Question

The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 μL of the sample and injecting it into a cuvette already containing 2.00 mL of water (total volume is 2.00 mL + 100.0 μL). The absorbance value of the diluted solution corresponded to a concentration of 8.21×10−6 M . What was the concentration of the original solution?

Answer 1

And. Given,

            Initial volume of original sample = 100.0 uL = 0.100 mL

            Final volume of diluted sample = 2.000 mL + 0.100 mL = 2.100 mL

            Final concertation of diluted solution = 8.21 x 10^-6 M

Now, using    C1V1 (original solution) = C2V2(diluted solution)

            Or, C1 x 0.100 mL = 8.21 x 10^-6 M x 2.100 mL

            Or, C1 = (8.21 x 10^-6 M x 2.100 mL) / 0.100 mL

            Hence, C1 = 1.7241 x 10^-4 M

Therefore, concertation of original sample = 1.7241 x 10^-4 M