| Identification | More | [Name]
Cobalt hydroxide | [CAS]
21041-93-0 | [Synonyms]
COBALT HYDROXIDE
COBALT HYDROXIDE BLACK
COBALT(II) HYDROXIDE
cobalt(2+)hydroxide
cobaltdihydroxide
cobalthydroxide(co(oh)2)
cobaltoushydroxide
COBALT HYDROXID
COBALT HYDROXIDE 61 % MIN
COBALT(II) HYDROXIDE, TECH., 95%
Cobalt(II)hydroxide(97%-Co)
Cobalt hydroxide
Cobalt(II) hydroxide, 99.9% (metals basis)
Cobalt (II) hydroxide, 61/62%,
Cobalt(II)dihydoxide | [EINECS(EC#)]
244-166-4 | [Molecular Formula]
CoH2O2 | [MDL Number]
MFCD00016015 | [Molecular Weight]
92.95 | [MOL File]
21041-93-0.mol |
| Chemical Properties | Back Directory | [Appearance]
Rose-red powder.Soluble in
acids and ammonium salt solutions; insoluble in
water and alkalies. | [Melting point ]
°Cd ec.) | [density ]
3.597 g/mL at 25 °C(lit.)
| [vapor pressure ]
0Pa@20°C | [storage temp. ]
Inert atmosphere,Room Temperature | [solubility ]
Soluble in acids and ammonia. Very slightly soluble in water. Insoluble in dilute alkalis. | [form ]
Powder | [color ]
Pink to purple | [Specific Gravity]
3.597 | [PH]
9.15(1 mM solution);9.15(10 mM solution);9.15(100 mM solution) | [Stability:]
Stability | [Water Solubility ]
Soluble in acids and ammonia. Very slightly soluble in water. Insoluble in dilute alkalis. | [Sensitive ]
Air Sensitive | [Merck ]
14,2442 | [Solubility Product Constant (Ksp)]
pKsp: 14.23 | [Exposure limits]
ACGIH: TWA 0.02 mg/m3 | [Uses]
Cobalt salts, paint and varnish driers, catalyst,
storage-battery electrodes. | [CAS DataBase Reference]
21041-93-0(CAS DataBase Reference) | [EPA Substance Registry System]
21041-93-0(EPA Substance) |
| Safety Data | Back Directory | [Hazard Codes ]
Xn | [Risk Statements ]
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed .
R36/37/38:Irritating to eyes, respiratory system and skin . | [Safety Statements ]
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S37/39:Wear suitable gloves and eye/face protection . | [RIDADR ]
UN 3077 9 / PGIII | [WGK Germany ]
3
| [RTECS ]
GG0904500
| [TSCA ]
Yes |
| Questions And Answer | Back Directory | [Physical Properties]
Two forms occur, a rose-red powder (more stable) and a bluish-green powder less stable than the red form; rhombohedral crystals; density 3.597 g/cm3; decomposes on heating; practically insoluble in water 3.2 mg/L; Ksp 1.0x10–15; soluble in acids and ammonia; insoluble in dilute alkalis.
The addition of alkali metal hydroxides to solutions of cobalt(II) salts results in the precipitation of cobalt(II) hydroxide in either a blue or pink form depending upon the conditions. The pink form is the more stable of the two and is obtained when a suspension of the blue form is allowed to stand or is warmed. Cobalt(II) hydroxide is amphoteric, dissolving in alkalis to form blue solutions of the [Co(OH)4]2~ ions. In the presence of alkali, suspensions of Co(OH)8 are oxidized by air to the brown CoO(OH), this oxidation being brought about rapidly by oxidants such as hypochlorite, bromine water or hydrogen peroxide. The pink Co(OH)2 (density 3.597) has the brucite (Mg(OH)2) structure in which the cobalt atoms are surrounded by six hydroxides. The blue form is more disordered, but its structure is not known for certain. | [Uses]
Cobalt(II) hydroxide is used as a drier for paints and varnishes and is added to lithographic printing inks to enhance their drying properties. Other applications are in the preparation of cobalt salts; as a catalyst; and in storage battery electrodes.
| [Preparation]
Cobalt(II) hydroxide is obtained as a precipitate when an alkaline hydroxide is added to an aqueous solution of cobalt(II) salt:
CoCl2 + 2NaOH → Co(OH)2 + 2NaCl
Co(NO3)2 + 2NaOH → Co(OH)2 + 2NaNO3
| [Reactions]
Thermal decomposition to cobaltous oxide, CoO, occurs at 168°C in a vacuum.
Cobalt(II) hydroxide is oxidized by air and other oxidizing agents, forming cobalt(III) hydroxide, Co(OH)3. Reactions with mineral acids produce corresponding Co2+ salts.
|
| Hazard Information | Back Directory | [Description]
The addition of alkali metal hydroxides to solutions of cobalt(II) salts results in the precipitation of cobalt(II) hydroxide in either a blue or pink form depending upon the conditions. The pink form is the more stable of the two and is obtained when a suspension of the blue form is allowed to stand or is warmed. Cobalt(II) hydroxide is amphoteric, dissolving in alkalis to form blue solutions of the [Co(OH)4]2- ions. In the presence of alkali, suspensions of Co(OH) are oxidized by air to the brown CoO(OH), this oxidation being brought about rapidly by oxidants such as hypochlorite, bromine water or hydrogen peroxide. The pink Co(OH)2 (density 3.597) has the brucite (Mg(OH)2) structure in which the cobalt atoms are surrounded by six hydroxides. The blue form is more disordered, but its structure is not known for certain. | [Chemical Properties]
Rose-red powder.Soluble in
acids and ammonium salt solutions; insoluble in
water and alkalies. | [Flammability and Explosibility]
Notclassified(100%) |
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