In a metallurgy process, aqueous Fe2+ ions at an initial concentration of 0.010M are removed by precipitating iron(II) hydroxide, Fe(OH)2, through pH adjustment. The precipitation is carried out at 25∘C with negligible volume change.
Ksp[Fe(OH)2]=7.9×10−17
Answer the following questions about the conditions required for precipitation.
(a) Determine the maximum pH at which the solution can be maintained before Fe(OH)2 begins to precipitate from a 0.010M Fe2+ solution at 25∘C. Show your calculations.
(b) Describe qualitatively how further increasing the pH beyond the value calculated in part (a) will affect the extent of precipitation, and explain the underlying chemical reasoning.