## Chemistry: The Central Science (13th Edition)

$pH \approx 11.472$
1. Convert $10^{-6}g$ of $Mn^{2+}$ to number of moles: $mm(Mn) = 54.94 g/mol$ $n(moles) = \frac{mass(g)}{mm}$ $n(moles) = \frac{10^{-6}}{54.94}$ $n(moles) = 1.82 \times 10^{-8}$ $10^{-6} g/L (Mn)= 1.82 \times 10^{-8} M$ 2. Use the Ksp formula to find $[OH^-]$ $Ksp = [Mn^{2+}][OH^-]^2$ $1.6 \times 10^{-13} = [1.82 \times 10^{-8}][OH^-]^2$ $8.79 \times 10^{-6} = [OH^-]^2$ $[OH^-] = 2.965 \times 10^{-3}$ 3. Find the pOH: $pOH = -log[OH^-]$ $pOH = -log(2.965 \times 10^{-3})$ $pOH = 2.528$ 4. Calculate the pH: $pH = 14 - pOH$ $pH = 14 - 2.528$ $pH = 11.472$