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April 30, 2016

# Homework Help: chemistry

Posted by David on Tuesday, February 8, 2011 at 1:22am.

Fish-liver oil is a good source of Vitamin A. When 0.1232 g of fish liver oil is dissolved in 500. mL of solvent, an absorbance of 0.724 is recorded. When 0.00167 g of Vitamin A is dissolved in 250. mL of solvent, an absorbance of 1.018 is recorded. Calculate the mass percent of Vitamin A in fish-liver oil.

I have no idea where to go with this for an equation. any assistance would be greatly appreciated.
• chemistry - DrBob222, Tuesday, February 8, 2011 at 11:50pm

A = kc
A = 1.018 for 250 mL.
1.018 = k*0.00167
Solve for k

For the unknown, assuming a straight line relationship, we want to compare the same volume of material; therefore, if we took 0.1232 g fish liver oil and dissolved it in 250 mL volume, the A would be twice that in the problem or 0.724*2

0.724*2 = k(from above)*C.
Solve for C which will be grams/250 mL.

%vitaminA = (g vit A in the sample/0.1232)*100 = ??% vit A.