Question

How many milliliters of a 15.0%, by mass solution of {KOH}(aq) (d = 1.14 g/mL) are required to produce 25.0 L of a solution with pH = 11.60?

Answer 1

Calculate molarity of KOH solution.
That is 1.14 g/mL x 1000 mL x 0.15 = approximately 175 grams KOH. So mols KOH = 175/56 = about 3 M.

Now go to what you want to prepare. You want pH = 11.60 which is pOH or 2.40 or (OH^-) = about 0.004 M.

Now mL(soln 1) x M(soln 1) = mL(soln 2) x M(soln 2)
You need to redo the whole problem because I estimated molar masses and rounded here and there to make it quicker to calculate. The answer is approximate only so you need to put in the exact values.

Answer 2

thanks alot !! =)