Question

Each of the insoluble salts below are put into 0.10 M hydrobromic acid solution. Do you expect their solubility to be more, less, or about the same as in a pure water solution?

lead bromide

iron(II) sulfide

silver iodide

barium fluoride

Answer 1

HBr acid:

lead bromide

--> PbBr2 --> Pb+2 + 2Br-

since HBr is added, ther eis shift in equilbiirum, Br- is present as common ion, therefore PbBr2(s) increases, solubility decreases

iron(II) sulfide

FeS = Fe+2 + S-2

S-2 + H+ = HS-

thjen, there is shift towards even more S-2 production, so FeS(s) must go into solution

FeS(s) increases

silver iodide

AgI <-> Ag+ + I-

presence of HBr- will precipitate Ag + Br- = AgBr

therefore, AgI will go to soluble Ag+ + I- to counterbalance the difference

AgI increases in solubility

barium fluoride

BaF2 = Ba+2 + 2F-

addition of H+ increases:

F-+ H+ = HF

therefore, shift goes from solid BaF2 to ionic Ba+2, 2F- , this increases solubility