Bulb method

A number of synthetic procedures are available (Ai2). (2) For precisely defined stoichiometries, the isobaric, two-bulb method of Herold is preferred H5, H6, H2). (2) To generate compounds suitable for organic synthesis work, graphite and alkali metal may be directly combined, and heated under inert gas (Pl, lA). (5) Electrolysis of fused melts has been reported to be effective iN2). 4) Although alkali metal -amine solutions will react with graphite, solvent molecules co-inter-calate with the alkali metal. Utilization of alkali metal-aromatic radical anion solutions suffers the same problem. 

First-stage intercalation conpoimds of FeCla were prepared and characterized by a variety of techniques (5.33). Two distinct preparation procedures were used (see scheme/ from vapour, using the established "two-bulb" method and from solution ising U.V. li t (see Experimental). 

Transient Diffusion of Ideal Gaseous Mixtures in Two Bulb Method... 

So far we have analysed the two systems using the Maxwell-Stefan approach the steady state analysis of the Stefan tube and the transient analysis of the Loschmidt s tube, and they are conveniently used to study the diffusion characteristic of the system. Here, we consider another example which is also useful in the determination of diffusion characteristics. This system is the two bulb method, in which a small capillary tube or a bundle of capillaries is bounded by two well-mixed reservoirs as shown in Figure 7.2-3. 

Transient diffusion of ideal gaseous mixtures in two bulb method 457... 

The molar mass of a volatile substance was determined by the Dumas-bulb method described in Exercise 10.53. The unknown vapor had a mass of 0.846 g the volume of the bulb was 354 cm, pressure 752 torr, and temperature 100 °C. Calculate the molar mass of the unknown vapor. 

A useful method often used is the two-bulb method (Nl). The apparatus consists of two glass bulbs with volumes Fj and V2 m connected by a capillary of cross-sectional area A m and length L whose volume is small compared to and V2, as shown in Fig. 6.2-4. Pure gas A is added to Kj and pure B to Fj at the same pressures. The valve is opened, diffusion proceeds for a given time, and then the valve is closed and the mixed contents of each chamber are sampled separately. 

Figure 6.2-4. Diffusivity measurement of gases by the two-bulb method.

Figure 16 gives the NPSH versus liquid level plotted on the same scale at the inlet of the pump as was measured by the NBS vapor bulb method, Note that the NPSH is much less than the liquid level, At about 23 inches of liquid level, it has disappeared. This is expected from the relatively high heat leak from the plug opening in the bottom of the test dewar. 

MOLECULAR WEIGHT FROM GAS DENSITY (THE DUMAS BULB METHOD)... 

The twin-bulb method of measuring diffusion is shown below. The bulbs, which are stirred and of equal volume, initially contain binary gas mixtures of different compositions. At time zero, the valve is opened at time t, the valve is closed, and the bulk contents are analyzed. Explain how this information can be used to calculate the diffusion coefficient in this binary gas mixture. 

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