calculation;

Sample 1 = 0/5*100= 0

Sample 2= 2.50/5*100= 50%

Sample 3= 5/5*100=100%

Sample 4= 7.50/5*100= 150%

Sample 5= 10/5*100= 200%

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