Aqua regia is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a fuming liquid. Freshly prepared aqua regia is colorless, but it turns yellow, orange or red within seconds from the formation of nitrosyl chloride and nitrogen dioxide. It was so named by alchemists because it can dissolve noble metals like gold and platinum, though not all metals.
Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula NH+4 or [NH4]+. It is formed by the addition of a proton to ammonia. Ammonium is also a general name for positively charged (protonated) substituted amines and quaternary ammonium cations, where one or more hydrogen atoms are replaced by organic or other groups. Not only is ammonium a source of nitrogen and a key metabolite for many living organisms, but it is an integral part of the global nitrogen cycle. As such, human impact in recent years could have an effect on the biological communities that depend on it.
Ammonium bicarbonate is an inorganic compound with formula (NH4)HCO3. The compound has many names, reflecting its long history. Chemically speaking, it is the bicarbonate salt of the ammonium ion. It is a colourless solid that degrades readily to carbon dioxide, water and ammonia.
Europium(III) chloride is an inorganic compound with the formula EuCl3. The anhydrous compound is a yellow solid. Being hygroscopic it rapidly absorbs water to form a white crystalline hexahydrate, EuCl3·6H2O, which is colourless. The compound is used in research.
Dysprosium(III) chloride (DyCl3), also known as dysprosium trichloride, is a compound of dysprosium and chlorine. It is a white to yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate, DyCl3·6H2O. Simple rapid heating of the hydrate causes partial hydrolysis to an oxychloride, DyOCl.
Rhodium(III) chloride refers to inorganic compounds with the formula RhCl3(H2O)n, where n varies from 0 to 3. These are diamagnetic red-brown solids. The soluble trihydrated (n = 3) salt is the usual compound of commerce. It is widely used to prepare compounds used in homogeneous catalysis.
Iridium(III) chloride is the inorganic compound with the formula IrCl3. The anhydrous compound is relatively rare, but the related hydrate is much more commonly encountered. The anhydrous salt has two polymorphs, α and β, which are brown and red colored respectively. More commonly encountered is the hygroscopic dark green trihydrate IrCl3(H2O)3 which is a common starting point for iridium chemistry.
Chromium(III) fluoride is an inorganic compound with the chemical formula CrF3. It forms several hydrates. The compound CrF3 is a green crystalline solid that is insoluble in common solvents, but the hydrates [Cr(H2O)6]F3 (violet) and [Cr(H2O)6]F3·3H2O (green) are soluble in water. The anhydrous form sublimes at 1100–1200 °C.
Yttrium(III) chloride is an inorganic compound of yttrium and chloride. It exists in two forms, the hydrate (YCl3(H2O)6) and an anhydrous form (YCl3). Both are colourless salts that are highly soluble in water and deliquescent.
Indium(III) sulfate (In2(SO4)3) is a sulfate salt of the metal indium. It is a sesquisulfate, meaning that the sulfate group occurs 11/2 times as much as the metal. It may be formed by the reaction of indium, its oxide, or its carbonate with sulfuric acid. An excess of strong acid is required, otherwise insoluble basic salts are formed. As a solid indium sulfate can be anhydrous, or take the form of a pentahydrate with five water molecules or a nonahydrate with nine molecules of water. Indium sulfate is used in the production of indium or indium containing substances. Indium sulfate also can be found in basic salts, acidic salts or double salts including indium alum.
Hexafluorophosphate is an anion with chemical formula of [PF6]−. It is an octahedral species that imparts no color to its salts. [PF6]− is isoelectronic with sulfur hexafluoride, SF6, and the hexafluorosilicate dianion, [SiF6]2−, and hexafluoroantimonate [SbF6]−. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.
Ammonium iron(III) sulfate, NH4Fe(SO4)2·12 H2O, or NH4[Fe(H2O)6](SO4)2·6 H2O, also known as ferric ammonium sulfate (FAS) or iron alum, is a double salt in the class of alums, which consists of compounds with the general formula AB(SO4)2 · 12 H2O. It has the appearance of weakly violet, octahedrical crystals. There has been some discussion regarding the origin of the crystals' color, with some ascribing it to impurities in the compound, and others claiming it to be a property of the crystal itself.
Ammonium fluorosilicate (also known as ammonium hexafluorosilicate, ammonium fluosilicate or ammonium silicofluoride) has the formula (NH4)2SiF6. It is a toxic chemical, like all salts of fluorosilicic acid. It is made of white crystals, which have at least three polymorphs and appears in nature as rare minerals cryptohalite or bararite.
Sodium hexachloroplatinate(IV), the sodium salt of chloroplatinic acid, is an inorganic compound with the formula Na2[PtCl6], consisting of the sodium cation and the hexachloroplatinate anion. As explained by Cox and Peters, anhydrous sodium hexachloroplatinate, which is yellow, tends to form the orange hexahydrate upon storage in humid air. The latter can be dehydrated upon heating at 110 °C.
Lanthanide trichlorides are a family of inorganic compound with the formula LnCl3, where Ln stands for a lanthanide metal. The trichlorides are standard reagents in applied and academic chemistry of the lanthanides. They exist as anhydrous solids and as hydrates.
Ammonium hexachlorostannate is an inorganic chemical compound with the chemical formula (NH4)2SnCl6.
Ammonium hexacyanoferrate(II) is an inorganic chemical compound with the chemical formula (NH4)4[Fe(CN)6].
Ammonium hexachloroplumbate is an inorganic chemical compound with the chemical formula (NH4)2PbCl6.
Ammonium hexachloropalladate is an inorganic chemical compound with the chemical formula (NH4)2PdCl6.
Ammonium hexachloroosmate(IV) is an inorganic chemical compound with the chemical formula (NH4)2OsCl6.
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