臭化カルシウム

解説炭酸カルシウムを臭化水素酸に溶かし，濃縮すると六水和物が得られる．水素と臭化水素の気流中で熱して脱水すると無水物となるカルシウムと臭素の化合物。炭酸カルシウムを臭化水素酸に溶解し、蒸発濃縮すると六水和物（無色の六方晶系。式量308.0、融点38.2℃、沸点149℃）として得られる。これを水素と臭化水素の混合気流中で脱水して無水和物とする。無色の結晶性固体。潮解性で、水に溶けやすい。エタノール（エチルアルコール）、アセトンにも可溶。写真用定着剤、医薬（中枢神経抑制剤、鎮静剤、鎮けい剤）として用いる。［鳥居泰男］[補完資料] | 臭化カルシウム（データノート）小学館 日本大百科全書(ニッポニカ) ）

用途写真用感光剤，医薬品

説明Calcium bromide has the chemical formula CaBr2. It was first prepared by Pfeiffer, Klossmann and Angern in 1924. It is a deliquescent salt that has the form of colorless hexagonal crystals that are soluble in water and absolute alcohol. Its molecular weight is 199.90 g/ mol for the anhydride. When strongly heated in air, calcium bromide will produce CaO (lime) and Br2. It is generally obtained as the dihydrate, CaBr2·2H2O, in the form of a white crystalline powder. A hexahydrate, CaBr2·6H2O, is also known. Anhydrous calcium bromide is obtained by dehydration (250°C, vacuum) of the dihydrate CaBr2·2H2O. On contact with hot surfaces or flames, CaBr2 decomposes forming bromine as a toxic and corrosive fume. It also reacts with strong acids to produce corrosive fumes of bromine. In its solid anhydrous state, it is a white powder. CaBr2 can be found in drilling muds, neuroses medication, freezing mixtures, food preservatives, photography and fire retardants. The anhydride has a melting point of 730°C and a boiling point of 810°C where it decomposes. Its density is 3.41 g/cm3. It is moderately soluble in water at 142 g/100 ml of water.

使用Made by the action of hydrobromic acid on calcium oxide and crystallization. The white granular crystals are soluble in water. Calcium bromide was used in making collodion emulsions, particularly for dye-sensitized plates.

製造方法CaBr2·2H2O has a melting point of 38°C where it dissolves in its own waters of hydration. Its density is 2.290 g/cm3. It can be prepared by reaction in solution with HBr on the carbonate: CaCO3 (solid)＋HBr (liq)→CaBr2 (liq)＋ CO2 (gas) An improved method for producing calcium bromide has been developed by reacting hydrogen bromide with calcium hydroxide in the presence of water.

合成方法炭酸カルシウムを臭化水素酸に溶解し，濃縮した六水和物を臭化水素雰囲気で加熱脱水する