[cyberdx16]

heres the question, Calculate the pH [H], [OH] for a slution that contains 2.75g of Ba(OH)2 in a 2.5L solustion of water.

so far i know the Molarity is 6.4e-3, and i know that Ba(OH)2 is a weak base so it will not completely dissociate in H20. Also what is the balanced equ for this reaction?

[Borek]

Ba(OH)₂ is a strong base.

[cyberdx16]

Ba(OH)₂ is a strong base.

it is among the few 2A hydroxides that are not strong bases

[Borek]

1^st, please check this page for HaOH/KOH strength explanation:

http://www.chembuddy.com/?left=FAQ

Same book lists stability constant for BaOH⁺ as 10^0.6 - it translates to pKb = 0.6. Second stability constant is not listed, which most likely means that it is much smaller (read: base is much stronger). pKb = 0.6 is a border case - not as strong as - say - KOH, but hardly weak. As Ba(OH)₂ is weakly soluble it is usually not concentrated enough to be not fully dissociated. In your case it is dissociated in over 97%.

Your molarity is OK, you may safely assume 100% dissociation, reaction is simple dissociation.