A yellow dye, FD&C yellow 3, is used in some candy coatings. A 2.4*10^-5 M solut

Question

A yellow dye, FD&C yellow 3, is used in some candy coatings. A 2.4*10^-5 M solution of this dye has an absorbance of 0.418 at its Amax. Show all work.

a. Calculate the molar absorptivity,E, of the dye at this wavelength, assuming a sample cell with a 1.0 cm pathlength.

b. The yellow dye from one piece of candy is completely extracted into 10.00 mL of water and diluted to 100.00 mL with water. The absorbance of the diluted solution is 0.556 at its Amax. Calculate the concentration of the dye in the diluted solution.

c. Calculate the number of grams of this dye in the coating of one piece of candy (MM of dye=271 g/mol).

Explanation / Answer

a. Absorbance, A=E*C*l

C is the concentration and l is pathlength in cm

Therefore E=A/(C*l), where A=0.418, C=2.4E-5M and l=1cm.

E=0.418/(2.4E-5*1)=0.1742E5M-1cm-1.

b. Here A=0.556

we know that E= 0.1742E5M-1cm-1.

Therefore C=A/(E*l)= 0.556/(0.1742E5*1)=3.1917E-5M.

c. Weight =(Conc*Mol.wt*Volume)/1000

Here weight=(3.1917E-5*271*100)/1000=86.495E-5g

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