Vapor pressure titrations

The stiochiometry of the reaction was measured by reacting Pu metal with a THF solution of C2Rll2 in a sealed, evacuated flank. After 24 hours, volume and pressure measurements showed that 1.46 mm of gas was evolved, after correction for the vapor pressure of THF 1.54 mm of Pu was consumed, and titration of the THF filtrate found 1.8 mm of iodine. The gas composition was not determined, but assuming that the evolved gas was C H, these data indicate that the reaction is ... 

I.r. spectra 4,13) and measurements of vapor pressure 4) indicate strong inter-molecular hydrogen bridging. In contrast to concentrated H2SO4 difluorophosphoric acid is a base and can be titrated conductometrically 14) ... 

It is also possible that the analyte must be calculated from a gaseous product of another reaction. In this case, one would want the gas to react with the titrant as soon as it is formed, since it could escape into the air because of a high vapor pressure. Thus an excess of the titrant would be present in a solution through which the gas is bubbled. After the gas-forming reaction has stopped, the excess titrant in this bubble flask could be titrated with the back titrant and the results calculated. This latter experiment is one form of the Kjeldahl titration. 

Most of the work on the boric acid-diol reaction during the last twenty years has been done to determine the coordination number of the diol (number of diol molecules) in the complex and to evaluate the equilibrium constant (often called a stability constant) for a number of diol-boric acid reactions. Several techniques have been used to study these questions, including polarimetry (7), optical rotatory dispersion (8), polarography (9), conductivity (3), vapor pressure osmometry (10), and electrochemistry (II, 12, 13). The most frequently studied system has been the electrochemical (pH) titration of boric acid or borax solutions with various diols. 

Fig. 9.4. Typical tensimetric titration curve. Total pressure in the tensimeter is plotted against the mole ratio of BFj added to reactant. In this case the solvent was toluene which was maintained at — 78°C for each pressure measurement. The horizontal portion of the pressure curve originates from the low toluene vapor pressure at this temperature. Above the I i ratio of reactants, excess BFj is present and the pressure increases steadily with each addition of BFj.

Vapor Pressure Measurements. Total vapor pressures were measured at 30°C with a Texas Instruments quartz spiral gauge. The procedure used was similar to that given previously (5). The concentration of water after the experiment was checked by Karl Fischer titration, while that of ether was found by weighing the cell before and after the vapor pressure determination the loss of weight was that of ether. Since Sb( V) interferes with the Karl Fischer titration of water, the water concentration in the HSbClG solutions was also obtained from the loss of weight of the cell. 

Ideal solution a solution whose vapor pressure is directly proportional to the mole fraction of solvent present. (17.4) Indicator a chemical that changes color and is used to mark the endpoint of a titration. (4.9 8.5)... 

A linear polyester was synthesized from a mixture of diacid and glycol with carboxyl to hydroxyl ratio greater than unity. A sample of the polyester (3.5 g) requires titration with 23 mL of N/50 KOH to reach a phenolphthalein end point. By vapor-pressure osmometry the molecular weight of the polymer was determined to be 12,000. Calculate the average carbo]tyl hmctionality of the polymer (that is, average number of carboxyl groups per polymer molecule). 

Fraction Viscosity Osmotic Vapor Pressure End Groups Titration Number of Monomers Specific Activity gC/mg... 

The choice of a concentration unit is based on the purpose of the measurement. For instance, the mole fraction is not used to express the concentrations of solutions for titrations and gravimetric analyses, but it is appropriate for calculating partial pressures of gases (see Section 5.6) and for dealing with vapor pressures of solutions (to be discussed later in this chapter). 

A great deal of equipment has been devised for work with liquefied gases, such as NH3, SO3, HF and others. This equipment permits carrying out such operations as precipitation, filtration, washing, drying, titration, etc., in complete absence of air and moisture. The operations proceed either in vacuum at the vapor pressure of the particular liquefied gas or in an inert atmosphere. The following brief description of equipment cannot make any claim to conq)leteness. 

In the analytical procedure the CTPnBA was separated from the excess initiator, chain transfer agent and monomeric nBA in a cleaning method which included several stages. Appendix A. The molecular weight of the purified CTFnBA rubber was measured by a Knauer Vapor Pressure Osmometer in chloroform solution at 37 C. The carboxyl content of the CTPnBA was determined by a chemical titration procedure using a modified potentlometrlc technique. Appendix B. 

Functionality. The number of carboxyl equivalents was determined from the potentlometrlc acid-base titration. The number molecular weight iii of the CTPnBA was determined by the Vapor Pressure Osmometer measurement. The product of the number of acid equivalents by the molecular weight divided by the weight of the titrated PnBA sample is the calculated average number of carboxyl groups per chain of the poly n-butyl acrylate. 

K Vapor pressure osmometry End-group titration Proton NMR Boiling point elevation Freezing depression (cryoscopy) GPC... 

Methods for the number-average molecular weight, M CR, cryoscopy EB, ebullioscopy EG, end-group titration OS, osmotic pressure VOS, vapor pressure osmometry. 

Iodine, even bound to iodide as l3, is bmely soluble in water and has a significant vapor pressure. Again, speed of titration is essential. 

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