The unknown tablet is prepared for analysis in two steps. The tablet is crushed
ID: 503701 • Letter: T
Question
The unknown tablet is prepared for analysis in two steps.
The tablet is crushed into a powder and then dissolved into a 250 mL volumetric flask with dilute acetic acid. A diluted powder solution is prepared by transferring 25.00 mL of the original powder solution into a 50 mL volumetric flask and diluting to volume with dilute acetic acid.
Then 1.00 mL of the diluted powder solution is added to each of the standard addition flasks; each flask has a total volume of 10.00 mL.
The unknown's riboflavin concentration in the standard addition solutions is determined to be 1.21 ppm. What is the riboflavin concentration (ppm) in the unknown powder solution?
Explanation / Answer
Tablet----------->250 mL ----(10)---------->25mL----(2)------> 50mL---(50)----> 1mL----(10)-------> 10 mL
The numbers on the arrow are the dilution factors.
The riboflavin concentration in the standard addition solutions is 1.21 ppm.
Let us calculate the dilution factor:
1.21 ppm x 10 (10 mL volume)x 50 x 2 (25 mL diluted to 50 mL) x 10 (25 mL was taken from 250 mL).
So the amount of riboflavin in the tablet is:
1.21x10x50x2x10=12100 microgram = 12.100 mg (1mg = 1000 microgram)
The riboflavin concentration (ppm) in the unknown powder solution is (12100/10)
= 1210 ppm
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