Manganite ore is an important copper ore mineral mined in the Kalahari Desert and can be leached with

sulphate solutions to selectively extract manganese. From these solutions, the manganese can be

recovered from the leachate by precipitation as a metal powder using hydrogen sulphide gas at

controlled $pH.$ If such a solution contains $44\mathrm{.}3\frac{g}{L}M{n}^{2+},$ calculate at which $pH$ should the precipitation

process be operated at to recover at least $95\%$ of the manganese at $25C$ using $1atm{H}_2{S}_{(g)}.$ Assume

unit activity coefficients.