please help chemistry question

Question

If 3.0 g of sodium metal completely reacts with 43.2 mL of pure water (which is in excess), what is resulting molarity of the sodium hydroxide solution?

Answer 1

3 grams of Na means it is 0.13 moles of Na( to find the moles divide grams with the atomic mass of Na which is 23 grams)

2Na + 2H₂O ---------------- 2NaOH + H₂

2 moles of Na would produce 2 moles of NaOH, therefore 0.13 moles of Na would produce 0.13 moles of NaOH

to calculate the molarity of NaOH , 0.13 moles divided by the volume of solution 43.2 mL which is 0.0432 liters therefore the molarity of the solution is 0.13 moles/0.0432 = 3 moles/liter