ABSORBANCE PHOTOMETRY ADVANCE STUDY ASSIGNMENT Name 1. A solution is prepared by

Question

ABSORBANCE PHOTOMETRY ADVANCE STUDY ASSIGNMENT Name 1. A solution is prepared by dissolving 0.1896 grams of FD&C; Red #40 in water to produce 2.500 Liters of solution. Given that the molecular formula ofRed 40 is CINH Sios, determine the molarity of this stock solution 2. 25.00 mL of the dark red stock solution described question #1 is transferred to a volumetric flask and diluted with water to a total final volume of 100.00 mL. a. how many moles of Red 40 are in the 25.00 mL sample that was transferred? b. After the dilution, what is the molarity of the Red 40 moles in the 100.00 mL of solution? note: the preceding problem (n2) is a dilution calculation. A convenient formula for calculating concentrations after dilution is Mrvi M2v, where Mi and Vi are the molarity and volume of the concentrated solution, respectively, and Mr and 2 are the molarity and volume of the dilute solution. 3. a. The solution described in problem #2 is placed the Based on the calibration curve shown in be? Note: on the next page, would you predict the absorbance to not just like the example given in the discussion, the absorbance should be calculated, curve estimated from the graph. Notice that the slope and intercept of the calibration are provided in the figure on the next page. Absorbance

Explanation / Answer

2s2Ans 1.

Molarity = No. of moles of solute / Volume of solution in litre .

no. of moles of Red 40 = Given mass / molar mass

Molar mass of C18H14N2S2O8 = 450.44 g/mol

No. of moles = 0.1896/ 450.44 = 0.00042 moles

molarity = 0.00042/ 2.5 = 0.00017 M

So the molarity of the solution is 0.00017 M.

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