posted by ralph .
The pH of a Ba(OH)2 solution is 10.66. What is the hydroxide concentration? If the solution volume is 125ml, how many grams of Ba(OH)2 have been dissolved?
pH = 10.66
pOH = 14 - 10.66 =3.34
(OH^-) = 10-3.34 = 4.57 x 10^-4 M
Actualy, Ba(OH)2 is rather soluble BUT it does have a Ksp in my books. I assume we are to assume it is soluble.
If (OH^-) = 4.57 x 10^-4 M, then [Ba)OH)2] is 1/2 that or 2.28 x 10^-4 M.
M = mols/L. You know M and L, calculate mols.
Then mol = g/molar mass. You know mol and molar mass, calculate grams.
Check my work carefully.