24, Chrom (Cr)
Chromium, lat. chroma = Farbe |
Säure-Base-Verhalten:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Säure/Base-Verhalten der Chrom-Oxide: |
|
Reaktionen mit: |
HF 100% |
H2SO4 conc. |
HCl 20% |
CH3COOH 25% |
H2O |
NH3 25% |
NaOH 10% kalt |
NaOH 50% heiß |
NaOH liq. 400°C |
Cr2O3 |
CrF3↓ |
Cr2(SO4)3 |
CrCl3(aq) |
(CH3COO)3Cr |
Cr(OH)3↓ |
Cr(OH)3↓ |
Na3Cr(OH)6 |
Na3Cr(OH)6 |
NaCrO2 |
CrO3 |
|
|
H2Cr2O7 |
H2CrO4 |
H2CrO4 |
(NH4)2CrO4 |
Na2CrO4 |
Na2CrO4 |
Na2CrO4 |
|
Legende: |
Lösung |
|
Unlöslich |
|
sauer → neutral → alkalisch |
|
|
|
|
pKS-Werte von Säure-Base-Paaren (HA + H2O ↔ H3O+ + A-) : |
Säurename |
Formel |
pKS-Wert |
Basenname |
Formel |
pKB-Wert |
|
Chrom(II)-Ion |
Cr2+ |
10.0 |
Hydroxo-Chrom(II)-Ion |
Cr(OH)+ |
4 |
|
Chrom(III)-Ion |
Cr3+ |
3.95 |
Hydroxo-Chrom(III)-Ion |
Cr(OH)2+ |
10.05 |
Hydroxo-Chrom(III)-Ion |
Cr(OH)2+ |
4.4 |
Dihydroxo-Chrom(III)-Ion |
Cr(OH)2+ |
9.6 |
Dihydroxo-Chrom(III)-Ion |
Cr(OH)2+ |
5.7 |
Chrom(III)hydroxid |
Cr(OH)3 |
8.3 |
Chrom(III)hydroxid |
Cr(OH)3 |
9.1 |
Tetrahydroxo-Chromat(III)-Ion |
Cr(OH)4- |
4.9 |
|
Chromsäure |
H2CrO4 |
-0.61 |
Hydrogenchromat-Ion |
HCrO4- |
14.61 |
Hydrogenchromat-Ion |
HCrO4- |
6.45 |
Chromat-Ion |
CrO42- |
7.55 |
|
Dichromsäure |
H2Cr2O7 |
-4.5 |
Hydrogendichromat-Ion |
HCr2O7- |
18.5 |
Hydrogendichromat-Ion |
HCr2O7- |
0.07 |
Dichromat-Ion |
Cr2O72- |
13.93 |
|
Perchrom(VI)säure |
H2CrO5 |
4.95 |
Hydrogenperchromat(VI)-Ion |
HCrO5- |
9.05 |
|