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Rubidium Chloride
Rubidium chloride is the chemical compound with the formula RbCl. This alkali metal halide salt is composed of rubidium and chlorine, and finds diverse uses ranging from electrochemistry to molecular biology. Structure In its gas phase, RbCl is diatomic with a bond length estimated at 2.7868 Å. This distance increases to 3.285 Å for cubic RbCl, reflecting the higher coordination number of the ions in the solid phase. Depending on conditions, solid RbCl exists in one of three arrangements or polymorphism (materials science), polymorphs as determined with holographic imaging: Sodium chloride (octahedral 6:6) The sodium chloride (NaCl) polymorph is most common. A cubic crystal system, cubic close-packed arrangement of chloride anions with rubidium cations filling the octahedral holes describes this polymorph. Both ions are six-coordinate in this arrangement. The lattice energy of this polymorph is only 3.2 kJ/mol less than the following structure's. Caesium chlorid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g. changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment. ''Deliquescent'' materials are sufficiently hygroscopic that they dissolve in the water they absorb, forming an aqueous solution. Hygroscopy is essential for many plant and animal species' attainment of hydration, nutrition, reproduction and/or seed dispersal. Biological evolution created hygroscopic solutions for water harvesting, filament tensile strength, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Chloride
Sodium chloride , commonly known as Salt#Edible salt, edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, it is commonly used as a condiment and curing (food preservation), food preservative. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and chlorine compounds used as feedstocks for further Chemical synthesis, chemical syntheses. Another major application of sodium chloride is deicing of roadways in sub-freezing weather. Uses In addition to the many familiar domestic uses of salt, more dominant applications of the approximately 250 million tonnes per year production (2008 data) include chemicals and de-icing.Westphal, Gisbert ''et al.'' (2002) "Sodium Chloride" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim . Chem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octane Number
An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without causing engine knocking. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates the resistance to detonating under pressure without a spark. Whether a higher octane fuel improves or impairs an engine's performance depends on the design of the engine. In broad terms, fuels with a higher octane rating are used in higher-compression gasoline engines, which may yield higher power for these engines. The added power in such cases comes from the way the engine is designed to compress the air/fuel mixture, and not directly from the rating of the gasoline. In contrast, fuels with lower octane (but higher cetane numbers) are ideal for diesel engines because diesel engines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubidium-87
Rubidium (37Rb) has 36 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb (72.2%) and the radioactive 87Rb (27.8%). 87Rb has a half-life of . It readily substitutes for potassium in minerals, and is therefore fairly widespread. 87Rb has been used extensively in dating rocks; 87Rb decays to stable strontium-87 by emission of a beta particle (an electron ejected from the nucleus). During fractional crystallization, Sr tends to become concentrated in plagioclase, leaving Rb in the liquid phase. Hence, the Rb/Sr ratio in residual magma may increase over time, resulting in rocks with increasing Rb/Sr ratios with increasing differentiation. The highest ratios (10 or higher) occur in pegmatites. If the initial amount of Sr is known or can be extrapolated, the age can be determined by measurement of the Rb and Sr concentrations and the 87Sr/86Sr ratio. The dates indicate the true age of the minerals only if the rocks have not been subsequently alte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banana Equivalent Dose
Banana equivalent dose (BED) is an informal unit of measurement of ionizing radiation exposure, intended as a general educational example to compare a dose of radioactivity to the dose one is exposed to by eating one average-sized banana. Bananas contain naturally occurring radioactive isotopes, particularly potassium-40 (40K), one of several naturally occurring isotopes of potassium. One BED is often correlated to 10 sievert (0.1 μSv); however, in practice, this dose is not cumulative, as the potassium in foods is excreted in urine to maintain homeostasis. The BED is only meant as an educational exercise and is not a formally adopted dose measurement. History The origins of the concept are uncertain, but one early mention can be found on the RadSafe nuclear safety mailing list in 1995, where Gary Mansfield of the Lawrence Livermore National Laboratory mentions that he has found the "banana equivalent dose" to be "very useful in attempting to explain infinitesimal doses (and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubidium Hydrogen Sulfate
