... testing is to determine the %w/w of benzoate in the sample.
The entire sample was dissolved in a 100.0 mL volumetric flask (v.f.). In order to obtain an absorbance within range, this sample was diluted using an aliquot of 5.0 mL diluted to 100.0 mL. Note that this represents a dilution factor (DF) = 20.
A series of 4 standards are made using a stock solution of sodium benzoate. The stock standard used 0.1809 grams of sodium benzoate in a 1.0 L v.f. A blank solution is also prepared.
blank: 0 mL stock in 100.0 mL v.f. A225 = 0.37
wrk std 1: 5.0 mL stock in 100.0 mL v.f. A225 = 0.55
wrk std 2: 10.0 mL stock in 100.0 mL v.f. A225 = 0.75
wrk std 3: 15.0 mL stock in 100.0 mL v.f. A225 = 0.93
wrk std 4: 20.0 mL stock in 100.0 mL v.f. A225 = 1.08
wrk smp: A225 = 0.78
To help you get started - determine the concentration of your stock standard using the gravimetric conversion between sodium benzoate (C6H5COONa) and the benzoate ion (C6H5COO-).
Answer the [benzoate] (ppm) to 2 decimal places