Question

In the laboratory you will be provided with a 1.0 x 10-5 M primary stock solution of fluorescein (MW=332.31g/mol). The calibration curve should include a blank, 0.025, 0.05, 0.075, 0.10, 0.15, and 0.25 micromolar fluorescein solutions. Since you will be using 25 mL volumetric flasks and the smallest mass that you can weigh out is 1.0 gram you will need to prepare a secondary stock. What concentration of secondary stock should you prepare?
To prepare 100 mL of secondary stock, what weight of primary stock do you need to weigh out? Give your answer in grams.