Starting with 14.6 ml of 4.20 x 10-2 M AgNO3...?

Question

Starting with 14.6 ml of 4.20 x 10-2 M AgNO3, how many grams of KBr can be added to the solution before AgBr begins to precipitate ?

Answer 1

Not much!

Look up Ksp of AgBr.

When precipitation begins, [Br-] x [Ag+] = Ksp (definition) and you know [Ag+] = 4.20 x 10-2 M

So this tells you the concentration of Br- and hence of KBr.

Conc x volume = amount and, to finish off, amount(mol) x f.wt. = mass (g)