how to prepare a 250 mL solution of .15 M K2SO4 with a volumetric flask

Answer 1

You need how many mols? That's M x L = ?mols K2SO4.

mols = grams/molar mass. You know molar mass and mols, solve for grams.

Here is how you do it. Weigh ? grams K2SO4, place in a 250 mL volumetric flask, add SOME water and swirl until K2SO4 is completely dissolved, then add water to the mark on the volumetric flask. Mix thoroughly.