How many grams of KOH must be dissolved in one litre of solution to give it a pH value of 12?

Answer 1

pH + pOH = 14
Solve for pOH.

pOH = -log(OH^-)
Solve for OH^-

How many moles KOH do you need?
moles KOH = M x L = ??
Then moles = grams/molar mass
Solve for grams.
.

Answer 2

PH PoH =14
PoH=14-12=2
PoH=-log[OH]
OH=log~[-2]
OH=O.O1
NOW,
MOLARITY=gm/litre|AT.wt
O.O1=gm/1|57
gm=0.57
hence mass of kOH IS O.57gm.