How many grams of pure, solid naoh are required to make 400 ml of 0.1m naoh solution? express your answer to 2 significant figures,

e. g. 3.3 g?

In this question, you want to make 400 ml of 0.1m NaOH solution. The amount of NaOH in mol should be:

molar = mole of NaOH/l of water

0.1m = mol of NaOH / 0.4l

mol of NaOH = 0.1 * 0.4 = 0.04 mol

The molecular weight for NaOH should be 40g/mol. Then the amount of NaOH in grams would be: 0.04 * 40 (g/mol) = 1.6 grams