Sodium chloride melting point

Probably the most amazing feature of ionic liquids is that they are liquid. Intuitively, we expect salts to be solid at room temperature and to melt only at very high temperatures. Take sodium chloride (melting point 803°C) since its ions have similar size and shape, a solid, crystalline packing structure is obtained. In contrast, the ions forming ionic liquids do not pack well, which explains why they can remain liquid at low temperature. ... 

Demonstrations of melting lead (melting point 328 °C) and sodium chloride (melting point 801 °C) can follow. (For the latter use large crystals from rock salt and three Bunsen flames.) The temperatures cannot be measured, but draw attention to the distinct change from solid to runny liquid which is characteristic of a precise melting point. 

Highway. Rock salt, solar salt, and in some cases in Europe, evaporated salt are used to maintain traffic safety and mobiUty during snow and ice conditions in snowbelt regions throughout the world. Sodium chloride melts ice at temperatures down to its eutectic point of —21.12°C. Most snowstorms occur when the temperature is near 0°C, where salt is very effective. More than 40% of dry salt produced in the United States is used for highway deicing. 

Pure sodium chloride melts at 801 °C. The addition of calcium chloride, CaCl2, to the NaCl lowers the melting point. The Downs cell can then work at 590 °C, and less energy is needed to run the cell. The equations below describe the major reactions that occur. 

A) Ionic Crystals. These are transparent, have high melting-points (e.g. sodium chloride melts at, 801° l1.), have very low electrical conductivity, and are hard, elastic under tension but brittle under impact. 

The forces holding ionic solids together are strong coulombic forces (or ionic bonds), and since these forces are much stronger than the intermolecular forces, ionic solids tend to have much higher melting points than molecular solids. For example, sodium chloride melts at 801 °C, while carbon disulfide (CS2)—a molecular solid with a higher molar mass—melts at —110 °C. 

Substances in this category include Krypton, sodium chloride, and diamond, as examples, and it is not surprising that differences in detail as to frictional behavior do occur. The softer solids tend to obey Amontons law with /i values in the normal range of 0.5-1.0, provided they are not too near their melting points. Ionic crystals, such as sodium chloride, tend to show irreversible surface damage, in the form of cracks, owing to their brittleness, but still tend to obey Amontons law. This suggests that the area of contact is mainly determined by plastic flow rather than by elastic deformation. 

Add 1 ml. of the alcohol-free ether to 0-1-0-15 g. of finely-powdered anhydrous zinc chloride and 0 5 g. of pure 3 5-dinitrobenzoyl chloride (Section 111,27,1) contained in a test-tube attach a small water condenser and reflux gently for 1 hour. Treat the reaction product with 10 ml. of 1-5N sodium carbonate solution, heat and stir the mixture for 1 minute upon a boiling water bath, allow to cool, and filter at the pump. Wash the precipitate with 5 ml. of 1 5N sodium carbonate solution and twice with 6 ml. of ether. Dry on a porous tile or upon a pad of filter paper. Transfer the crude ester to a test-tube and boil it with 10 ml. of chloroform or carbon tetrachloride filter the hot solution, if necessary. If the ester does not separate on cooling, evaporate to dryness on a water bath, and recrystallise the residue from 2-3 ml. of either of the above solvents. Determine the melting point of the resulting 3 5 dinitro benzoate (Section 111,27). 

Dissolve 5 g. of phenol in 75 ml. of 10 per cent, sodium hydroxide solution contained in a wide-mouthed reagent bottle or conical flask of about 200 ml. capacity. Add 11 g. (9 ml.) of redistilled benzoyl chloride, cork the vessel securely, and shake the mixture vigorously for 15-20 minutes. At the end of this period the reaction is usually practically complete and a sohd product is obtained. Filter oflf the soUd ester with suction, break up any lumps on the filter, wash thoroughly with water and drain well. RecrystaUise the crude ester from rectified (or methylated) spirit use a quantity of hot solvent approximately twice the minimum volume required for complete solution in order to ensure that the ester does not separate until the temperature of the solution has fallen below the melting point of phenyl benzoate. Filter the hot solution, if necessary, through a hot water funnel or through a Buchner funnel preheated by the filtration of some boiling solvent. Colourless crystals of phenyl benzoate, m.p. 69°, are thus obtained. The yield is 8 g. 

