Question

An unknown amount of riboflavin (100 tablets) was dissolved in 1 liter of water, one milliliter of the solution obtained was diluted to one liter. The measured fluorescence of the resulting solution was 42 units. A pattern containing 9.05 mg / liter of riboflavin gave a reading of 32 units. What is the average amount of milligrams of riboflavin in each tablet?

Answer 1

Concentration of pattern = 9.05 mg/L

fluorescence of pattern = 32

absorptivity of riboflavin = (fluorescence of pattern) / (concentration of pattern)

absorptivity of riboflavin = (32) / (9.05 mg/L)

absorptivity of riboflavin = 3.536 L/mg

fluorescence of final solution = 42

Concentration of riboflavin in final solution = (fluorescence of final solution) / (absorptivity of riboflavin)

Concentration of riboflavin in final solution = (42) / (3.536 L/mg)

Concentration of riboflavin in final solution = 11.88 mg/L

According to dilution law, we have the formula C1 * V1 = C2 * V2

where

C1 = concentration of riboflavin in original solution

V1 = volume of original solution = 1 mL = 0.001 L

C2 = concentration of riboflavin in final solution = 11.88 mg/L

V2 = total volume of final solution = 1 L

Substituting the values,

C1 * (0.001 L) = (11.88 mg/L) * (1 L)

C1 = (11.88 mg/L) * (1 L / 0.001 L)

C1 = (11.88 mg/L) * (1000)

C1 = 11880 mg/L

Total volume of original solution = 1 L

Total mass of riboflavin = (concentration of riboflavin in original solution) * (Total volume of original solution)

Total mass of riboflavin = (11880 mg/L) * (1 L)

Total mass of riboflavin = 11880 mg

number of tablets dissolved = 100 tablets

average amount of riboflavin = (Total mass of riboflavin) / (number of tablets dissolved)

average amount of riboflavin = (11880 mg) / (100 tablets)

average amount of riboflavin = 118.8 mg/tablet