Calculate the mass of sodium hydroxide needed to prepare 500 mL of a 0.10 M solution. I'm pretty sure the answer is 2 grams, but how do I get to that?

Answer 1

mols NaOH = L x M = 0.500 L x 0.10 M = 0.05 mols NaOH.

Remember mols = grams/molar mass
Rearrange to obtain
grams = mols x molar mass = 0.05 mols x (40.0 g/1 mol) = 0.0500 x 40.0 = 2.0 g