0.112 mol / 3470 L = 3.17×10-5 M
Hydroxide concentration is twice that: 6.34×10-5 M
pOH = 4.2
Doesn't look right.
2 [OH-] = [Ca(OH)2]
Quite the opposite.
Christ I'm stupid. I had been up for ~24 hours when I tried to solve it.
Of course it is 2 [Ca(OH)2
] = [OH-
] and then I do get around twice what OP got using the same method otherwise. Thanks, Borek.