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Mercury(II) Thiocyanate
Mercury(II) thiocyanate (Hg(SCN)2) is an inorganic chemical compound, the coordination complex of Hg2+ and the thiocyanate anion. It is a white powder. It will produce a large, winding "snake" when ignited, an effect known as the Pharaoh's serpent. Synthesis and structure The first synthesis of mercury thiocyanate was probably completed in 1821 by Jöns Jacob Berzelius: :HgO + 2 HSCN → Hg(SCN)2 + H2O Evidence for the first pure sample was presented in 1866 prepared by a chemist named Otto Hermes. It is prepared by treating solutions containing mercury(II) and thiocyanate ions. The low solubility product of mercury thiocyanate causes it to precipitate from the solution. Most syntheses are achieved by precipitation: :Hg(NO3)2 + 2 KSCN → Hg(SCN)2 + 2KNO3 The compound adopts a polymeric structure with Hg2+ centres linearly coordinated to two S atoms with a distance of 2.381 Å. Four weak Hg2+--N interactions are indicated with distances of 2.81 Å. Uses Mercury thiocyanate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoclinic
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a parallelogram prism. Hence two pairs of vectors are perpendicular (meet at right angles), while the third pair makes an angle other than 90°. Bravais lattices Two monoclinic Bravais lattices exist: the primitive monoclinic and the base-centered monoclinic. For the base-centered monoclinic lattice, the primitive cell has the shape of an oblique rhombic prism;See , row mC, column Primitive, where the cell parameters are given as a1 = a2, α = β it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. Note that the length a of the primitive cell below equals \frac \sqrt of the conventional cell above. Crystal classes The table below org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jöns Jacob Berzelius
Baron Jöns Jacob Berzelius (; by himself and his contemporaries named only Jacob Berzelius, 20 August 1779 – 7 August 1848) was a Swedish chemist. Berzelius is considered, along with Robert Boyle, John Dalton, and Antoine Lavoisier, to be one of the founders of modern chemistry. Berzelius became a member of the Royal Swedish Academy of Sciences in 1808 and served from 1818 as its principal functionary. He is known in Sweden as the "Father of Swedish Chemistry". Berzelius Day is celebrated on 20 August in honour of him. Although Berzelius began his career as a physician, his enduring contributions were in the fields of electrochemistry, chemical bonding and stoichiometry. In particular, he is noted for his determination of atomic weights and his experiments that led to a more complete understanding of the principles of stoichiometry, which is the branch of chemistry pertaining to the quantitative relationships between elements in chemical compounds and chemical reactions and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YouTube
YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the List of most visited websites, second most visited website, after Google Search. YouTube has more than 2.5 billion monthly users who collectively watch more than one billion hours of videos each day. , videos were being uploaded at a rate of more than 500 hours of content per minute. In October 2006, YouTube was bought by Google for $1.65 billion. Google's ownership of YouTube expanded the site's business model, expanding from generating revenue from advertisements alone, to offering paid content such as movies and exclusive content produced by YouTube. It also offers YouTube Premium, a paid subscription option for watching content without ads. YouTube also approved creators to participate in Google's Google AdSens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Nitride
In organic chemistry, carbon nitrides are compounds consisting only of carbon and nitrogen atoms. Covalent network compounds * Beta carbon nitride - a solid with a formula β-, which is predicted to be harder than diamond. * Graphitic carbon nitride - g-, with important catalytic and sensor properties. Azafullerenes * Azafullerenes are a class of heterofullerenes in which the element substituting for carbon is nitrogen. Examples include (biazafullerenyl),Hummelen et al, Isolation of the Heterofullerene C59N as Its Dimer (C59N)2, Science 269: 1554-1556 (1995) (diaza 0ullerene), (triaza 0ullerene) and . Cyanofullerenes * Cyanofullerenes are a class of modified fullerenes in which cyano- groups are attached to a fullerene skeleton. These have the formula , where ''n'' takes the values 1 to 9. Cyanogen * Cyanogen - (NCCN) * Isocyanogen - (CNCN) * Diisocyanogen - (CNNC) * Paracyanogen - a cyanogen polymer, * Paraisocyanogen - a cyanogen polymer, Percyanoal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exothermic Reaction
In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change Δ''H''⚬ is negative." Exothermic reactions usually release heat. The term is often confused with exergonic reaction, which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change Δ''G''⚬ is negative." A strongly exothermic reaction will usually also be exergonic because Δ''H''⚬ makes a major contribution to Δ''G''⚬. Most of the spectacular chemical reactions that are demonstrated in classrooms are exothermic and exergonic. The opposite is an endothermic reaction, which usually takes up heat and is driven by an entropy increase in the system. Examples Examples are numerous: combustion, the thermite reaction, combining strong acids and bases, polymerizations. As an example in everyday life, hand warmers make use of the oxidation of iron to achieve an exothermic reaction: :4Fe + 3O2 → 2Fe2O3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weze Faraona
