A 10.0 mL aliquot of a flouride sample solution was diluted to 250 mL in a volumetric flask. The F- concentration of this DILUTED sample was determined with a F- ion selective electrode and found to be 7.1 mg/L. What is the concentration of F- in the original, undiluted sample?
Ive done a bit of work on this and cannot figure it out. Help?
7.1 mg/L x (250/10) = ?
To find the concentration of F- in the original, undiluted sample, you can use the concept of dilution. Dilution is the process of adding solvent to a solution to decrease its concentration.
In this problem, you have a 10.0 mL aliquot of the original sample, which you diluted to a total volume of 250 mL in a volumetric flask. The concentration of F- in the diluted sample is given as 7.1 mg/L.
To determine the concentration of the original sample, you can use the equation:
C1V1 = C2V2
Where:
C1 is the concentration of the original sample (unknown),
V1 is the volume of the original sample (10.0 mL),
C2 is the concentration of the diluted sample (7.1 mg/L),
V2 is the final volume of the diluted sample (250 mL).
Rearranging the equation, we have:
C1 = (C2 × V2) / V1
Substituting the given values:
C1 = (7.1 mg/L × 250 mL) / 10.0 mL
C1 = (7.1 mg/L × 25)
C1 = 177.5 mg/L
Therefore, the concentration of F- in the original, undiluted sample is 177.5 mg/L.