25.00mL of the dark red stock solution described question #1 is transferred to a

Question

25.00mL of the dark red stock solution described question #1 is transferred to a volumetric flask and diluted with water to 100.00mL how many moles of red 40 are in the 25.00 mL sample that was transferred? After the dilution, what is the molarity of the red 40 in the 100.00mL of solution? The preceding problem (#2) is a dilution calculation. A convenient formula for calculating concentration after dilution is M-1V-1=M-2V-2, where M-1 and V-1 are the molarity and volume of the concentrated solution, respectively, and M-2 and V-2 are the molarity and volume of the dilute solution. The solution described in problem#2 is placed in the spectrophotometer. Based on the calibration curve shown on the next page, what would you predict the absorbance to be ? Note: like the example given in the discussion. The absorbance should be calculated, not just estimated from the graph. Notice that the slope and intercept of the calibration

Explanation / Answer

Since the molarity is not given in the problem, hence i have assumed the previous molarity as M1

Since the number of moles will be remain constant

M1V1 = M2V2

M1 * 25 = M2 * 100

M2 = M1/4

Number of moles of Red 40 = 25/1000 * M1/4 = 6.25 M1 m moles

Molarity will be equal to M1/4 where M1 represents the old molarity

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