WEZE (590 AM) – branded 590 AM The Word – is a commercial Christian radio station licensed to Boston, Massachusetts, serving Greater Boston and much of surrounding New England. Owned by Salem Communications, WEZE is the Boston affiliate for the Salem Radio Network. The WEZE studios are located in the Boston suburb of North Quincy, and the station transmitter resides in neighboring Medford. Besides a standard analog transmission, WEZE is available online. History WEEI (1927-1994) Early years The Edison Electric Illuminating Company built and signed on this station as the first incarnation of WEEI, from which the call sign was derived. The electric company established WEEI as a public relations vehicle and extensively promoted the new venture weeks before launching, highlighting the usage of the latest and most advanced radio equipment. A ''Boston Globe'' profile specifically cited AT&T's success with WEAF as Edison Light's inspiration for WEEI; while the company str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reagent
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a substance ''consumed'' in the course of a chemical reaction. ''Solvents'', though involved in the reaction mechanism, are usually not called reactants. Similarly, ''catalysts'' are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates. Definitions Organic chemistry In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents. Analytical chemistry In analytical chemistry, a reagent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarrytown, NY
Tarrytown is a administrative divisions of New York#Village, village in the administrative divisions of New York#Town, town of Greenburgh, New York, Greenburgh in Westchester County, New York. It is located on the eastern bank of the Hudson River, approximately north of Midtown Manhattan in New York City, and is served by a Tarrytown station, stop on the Metro-North Railroad, Metro-North Hudson Line (Metro-North), Hudson Line. To the north of Tarrytown is the village of Sleepy Hollow, New York, Sleepy Hollow (formerly "North Tarrytown"), to the south the village of Irvington, New York, Irvington and to the east unincorporated parts of Greenburgh. The Tappan Zee Bridge (2017–present), Tappan Zee Bridge crosses the Hudson River, Hudson at Tarrytown, carrying the New York State Thruway (Interstates Interstate 87 (New York), 87 and Interstate 287, 287) to South Nyack, New York, South Nyack, Rockland County, New York, Rockland County and points in Upstate New York. The population wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solubility Product
Solubility equilibrium is a type of dynamic equilibrium that exists when a chemical compound in the solid state is in chemical equilibrium with a solution of that compound. The solid may dissolve unchanged, with dissociation, or with chemical reaction with another constituent of the solution, such as acid or alkali. Each solubility equilibrium is characterized by a temperature-dependent ''solubility product'' which functions like an equilibrium constant. Solubility equilibria are important in pharmaceutical, environmental and many other scenarios. Definitions A solubility equilibrium exists when a chemical compound in the solid state is in chemical equilibrium with a solution containing the compound. This type of equilibrium is an example of dynamic equilibrium in that some individual molecules migrate between the solid and solution phases such that the rates of dissolution and precipitation are equal to one another. When equilibrium is established and the solid has not all dissolv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pharaoh's Serpent
"Black snake" is a term that can refer to two similar types of Fireworks, firework, the Pharaoh's snake and the sugar snake. The "Pharaoh's snake" or "Pharaoh's serpent" is the original version of the black snake experiment. It produces a more impressive snake, but its execution depends upon Mercury(II) thiocyanate, mercury (II) thiocyanate, which is no longer in common use due to its toxicity. For a "sugar snake", sodium bicarbonate and sugar are the commonly used chemicals. Once lit, both fireworks emit smoke and spew out ash resembling a snake via an intumescent reaction. They remain on the ground and emit no sparks, flares, projectiles, or sound. Pharaoh's snake The Pharaoh's snake is a more dramatic experiment, yet it requires more safety precautions than the sugar snake due to the presence of toxic Mercury (element), mercury vapor and other mercury compounds. History This reaction was discovered by Friedrich Wöhler, Wöhler in 1821, soon after the first synthesis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrochloric Acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H+, and an anion, A-. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solutions .... It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical. History In the early tenth century, the Persian physician and alchemist Abu Bakr al-Razi ( 865–925, Latin: Rhazes) conducted experiments with sal ammoniac (ammonium chloride) and vitriol (hydrated sulfates of various metals), which he distilled together, thus producing the gas hydrogen chloride. In doing so, al-Razi may have stumbled upon a primitive method ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
