Rast method

The Rast method uses camphor (Ci0Hi O) as a solvent for determining the molar mass of a compound. When 2.50 g of cortisone acetate is dissolved in 50.00 g of camphor (kf = 40.0°C/m), the freezing point of the mixture is determined to be 173.44°C that of pure camphor is 178.40°C. What is the molar mass of cortisone acetate ... 

Rast method analy chem The melting-point depression method often used for the determination of the molecular weight of organic compounds. rast. meth-od rate constant physchem Numerical constant in a rate-of-reaction equation for example, = feCaACbBCcC, where and Cc are reactant concentrations, k is the... 

Other studies have indicated respiratory effects from chronic exposure to HDL The radioallergosorbent test (RAST) method and skin tests were used to evaluate the significance of type I sensitization, its incidence, and relationship to respiratory dysfunctions in a large population of isocyanate-exposed workers. A group of 621 workers engaged in isocyanate processing for a period of 2 weeks to 40 years were studied. Sex of the workers was not reported. Of these workers, 183 had contact with TDI ... 

Sometimes camphor is used as the solvent (Rast method) because of its high constant ( 38). However, it is very prone to form solid solutions which vitiate this method of determining molecular weights, since it is based on the assumption that the first solid to be deposited will be the pure solvent. The use of camphor and related solvents is therefore not recommended. The possibility of obtaining solid solutions should be recognized in all cases, for this is one of the main limitations to the use of this method. 

The Rast method for determining molar masses uses camphor as the solvent. Camphor melts at 178.4°C, and its large Kf (37.7 K kg mol ) makes it especially useful for accurate work. A sample of an unknown substance that weighs 0.840 g reduces the freezing point of 25.0 g of camphor to 170.8°C. What is its molar mass ... 

Rast method. The melting-point depression method often used for the determination of the molecular weight of organic compounds. 

Azaboratricycloundecane (4) is monomeric in the gas phase and associated in nonpolar solvents (hexameric, as estimated by the Rast method). Its vapor pressure corresponds to the equation log P(mm) = 8.743 — 2845/r, from which the heat of vaporization is 13.02 kcal mol <64JCS4753>. 

Molecular weights (determined by the Rast method) are also found to depend on the cooling schedule, and data have been reported in this area [19]. 

III. Depression of the Freezing-point of Camphor (Rast s Method). 

Molecular extinction coefficients, 1135 Molecular weight, by Rast camphor method, 1037 Molisch test, 453 ... 

The Analytical section has been subjected to some changes. An electrically heated combustion furnace, some new methods of analysis, and the method of Rast for the determination of molecular weights, are also described. Chapter XLIV. on tests for some common organic substances has been completely rewritten. 

Extensive fragmentation of the allergic extracts has been demonstrated to occur in the duodenum [46, 47], whereas some data suggest partial degradation due to saliva (using the RAST inhibition method) [47], We evaluated the gel... 

A new treatment for S = 7/2 systems has been undertaken by Rast and coworkers [78, 79]. They assume that in complexes with ligands like DTPA, the crystal field symmetry for Gd3+ produces a static ZFS, and construct a spin Hamiltonian that explicitly considers the random rotational motion of the molecular complex. They identify a magnitude for this static ZFS, called a2, and a correlation time for the rotational motion, called rr. They also construct a dynamic or transient ZFS with a simple correlation function of the form (BT)2 e t/TV. Analyzing the two Hamiltonians (Rast s and HL), it can be shown that at the level of second order, Rast s parameter a2 is exactly equivalent to the parameter A. The method has been applied to the analysis of the frequency dependence of the line width (ABpp) of GdDTPA. These results are compared to a HL treatment by Clarkson et al. in Table 2. 

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