In experiment 7, you used the method of standard additions (volume of unknown wa
ID: 840321 • Letter: I
Question
In experiment 7, you used the method of standard additions (volume of unknown was 10.0 mL) and fluorescence spectroscopy to measure the amount of quinine (C20H24N2O2, MW = 324.43 g/mol) in tonic water. 1.00 mL of tonic water was added to a 50.0 mL volumetric flask and diluted to the mark with distilled water. A 100 ppm quininesulfate ((C20H24N2O2)2?H2SO4?2H2O, MW = 782.97 g/mol) solution was used as the standard. Assuming that your original (undiluted) sample contained 142 ppm of quinine sulfate, calculate the amount in ppm of quinine in the sample.
Explanation / Answer
Concentration in undiluted sample=142mg/L
Dilution factor=50(from 1-50mL)
concentration in diluted sample=142/50=2.84mg/L or ppm