How many grams of NaOH are present in 2000 mL of 0.1 M NaOH? The molecular mass of NaOH is 40 amu

The key to solving this problem is to get as many units the same as possible then convert from there, and to remember that is moles per liter.

So, 2000 mL = 2 L, 0.1 M = 0.1 mol/L. Instead of thinking about molecular mass, think molar mass, so NaOH is 40 g/mol.

Now, all we have to do is multiply liters by molarity (mol per liter), 2 L x 0.1 mol/L. Liters cancel, leaving us with 0.2 moles of NaOH. Now we multiply moles by the molar mass of NaOH, 0.2 mol x 40 g/mol. Moles cancel, leaving us with an answer of 8 grams of NaOH.