posted by Chemistry Confused .
What must be the pH of a solution that is 0.049 M Fe3+ to just cause Fe(OH)3(s) to precipitate?
Fe(OH)3 ==> Fe^+3 + 3OH^-
Ksp = (Fe^+3)(OH^-)^3
Substitute 0.049 for (Fe^+3) and solve for OH^-. Convert to pOH then to pH.