Chemistry

Problem

An aqueous mixture is 0.020 M in Al

^{3+}

and 0.020 M in Mn

^{2+}

. Given

K_{sp}(\text{Al(OH)}_3)=3.0\times10^{-34}

and

K_{sp}(\text{Mn(OH)}_2)=2.0\times10^{-13}

, calculate the minimum pH required to remove 99.9 % of the Al

^{3+}

while keeping the precipitation of Mn

^{2+}

below 1.0 %. State the pH to two significant figures.