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The solid dihydrate and hexahydrate can be obtained by evaporation. Cooling saturated aqueous solutions yields the dihydrate between 120.2 °C and 51.25 °C, and the hexahydrate below 51.25 °C. Water ice, rather than cobalt chloride, will crystallize from solutions with concentration below 29%.
Cobalt can easily react with nitric acid to form cobalt(II) nitrate Co(NO 3) 2. Cobalt(II) nitrate exists in the anhydrous form and the hydrate form, of which the hexahydrate is the most common. Cobalt nitrate hexahydrate (Co(NO 3) 2 ·6H 2 O) is a red deliquescence crystal that is easily soluble in water, [12] and its molecule contains cobalt ...
A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-colored metal aquo complex [Co(H 2 O) 6] 2+ in water. Addition of chloride gives the intensely blue [CoCl 4] 2−. [7] In a borax bead flame test, cobalt shows deep blue in both oxidizing and reducing flames. [20]
CoCl 2 ·6H 2 O – cobalt(II) chloride hexahydrate SnCl 2 ·2H 2 O – tin(II) ( or stannous) chloride dihydrate For many salts, the exact bonding of the water is unimportant because the water molecules are made labile upon dissolution.
A colorful example is cobalt(II) chloride, which turns from blue to red upon hydration, and can therefore be used as a water indicator.. The notation "hydrated compound⋅n H 2 O", where n is the number of water molecules per formula unit of the salt, is commonly used to show that a salt is hydrated.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
The compound is usually prepared by mixing cobalt(II) chloride, dimethylglyoxime and pyridine in an ethanolic solution. This process afford the cobaloxime(II), which is subsequently oxidized by the oxygen in air: [3] 4 CoCl 2 •6H 2 O + 8 dmgH 2 + 8 py + O 2 → 4 ClCo(dmgH) 2 py + 4 py•HCl + 14 H 2 O
Cobalt(II) sulfate heptahydrate. Cobalt(II) sulfate is any of the inorganic compounds with the formula CoSO 4 (H 2 O) x. Usually cobalt sulfate refers to the hexa- or heptahydrates CoSO 4. 6H 2 O or CoSO 4. 7H 2 O, respectively. [1] The heptahydrate is a red solid that is soluble in water and methanol. Since cobalt(II) has an odd number of ...