# Molar Absorptivity

hello,

I am having difficulty with these problems and am unable to figure it out. help would be appreciated.

A yellow dye, FD&C yellow 3 is used in candy coatings. A 1.50 x 10^-5 M solution of this dye has absorbance of 0.209 lambda max.

Calc. molar absorptivity,epsilon (e), of the dye at this wavelength, assuming sample cell of 1.0cm pathlength.

The yellow dye from one piece of candy is extracted into 10 mL of water and diluted to 50 mL with water. The absorbance of the diluted solution is 0.496 at its lambda max. Calc. the concentration of the dye in the diluted solution.

Calc the number of grams of this dye in the coating of one piece of candy (MW of dye = 271 g/mol).

*i kind of understand the concept of these questions but im having difficulty solving it out.

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Is there equations in your book to calculate molar absorptivity, epsilon (e) and also what unit is lambda max, is there a somekind of conversion factors related to it?

Sunil

Tue, 2008-03-04 19:14

just use Beer's law

A = e bc

where A is absorbance

e is molar abosorbtivity

b is path length

and c is concentration

Chemistry Tutor

Tue, 2008-03-04 19:28