I have a 500mL flask, and I want to prepare 500mL of NaOH solution with a pH of 13.00. How many grams of Na OH do I need to put in the flask to arrive at this pH?

Answer 1

pH = 13. Convert to pOH from
pH + pOH = pKw = 14
Then convert OH^- from
pOH = -log(OH^-).
OH^- will give you moles/L. YOu want 500 mL so you want half of that number of moles. Then moles = grams/molar mass. You know moles and molar mass NaOH, solve for grams. Something close to 2.0 g perhaps.