Anhydrous, definition

An acid was once defined simply as a substance which produces hydrogen ions, or protons. However, the simple proton, H , is never found under ordinary conditions, and this definition required amendment. Bronsted and, independently, Lowry, therefore redefined an acid as a susbstance able to donate protons to other molecules or ions, and a base as a substance capable of accepting such protons. If we consider hydrogen chloride, HCl, as an example, the HCl molecule is essentially covalent, and hydrogen chloride (gas or liquid) contains no protons. But anhydrous hydrogen chloride in benzene will react with anhydrous ammonia ... 

The precipitate obtained is in fact colloidal and has no definite composition. Careful drying of the precipitate gives the anhydrous oxide, SnO, which may also be prepared by heating tin(II) ethane-dioate (oxalate) ... 

Furthermore, it is the system. Hydrate I/Hydrate II (or Anhydrous Salt), that possesses a definite pressure at a particular temperature this is independent of the relative amounts, but is dependent upon the nature of the two components in equilibrium. It is incorrect, therefore, to speak of the vapour pressure of a salt hydrate. ... 

To the cold acid chloride add 175 ml. of pure carbon disulphide, cool in ice, add 30 g, of powdered anhydrous aluminium chloride in one lot, and immediately attach a reflux condenser. When the evolution of hydrogen chloride ceases (about 5 minutes), slowly warm the mixture to the boiling point on a water bath. Reflux for 10 minutes with frequent shaking the reaction is then complete. Cool the reaction mixture to 0°, and decompose the aluminium complex by the cautious addition, with shaking, of 100 g. of crushed ice. Then add 25 ml. of concentrated hydrochloric acid, transfer to a 2 htre round-bottomed flask and steam distil, preferably in the apparatus, depicted in Fig. II, 41, 3 since the a-tetralone is only moderately volatile in steam. The carbon disulphide passes over first, then there is a definite break in the distillation, after whieh the a-tetralone distils completely in about 2 htres of distillate. 

Super Lewis Acids. Acid systems stronger than anhydrous AlCl ate classified as super Lewis acids (211). By this definition, Lewis acids such as SbF, NbF, AsF, andTaF ate so categorized. 

Other oxides of phosphorus are less well characterized though the suboxide PO and the peroxide P2O6 seem to be definite compounds. PO was obtained as a brown cathodic deposit when a saturated solution of Et3NHCl in anhydrous POCI3 was electrolysed between Pt electrodes at 0°. Alternatively it can be made by the slow reaction of POBrs with Mg in Et20 under reflux ... 

Most of the work done in the pteridine series has been concerned with the equilibria between the neutral species and the anions. This work was more fruitful than that involving the cations because all three of the values, p /, p a , and pK/ (for definitions, see Section II, A), could be determined, and, from these, ratios of the hydrated to the anhydrous forms were calculated. Furthermore, the kinetics in the... 

Case definitions exist for the following agents anhydrous ammonia (C11-A061), arsenic trioxide (C11-A047), calcium arsenate (C11-A048), copper acetoarsenite (C11-A049),... 

A freshman chemist analyzed a sample of copper(II) sulfate pentahydrate for water of hydration by weighing the hydrate, heating it to convert it to anhydrous copper(II) sulfate, and then weighing the anhydride. The % H20 was determined to be 30%. The theoretical value is 33%. Which of the following choices is definitely NOT the cause of the error ... 

A commonly used and important reaction of sulfonic acids, or sulfonates, is their conversion to sulfonyl chlorides by treatment with phosphorus halides, or sometimes with thionyl chloride. Although it is easy to postulate mechanisms for this conversion, the exact path followed has never been determined. Similarly, although mechanisms can be suggested for other known reactions involving sulfonic acids, such as the cleavage of dialkyl ethers by anhydrous sulfonic acids (Klamann and Weyerstahl, 1965), or the formation of sulfones by treatment of an aromatic hydrocarbon with a mixture of sulfonic acid plus polyphosphoric acid (Graybill, 1967), nothing truly definitive is known about the details of the actual mechanisms of these reactions. 

Diammino-stannous Iodide, [Sn(NH3)2]I2, is obtained as a yellow powder by passing dry ammonia gas over anhydrous stannous iodide.2 By dissolving stannous iodide in liquid ammonia at a temperature of —78° C. a white crystalline substance separates containing ten molecules of ammonia. This, however, is not regarded as a definite compound, and from dissociation-pressure measurements it seems probable that pentammino-stannous iodide is the highest ammino-derivative which definitely exists. Diammino-stannous iodide, [Sn(NH3)2]I2, and monammino - stannous iodide, [Sn(NI-I3)]I2, arc coloured, the former yellow, the latter brown. The other ammines arc white. 

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