Question
The average pH of open ocean water is 8.1. What is the maximum value of [Fe3+] in pH 8.1 seawater if the Ksp of Fe(OH)3 is 1.1*10^-36?
Answers
DrBob222
Fe(OH)3 ==> Fe^3+ + 3OH^-
pH = 8.1
pH + pOH = pKw = 14
Therefore, pOH = 14-8.1 = ?
pOH = -log(OH^-) and
(OH^-) = ?
Ksp = (Fe^3+)(OH^-)^3
Substitute Ksp and OH^- from above into Ksp expression and solve for Fe^3+.
pH = 8.1
pH + pOH = pKw = 14
Therefore, pOH = 14-8.1 = ?
pOH = -log(OH^-) and
(OH^-) = ?
Ksp = (Fe^3+)(OH^-)^3
Substitute Ksp and OH^- from above into Ksp expression and solve for Fe^3+.