Cryoscopy

Used (particularly He, Ar) to provide an inert atmosphere, e.g. for welding, and in electric light bulbs, valves and discharge tubes (particularly Ne). Liquid He is used in cryoscopy. The amounts of He and Ar formed in minerals by radioactive decay can be used to determine the age of the specimen. Xe and to a lesser extent Kr and Rn have a chemistry the other noble gases do not form chemical compounds. 

Solutions of dinitrogen tetroxide (the mixed anhydride of nitric and nitrous acids) in sulphuric acid are nitrating agents ( 4.3.2), and there is no doubt that the effective reagent is the nitronium ion. Its formation has been demonstrated by Raman spectroscopy and by cryoscopy ... 

Among the techniques employed to estimate the average molecular weight distribution of polymers are end-group analysis, dilute solution viscosity, reduction in vapor pressure, ebuUiometry, cryoscopy, vapor pressure osmometry, fractionation, hplc, phase distribution chromatography, field flow fractionation, and gel-permeation chromatography (gpc). For routine analysis of SBR polymers, gpc is widely accepted. Table 1 lists a number of physical properties of SBR (random) compared to natural mbber, solution polybutadiene, and SB block copolymer. 

On his return to Princeton after the war, Hugh Taylor organized catalytic research at the Frick Chemical Laboratory. He applied high vacuum technique, liquid air cryoscopy to the study of adsorptive characteristics of catalysts, correlating rates of catalytic reactions and rates of adsorption. He introduced the concept of activated adsorption and defended it against all comers. ... 

Step 3 Determine the molar mass of the solute by dividing the given mass of solute, wso)ute (in grams), by its amount (step 2), as in the procedure for cryoscopy. 

The oxidation of IV.AT-diphenylhydroxylamine with silver oxide produces a red substance shown to be a completely dissociated radical by its color (unchanged at —50°), by cryoscopy in benzene, and by its paramagnetism.140 Its reactions are typical of free radicals.141... 

Used industrially for the manufacture of organophosphorus compounds (Insecticides, dyes, pharmaceuticals, defoliants) as well as esters for plasticizers, gasoline additives, and hydraulic fluids used in industry as a chlorinating agent, catalyst, dopant for semiconductor grade silicon, fire retarding agent, and solvent in cryoscopy. 

The related tertiary phosphines PMe3 and PMe2Ph may also be met-alated by BunLi(tmeda), giving phosphinomethanide complexes that are shown by cryoscopy to be monomeric in benzene solution, but that crystallography confirms are dimeric in the solid state (126). Both complexes crystallize as dimers, [Li(CH2PMeR)(tmeda)]2 [R = Me (40), Ph (41)], with a similar structure to that of 39, containing a (CPLi)2 core. However, whereas 40 adopts a chair conformation, 41 is closer to a boat conformation with the phenyl groups in equatorial... 

The word cryoscopy comes from the Greek kryos, which literally means frost. ... 

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