Acetaldehyde can be isolated and identified by the characteristic melting points of the crystalline compounds formed with hydrazines, semicarbazides, etc these derivatives of aldehydes can be separated by paper and column chromatography (104,113). Acetaldehyde has been separated quantitatively from other carbonyl compounds on an ion-exchange resin in the bisulfite form the aldehyde is then eluted from the column with a solution of sodium chloride (114). In larger quantities, acetaldehyde may be isolated by passing the vapor into ether, then saturating with dry ammonia acetaldehyde—ammonia crystallizes from the solution. Reactions with bisulfite, hydrazines, oximes, semicarb azides, and 5,5-dimethyl-1,3-cyclohexanedione [126-81 -8] (dimedone) have also been used to isolate acetaldehyde from various solutions. 

The first reported synthesis of acrylonitrile [107-13-1] (qv) and polyacrylonitrile [25014-41-9] (PAN) was in 1894. The polymer received Htde attention for a number of years, until shortly before World War II, because there were no known solvents and the polymer decomposes before reaching its melting point. The first breakthrough in developing solvents for PAN occurred at I. G. Farbenindustrie where fibers made from the polymer were dissolved in aqueous solutions of quaternary ammonium compounds, such as ben2ylpyridinium chloride, or of metal salts, such as lithium bromide, sodium thiocyanate, and aluminum perchlorate. Early interest in acrylonitrile polymers (qv), however, was based primarily on its use in synthetic mbber (see Elastomers, synthetic). 

Lithium Carbonate. Lithium carbonate [554-13-2], Li2C02, is produced in industrial processes from the reaction of sodium carbonate and Hthium sulfate or Hthium chloride solutions. The reaction is usually performed at higher temperatures because aqueous Hthium carbonate solubiHty decreases with increasing temperatures. The solubiHty (wt %) is 1.52% at 0°C, 1.31% at 20°C, 1.16% at 40°C, 1.00% at 60°C, 0.84% at 80°C, and 0.71% at 100°C. Lithium carbonate is the starting material for reactions to produce many other Hthium salts, including the hydroxide. Decomposition of the carbonate occurs above the 726°C melting point. 

The cell bath in early Downs cells (8,14) consisted of approximately 58 wt % calcium chloride and 42 wt % sodium chloride. This composition is a compromise between melting point and sodium content. Additional calcium chloride would further lower the melting point at the expense of depletion of sodium in the electrolysis 2one, with the resulting compHcations. With the above composition, the cells operate at 580—600°C, well below the temperature of highest sodium solubiUty in the salt bath. Calcium chloride causes problems because of the following equiUbrium reaction (56) ... 

Reaction with hydrogen at 220°C in the presence of reduced nickel catalyst results in total decomposition to hydrogen chloride and carbon. An explosive reaction occurs with butylUthium in petroleum ether solution (4). Tetrachloroethylene also reacts explosively with metallic potassium at its melting point, however it does not react with sodium (5). 

A solution of 24.6 g of o-allyl-epoxypropoxybenzene dissolved in 250 ml of absolute ethanol saturated with ammonia was placed in an autoclave and heated on a steam-bath for 2 hours. The alcohol was then removed by distillation and the residue was redissolved in a mixture of methanol and ethylacetate. Hydrogen chloride gas was introduced into the solution. The hydrochloride salt was then precipitated by the addition of ether to yield 11.4 g of product. Five grams of the amine-hydrochloride thus formed were dissolved in 50 ml of methanol and 9 ml of acetone. The resulting solution was cooled to about 0°C. At this temperature 5 g of sodium borohydride were added over a period of 1 hour. Another 2.2 ml of acetone and O.B g of sodium borohydride were added and the solution was kept at room temperature for 1 hour, after which 150 ml of water were added to the solution. The solution was then extracted with three 100-ml portions of ether which were combined, dried over potassium carbonate, and evaporated. The free base was then recrystallized from petrol ether (boiling range 40°-60°C) to yield 2.7 g of material having a melting point of 57°C. 

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