posted by Hunter .
Describe in detail a way of preparing 500 ml of solution that is 0.02500 M in sodium ions. Start with solid sodium sulfate decahydrate.
You want 0.025 M Na^+.
You want 0.025 mols Na/L.
How many mols do you want? That is M x L = 0.025 M x 0.500L = ? mols.
If you weigh Na2SO4.10H2O you will want 1/2 mols of Na2SO4 (because there are 2 Na^+ in 1 mol of the salt). Then convert mols Na2SO4.10H2O to grams.