Question

Hi, I need help with answering these questions. Thank you.

1) What is the molar absorptivity of riboflavin (with units)? Assume that the cuvette has a pathlength of 1.00 cm and that the blank had an absorbance of 0.00.

Absorbance of Riboflavin at 445 nm y = 26587x R2 = 0.9994 Absorbance 0.00002 0.00004 0.00006 Concentration of Riboflavin (M)

2. If a sample of riboflavin with an unknown concentration had an absorbance of 0.597, what is the concentration of the sample?

3. A sample of riboflavin is prepared by crushing 5 tablets and dissolving them in enough water to create a 500.0 mL solution. The sample has an absorbance of 0.597. How many mg of riboflavin were in each tablet? MM of riboflavin = 376.37 g/mol

4. If a blank sample containing all the tablet ingredients except for riboflavin had an absorbance of 0.145, then what would be the concentration of our sample with an absorbance of 0.597?  

Answer 1

Here beer Lambert's law has been used to solve the problem
Je maa allovi Using the Beex- lambert equation, A= Ecl . A = Absorbance & = molax absoaptivity e = path length ( = 100 cm in given c = concentration of selute in the solution ering the graph equation y = 26587a - Hore y = A = Absorbanu x = c = concentration of Riboflavin Hence, compasing equation and , we get El = 26587 M' { as absoxbante has no unity & = 26587 M 26584 m = 26587 cm'm Tom Hence Molas riboflavin - 2657 cm 12 Hence molar akseperity of mboflawin = 2657 cri' Here given A=0.597 We have find concentration of sample = c = 2 By using the equation we get c= A = 2657 cm = 0.597 2657 cm x 1cm. 0.00022M

I let one tablet contain a moles of axboflavin Hande, concentraten e sooml solution containg s & tablett = ( 57 ) M = 100 M the equation , can get Now using A=&le Here we have considered that 0.597 = 26587 cm x 1cm X (10x) tablet have made of I pure riboflavin 0.597. - za 7 x= 2246410 26587 X lo 2.245 xios Heren on tablet contains R-248 x banoles of stoflovina ne (2-246 x 108 x 37 6.37) goons of inboflavia ie 0.000 3456 groms ise 0-8456 milligrams. 2456 miligrany I love absorbance of blank containing remaining material for ingedient I except aboflarn is 0.845 Abosband of sample = Absorboner by raboflava + Absorbence by demaining =Absos bona of riboftoin = 0.594 – 0,45 Now, wing the equation @ , en get CZ = 26587 cm tm x 1cm Here A = Absorbance of anboflavin - ingredient and blank = 0.452 0.452 = 1.700x105m