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Aqua Regia
Aqua regia (; from Latin, "regal water" or "royal water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar concentration, 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 alchemy, alchemists because it can dissolve noble metals such as gold and platinum, though not all metals. Preparation and decomposition Upon mixing of concentrated hydrochloric acid and concentrated nitric acid, chemical reactions occur. These reactions result in the volatile products nitrosyl chloride and chlorine gas: : as evidenced by the fuming nature and characteristic yellow color of aqua regia. As the volatile products escape from solution, aqua regia loses its potency. Nitrosyl chloride (NOCl) can further decompose into nitric oxide (NO) and elemental chlorine (): : This dissociation is equilibrium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other chemical compound, compounds. Oxygen is abundance of elements in Earth's crust, the most abundant element in Earth's crust, making up almost half of the Earth's crust in the form of various oxides such as water, carbon dioxide, iron oxides and silicates.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. It is abundance of chemical elements, the third-most abundant element in the universe after hydrogen and helium. At standard temperature and pressure, two oxygen atoms will chemical bond, bind covalent bond, covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Industrial Hygiene Association
The American Industrial Hygiene Association (AIHA) is a 501(c)6 non-profit organization, whose mission is "Creating knowledge to protect worker health." The American Industrial Hygiene Association works to provide information and resources to Industrial Hygienists and Occupational Health professionals. About The American Industrial Hygiene Association (AIHA) is an official participant of the OSHA Alliance Program. Through the AIHA-OSHA Alliance, AIHA helps OSHA provide AIHA members and the general public information on OSHA's rule making and employer compliance laws, in order to fulfill the mutual mission of ensuring safe and healthy conditions for workers. The actionable plan is twofold: 1). raise awareness, and 2). be a source of outreach and communication. AIHA worked with OSHA to provide resources available to employers and employees regarding specific hazards pertaining to relevant industries, in order to create awareness with workers and employers. AIHA has provided severa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromium Toxicity
Chromium toxicity refers to any poisonous toxic effect in an organism or cell that results from exposure to specific forms of chromium—especially hexavalent chromium. Hexavalent chromium and its compounds are toxic when inhaled or ingested. Trivalent chromium is a trace mineral that is essential to human nutrition. There is a hypothetical risk of genotoxicity in humans if large amounts of trivalent chromium were somehow able to enter living cells, but normal metabolism and cell function prevent this. Forms of chromium Hexavalent chromium and trivalent chromium are chromium ions—they have different numbers of electrons and, therefore, different properties. Trivalent chromium, or chromium(III), is the form of chromium that is essential to human health. Hexavalent chromium, or chromium(VI), is an unequivocally toxic form. Hexavalent chromium Hexavalent chromium, also called chromium(VI), is hemotoxic, genotoxic, and carcinogenic. When hexavalent chromium enters the bloo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hebrew University
The Hebrew University of Jerusalem (HUJI; ) is an Israeli public research university based in Jerusalem. Co-founded by Albert Einstein and Chaim Weizmann in July 1918, the public university officially opened on 1 April 1925. It is the second-oldest Israeli university, having been founded 30 years before the establishment of the State of Israel but six years after the older Technion university. The HUJI has three campuses in Jerusalem: one in Rehovot, one in Rishon LeZion and one in Eilat. Until 2023, the world's largest library for Jewish studies—the National Library of Israel—was located on its Edmond J. Safra campus in the Givat Ram neighbourhood of Jerusalem. The university has five affiliated teaching hospitals (including the Hadassah Medical Center), seven faculties, more than 100 research centers, and 315 academic departments. , one-third of all the doctoral candidates in Israel were studying at the HUJI. Among its first board of governors were Sigmund Freud and M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromium
Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium is valued for its high corrosion resistance and hardness. A major development in steel production was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating (electroplating with chromium) together comprise 85% of the commercial use. Chromium is also greatly valued as a metal that is able to be highly polishing, polished while resisting tarnishing. Polished chromium reflects almost 70% of the visible spectrum, and almost 90% of infrared, infrared light. The name of the element is derived from the Ancient Greek, Greek word χρῶμα, ''chrōma'', meaning color, because many chromium compounds are intensely colored. Indust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NMR Tube
An NMR tube is a thin glass walled tube used to contain samples in nuclear magnetic resonance spectroscopy. Typically NMR tubes come in 5 mm diameters but 10 mm and 3 mm samples are known. It is important that the tubes are uniformly thick and well-balanced to ensure that NMR tube spins at a regular rate (i.e., they do not wobble), usually about 20 Hz in the NMR spectrometer. Construction NMR tubes are typically made of borosilicate glass. They are available in seven and eight inch lengths; a 5 mm tube outer diameter is most common, but 3 mm and 10 mm outer diameters are available as well. Where boron NMR is desired, quartz NMR tubes containing low concentrations of boron (as opposed to borosilicate glass) are available. Specialized closures such as J. Young valves and screwcap closures are available aside from more common polyethylene caps. Two common specifications for NMR tubes are concentricity and camber. Concentricity refers to the variati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromic Acid
Chromic acid is a chemical compound with the chemical formula . It is also a jargon for a solution formed by the addition of sulfuric acid to aqueous solutions of dichromate. It consists at least in part of chromium trioxide. The term "chromic acid" is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the molecular species, of which the trioxide is the anhydride. Chromic acid features chromium in an oxidation state of +6 (and a valence of VI or 6). It is a strong and corrosive oxidizing agent and a moderate carcinogen. Molecular chromic acid Molecular chromic acid, , in principle, resembles sulfuric acid, . It would ionize accordingly: : The p''K''a for the equilibrium is not well characterized. Reported values vary between about −0.8 to 1.6. The structur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion , hydrogen cyanide , chloroformic acid , carbon dioxide , and carbonate ion ). Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Glassware
Laboratory glassware is a variety of equipment used in science, scientific work, traditionally made of glass. Glass may be blown, bent, cut, molded, or formed into many sizes and shapes. It is commonly used in chemistry, biology, and analytical laboratory, laboratories. Many laboratories have training programs to demonstrate how glassware is used and to alert first–time users to the Laboratory safety#Safety hazards, safety hazards involved with using glassware. History Ancient era The history of glassware dates back to the Phoenicians who fused obsidian together in campfires, making the first glassware. Glassware evolved as other ancient civilizations including the Syrians, Egyptians, and Romans refined the art of glassmaking. Mary the Jewess, an alchemist in Alexandria during the 1st century AD, is credited for the creation of some of the first glassware for chemical such as the ''kerotakis'' which was used for the collection of fumes from a heated material. Despite thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Chemistry
Analytical skill, Analytical chemistry studies and uses instruments and methods to Separation process, separate, identify, and Quantification (science), quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative inorganic analysis, Qualitative analysis identifies analytes, while Quantitative analysis (chemistry), quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemistry, wet chemical methods and modern analytical techniques. Classical qualitative methods use separations such as Precipitation (chemistry), precipitation, Extraction (chemistry), extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, solubility, radioactivity or reactivity. Classical quantitative analysis uses mass or volume changes to quantify amount. Ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Milling
Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. Other names for chemical etching include photo etching, chemical etching, photo chemical etching and photochemical machining. It is mostly used on metals, though other materials are increasingly important. It was developed from armor-decorating and printing etching processes developed during the Renaissance as alternatives to engraving on metal. The process essentially involves bathing the cutting areas in a corrosive chemical known as an etchant, which reacts with the material in the area to be cut and causes the solid material to be dissolved; inert substances known as maskants are used to protect specific areas of the material as resists. History Organic chemicals such as lactic acid and citric acid have been used to etch metals and create products as early as 400 BCE, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
