Cobalt Hydroxide - Suisanka Cobalt

[ I ] Cobalt(II) hydroxide: Co(OH) ₂ (92.95). A pink powder. It is obtained by adding sodium hydroxide to an aqueous solution of cobalt(II) salt. At first, it is a fine blue precipitate, but if left to stand, the particles will grow larger and turn pink. Density: 3.60 g cm ^-3 . It is an amphoteric compound that dissolves in acid to become cobalt(II) salt, and when heated in an alkali, it produces tetrahydroxocobalt(II) salt M ^Ⅰ ₂ [Co(OH) ₄ ], which turns into a blue solution. It is easily oxidized. In air, it gradually absorbs oxygen and turns into brown cobalt(III) hydroxide. It is sparingly soluble in water, but soluble in ammonia water and ammonium salt aqueous solution. It is used in the production of metallic cobalt, as a positive electrode material for nickel-hydrogen batteries, metal soap, catalysts, etc. [CAS 21041-93-0] [ II ] Cobalt(III) hydroxide: Co(OH) ₃ (109.96). Also known as hydrated cobalt(III) oxide. In practice, the formula is Co ₂ O ₃ ･ n H ₂ O, where n = 3. Dark brown powder. It is obtained by adding sodium hydroxide to an aqueous solution of cobalt(III) salt. Density: 4.46 g cm ^-3. It loses water at 100 °C. It dissolves in hydrochloric acid to produce chlorine. It is sparingly soluble in nitric acid and sulfuric acid, and insoluble in water, ethanol, and aqueous ammonia. [CAS 1307-86-4]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

【Ⅰ】水酸化コバルト(Ⅱ)：Co(OH)₂(92.95)．ばら色の粉末．コバルト(Ⅱ)塩水溶液に水酸化ナトリウムを加えると得られるが，最初は青色の微細沈殿で，放置すると粒子が大きくなりばら色にかわる．密度3.60 g cm^－3．両性化合物で，酸に溶けてコバルト(Ⅱ)塩になり，アルカリには加熱するとテトラヒドロキソコバルト(Ⅱ)酸塩M^Ⅰ₂[Co(OH)₄]を生じ，青色溶液になる．酸化されやすい．空気中では徐々に酸素を吸収して褐色の水酸化コバルト(Ⅲ)になる．水に難溶，アンモニア水，アンモニウム塩水溶液に可溶．金属コバルトの製造，ニッケル水素電池の正極材料，金属せっけん，触媒などに用いられる．[CAS 21041-93-0]【Ⅱ】水酸化コバルト(Ⅲ)：Co(OH)₃(109.96)．水和酸化コバルト(Ⅲ)ともいう．実際にはCo₂O₃･nH₂Oでn ＝ 3が普通である．暗褐色の粉末．コバルト(Ⅲ)塩水溶液に水酸化ナトリウムを加えると得られる．密度4.46 g cm^－3．100 ℃ で水を失う．塩酸に溶けて塩素を発生する．硝酸，硫酸に難溶，水，エタノール，アンモニア水に不溶．[CAS 1307-86-4]

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