Barium hydroxide is mixed with many solutions of other metal salts. Reactions of barium hydroxide with ammonium salts are strongly endothermic. The reaction of barium hydroxide octahydrate with ammonium chloride or ammonium thiocyanate is often used as a classroom chemistry demonstration, producing temperatures cold enough to freeze water and enough water to dissolve the resulting mixture. Barium hydroxide presents the same hazards as other strong bases and as other water-soluble barium compounds: it is corrosive and toxic. Barium hydroxide Barium hydroxide is a chemical compound with the chemical formula Ba(OH)(HO). The monohydrate (x =1), known as baryta or baryta-water, is one of
Chemical element plants, the calcium in mollusc shells, or the iron in the hemoglobin in vertebrate animals' red blood cells. The concept of an "element" as an undivisible substance has developed through three major historical phases: Classical definitions (such as those of the ancient Greeks), chemical definitions, and atomic definitions. Ancient philosophy posited a set of classical elements to explain observed patterns in nature. These "elements" originally referred to "earth", "water", "air" and "fire" rather than the chemical elements of modern science. The term 'elements' ("stoicheia") was first used by the Greek philosopher Plato in about 360 BCE in his dialogue Timaeus,