水酸化バリウム

解説水酸化バリウム，無水和物は白色の無定形の粉末で，比重4.49，融点325℃(水素気流中)。融解物を冷却すると，単斜晶系の結晶にもなる。他のアルカリ土類金属の水酸化物よりも水に溶けやすく，BaOとしての溶解度は3.84g/100g(20℃)。

用途二酸化炭素や炭酸塩と反応して炭酸バリウムの沈殿を生じるのでこれらの定量に用いられる．せっけん(脂肪のけん化剤)，触媒，潤滑油，耐熱グリース，樹脂安定剤，ガラスの製造，精糖，硫酸イオンの除去剤，ケイ酸塩の融解などに用いられる．

説明Barium Hydroxide occurs as an anhydrate whose prismatic, colorless crystals are very deliquescent. Barium hydroxide can be prepared by dissolving barium oxide (BaO) in water: BaO＋ 9H2O→Ba(OH)2·8H2O It crystallizes as the octahydrate, which converts to the monohydrate upon heating in air. Barium oxide has been found to react with water vapor at temperatures from 1443 to 1593 K to form gaseous Ba(OH)2 according to the reaction: BaO(solid)＋H2O(gas)→Ba(OH)2(gas) A better method of preparation involves addition of NaOH to the nitrate. Since barium hydroxide is fairly soluble, it is necessary to evaporate the solution to crystallize Ba(OH)2·8H2O. Ethanol is added to aid in this crystallization. The crystals are washed in cold ethanol to remove sodium ions and then dried.

使用Barium hydroxide is used in analytical chemistry to titrate weak acids, particularly organic acids. It forms clear aqueous solutions that are free from carbonate, unlike those of the alkali hydroxides, since barium carbonate is insoluble in water. This allows the use of indicators such as phenolphthalein or thymophthalein (with alkaline color changes) without the risk of titration errors due to the presence of weakly basic CO32- ions.Barium hydroxide is used in organic synthesis as a strong base, for example for the hydrolysis of esters and nitriles.It has been used to hydrolyze one of the two equivalent ester groups in dimethyl endecanedioate. It is also used in the preparation of cyclopentanone, diacetone alcohol and d-Gluonic g-lactone. Barium hydroxide is used as an additive in thermoplastics (such as phenolic resins), rayon and PVC stabilizers to improve plastic properties. This material is used as a general-purpose additive for lubricants and greases. Other industrial applications for barium hydroxide include sugar fabrication, manufacturing soaps, fat saponification, fusing of silicates and chemical synthesis of other barium compounds and organic compounds. Barium hydroxide is offered for sale both as the octahydrate and the monohydrate. It is available in large quantities commercially.

使用用途水酸化バリウムは、の製造や油の精製、水の軟化、製糖、各種バリウム化合物の製造、有機合成など、幅広い用途で用いられています。また、やの安定剤として利用されるバリウム石鹸の製造において、油脂の鹸化にも使用可能です。 水酸化バリウムは、中和滴定のアルカリ標準液や二酸化炭素の定量など、分析試薬・実験試薬としても利用されています。水酸化バリウムは他にも、触媒や潤滑油添加剤の製造、顔料の原料、の中和除去剤、めっき用試薬、ケイ酸塩の融解などにも使用されています。