金屬離子加鹼的沉澱 (precipitation)(20分)

i can see you using terms in English, so i assume that you can understand English as well.
i'm using English to answer; if you need Chinese explanation, just say so!

1.
4Fe(OH)2 + 2H2O + O2 ------> 4Fe(OH)3

2. though wikiepdia says so, i can't understand why iron(II) is colorless;
in my point of view, it should be iron(III) to be colorless, according to ligand-field theory.

this theory describes splitting of (d-)orbitals under influence of ligands, such as aqua (H2O) and hydroxo (OH(-)); as well as possibility of electron transition.
the d6 structure of iron(II) should allow excitation anyway, so photons are absorbed and color should be observed. in contrast, iron(III) has d5 structure. combined with weak-field ligands, d-d transitions are forbidden, so no color or very pale color should be observed.

it may relate to the oxygen or oxide ligand, though i have no idea for the exact reasoning.


3.
Pb: plumbate / tetrahydroxoplumbate(II) ion, [Pb(OH)4](2-); colorless; 鉛酸根離子
Zn: zincate / tetrahydroxoznicate(II) ion, [Zn(OH)4]2(2-); colorless; 鋅酸根離子
Al: aluminate / tetrahydroxoaluminate(III) ion, [Al(OH)4](-); colorless; 鋁酸根離子

Zn: tetraamminezinc(II) ion, [Zn(NH3)4](2+); colorless; 四氨合鋅(II) 離子
Ag: diamminesilver(I) ion, [Ag(NH3)2(+); colorless; 二氨合銀(I) 離子
Cu: tetraamminecopper(II) ion, [Cu(NH3)4](2+); deep blue; 四氨合銅(II) 離子