Question

How many grams of K2Cr2O7 (Potassium dichromate) must be used to make 250 ml of a0.125 M solution?

Answer 1

How many mols do you need? That's mols K2Cr2O7 = M x L = ?
Then mols = g/molar mass. You know mols ad molar mass. solve for grams.

Answer 2

0.10622g