if we have the equation BaSO4(s) = Ba2+ (aq) + SO4 2-(aq) and we add OH- which way would the equilibrium shift?

Question

i was just told that it shifts right but why?

Answer 1

If Ba(OH)2 were insoluble, then adding OH- would definitely shift the reaction to the right. The reason being that as you precipitate the Ba²⁺(aq), according to LeChatelier's principle, the reaction would shift toward the products. HOWEVER, Ba(OH)₂ is fairly soluble, so this would not be the case.

Not sure why someone told you it would shift to the right. At first inspection, I can't see why that would be the case. The added OH- can only react with one species, and that would be the aqueous Ba²⁺. As mentioned, that would form Ba(OH)₂ would would simply dissociate back to Ba²⁺ + OH^-.

Maybe someone else will weigh in and enlighten both of us.