Rubidium hydrogen sulfate, sometimes referred to as rubidium bisulfate, is the half neutralized rubidium salt of sulfuric acid. It has the formula RbHSO4. Synthesis It may be synthesised with water and a stoichiometric amount of rubidium disulfate. Reaction takes place where there is no humidity:S. B. Rasmussen, H. Hamma, K. M. Eriksen, G. Hatem, M. Gaune-Escard, R. Fehrmann: "Physico-chemical properties and transition metal complex formation in alkali pyrosulfate and hydrogen sulfate melts". VII International Conference on Molten Slags Fluxes and Salts, The South African Institute of Mining and Metallurgy, 2004Volltext(PDF; 661 kB) : There is another method of creation. It is similar to the synthesis of sodium sulfate and potassium sulfate. This reaction requires rubidium chloride and a little bit of warm sulfuric acid. Some hydrogen chloride is also produced during the reaction. : Properties It is a hygroscopic compound. It has a monoclinic crystal structure, its struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desiccator
Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity. The contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires some time to achieve a low humidity. Hence they are not appropriate for storing chemicals which react quickly or violently with atmospheric moisture such as the alkali metals; a glovebox or Schlenk-type apparatus may be more suitable for these purposes. Desiccators are sometimes used to remove traces of water from an almost-dry sample. Where a desiccator alone is unsatisfactory, the sample may be dried at elevated temperature using Abderhalden's drying pistol. Constituents The lower compartment of the desiccator contains lumps of silica gel, freshly calcined quicklime, Drierite, molecular s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (chemistry)
Recrystallization is a broad class of List of purification methods in chemistry , chemical purification techniques characterized by the dissolution of an impure sample in a solvent or solvent mixture, followed by some change in conditions that encourages the formation of pure isolate as solid crystals. Recrystallization as a purification technique is driven by spontaneous process , spontaneous processes of molecular self-assembly , self-assembly that leverage the highly ordered (i.e. low-entropy) and periodic characteristics of a crystal's molecular structure to produce purification. Basic principles The driving force of this purification emerges from the difference in molecular interactions between the isolate and the impurities: if a molecule of the desired isolate interacts with any isolate crystal present, it is likely the molecule Deposition (chemistry) , deposits on the crystal's ordered surface and contributes to the crystal's growth; if a molecule of the impurity inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrochloric Acid
Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. 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. Etymology Because it was produced from halite, rock salt according to the methods of Johann Rudolph Glauber, hydrochloric acid was historically called by European alchemists ''spirits of salt'' or ''acidum salis'' (salt acid). Both names are still used, especially in other languages, such as , , , , , , , , , , (''ensan''), zh, 盐酸 (''yánsuān''), and (''yeomsan''). Gaseous HCl was called ''marine acid air''. The name ''muriatic acid'' has the same origin (''muriatic'' means "pertaining to brine or salt", hence ''muriate'' means hydrochloride), and this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO• is the hydroxyl radical. The corresponding covalently bound group of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry. Many inorganic substances which bear the word ''hydroxide'' in their names are not ionic compounds of the hydroxide ion, but covalent compounds which contain hydroxy groups. Hydroxide ion The hydroxide ion is naturally produced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lattice Energy
In chemistry, the lattice energy is the energy change (released) upon formation of one mole of a crystalline compound from its infinitely separated constituents, which are assumed to initially be in the gaseous state at 0 K. It is a measure of the cohesive forces that bind crystalline solids. The size of the lattice energy is connected to many other physical properties including solubility, hardness, and volatility. Since it generally cannot be measured directly, the lattice energy is usually deduced from experimental data via the Born–Haber cycle. Lattice energy and lattice enthalpy The concept of lattice energy was originally applied to the formation of compounds with structures like rocksalt ( NaCl) and sphalerite ( ZnS) where the ions occupy high-symmetry crystal lattice sites. In the case of NaCl, lattice energy is the energy change of the reaction: Na^+ (g) + Cl^- (g) -> NaCl (s) which amounts to −786 kJ/mol.David Arthur Johnson, ''Metals and Chemical Change' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caesium Chloride
Caesium chloride or cesium chloride is the inorganic compound with the formula Caesium, CsChloride, Cl. This colorless salt is an important source of caesium ions in a variety of niche applications. Its crystal structure forms a major structural type where each caesium ion is coordinated by 8 chloride ions. Caesium chloride dissolves in water. CsCl changes to NaCl structure on heating. Caesium chloride occurs naturally as impurities in carnallite (up to 0.002%), sylvite and kainite. Less than 20 tonnes of CsCl is produced annually worldwide, mostly from a caesium-bearing mineral pollucite. Caesium chloride is widely used in isopycnic centrifugation for separating various types of DNA. It is a reagent in analytical chemistry, where it is used to identify ions by the color and morphology of the precipitate. When enriched in radionuclide, radioisotopes, such as 137CsCl or 131CsCl, caesium chloride is used in nuclear medicine applications such as treatment of cancer and diagnosis of m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
