69 Grade Print Calculator Periodic Table e Question 2 of 2 A Sapling Learning Li

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69 Grade Print Calculator Periodic Table e Question 2 of 2 A Sapling Learning Ligand x forms a complex with both cobalt and copper, each of which has a maximum absorbance at 510 nm and 645 nm, A 0.281-g sample containing cobalt and co was dissolved to a volume of 100.0 mL. A solution containing ligand X was a to a 50.0 sample solution and diluted to a final volume of 100.0 mL. The measured absorbance of the unknown solution was 0.434 at and at nm, when measured with a 1.00-cm cell. The molar absorptivities of the cobalt and copper complexes at each wavelength are shown in the table below. Wavelength Molar Absorptivity (e, M-1cm M. nm Co Cu 37103 510 5627 1264 17840 645 What is the concentration of cobalt and copper in the final diluted solution? Number Number Co Cu What is the weight percent of cobalt (FM 58.933 g/mol) and copper (FM 63.546 g/mol) in the 0.281-g sample? wt Cu wt Co e Previous 8 Give up s view solution 2 checks Answer e Next l Exit

Explanation / Answer

Suppose concentration of Co is x and concentration of Cu is y is diluted solution.

Two mathematical equation can be made with the given values.

37103x + 5627y = 0.434

1264x + 17840y = 0.317

solve these two equations to get the value of x and y

x = [Co]= 9*10^-6 M

y = [Cu] = 1.7*10^-5 M

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Concentration in metal in 50mL aliquote

[Co]= 2 *9*10^-6 M = 18 *10^-6 M

[Co] = 18 *10^-6 M * 0.1L = 18*10^-7 moles

        = 18*10^-7 moles * 58.933g/mol =0.106*10^-3 gm

[Cu] = 2* 1.7*10^-5 M = 3.4 *10^-5 M

         = 3.4 *10^-5 M * 0.1L= 3.4 *10^-6 moles

         = 3.4 *10^-6 moles * 63.546g/mol = 0.216*10^-3 gm

wt % of Co = (0.106*10^-3 gm/0.281 ) *100 = 0.038%

wt % of Cu = (0.216*10^-3 gm/0.281) *100 = 0.076 %

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