Will fe(OH)3 precipitate from a buffer solution that is 0.60M CH3COOH and 0.10M CH3COONa, if the solution is also made to be 0.001 M in Fe3+? (Ksp of Fe(OH)3 = 6.8x10^-36
2007-04-22 06:11:21 · 3 answers · asked by Heavy-Metal123 3 in Science & Mathematics ➔ Chemistry
You can use the Henderson-Hasselbalch equation and the pKa for acetic acid to calculate the pH of the acetic acid/sodium acetate solution. From the pH, you can calculate the [OH-] concentration. Then, you can plug that hydroxide ion concentration and the iron ion concentration into the expression for Ksp, to determine whether the value is greater than or less than the Ksp. If it is greater, then Fe(OH)3 will precipitate.
It's not particularly freakin hard, it just requires several steps.
2007-04-22 06:24:32 · answer #1 · answered by hcbiochem 7 · 0⤊ 0⤋
The Henderson-Hasselbach equation is:
pH = pKa + lg( c(salt)/c(acid) ), pKa for acetic acid is 4,75.
pH = 4.75 + lg(0,1/0,6) = 3,97
pOH = 14 - pH = 14 - 3,97 = 10,06
[OH-] = 10^-10,06 = 8,71*10^-11 M
[Fe3+] * [OH-]^3 = 6,61*10^-34 that is more, than Ksp of Ferrum (III) hydroxydum.
So, it will precipitate.
2007-04-22 13:33:45 · answer #2 · answered by Anonymous · 0⤊ 0⤋
yes
2007-04-22 13:18:44 · answer #3 · answered by Matt G 5 · 0⤊ 0⤋