Pressure of argon

By introducing a collision gas into Q2, collision-induced dissociation (CID) can be used to cause more ions to fragment (Figure 33.4). For example, with a pressure of argon in Q2, normal ions (mj ) collide with gas molecules and dissociate to give mj ions. CID increases the yield of fragments compared with natural formation of metastable ions without induced decomposition. 

A dry 1-L, three-necked, round-bottomed flask equipped with a large Teflon-covered magnetic stirring bar, a thermometer, and a dry ice condenser (Note 1) is flushed with argon (Note 2), then capped with a serun stopper and subsequently maintained under a positive pressure of argon (Note 3). A 30 dispersion of lithium metal (in mineral oil) containing 1% sodium (13.9 g, 2.00 g-atom of lithium) (Note 4) is rapidly weighed and transferred to the flask. 

A slight positive pressure of argon was maintained in the vessel throughout the reaction by using an argon line connected to both a bubbler containing Nujol and the inlet on the dry ice condenser. 

An example is the complex with argon which can be kept indefinitely in an ordinary bottle, although the equilibrium pressure of argon over the crystal amounts to several atmospheres at room temperature. Powell31 named these complexes "clathrate compounds, which according to him are those compounds "in which two or more components are associated without ordinary chemical union but through complete enclosure of one set of molecules in a suitable structure formed by another. ... 

The radii av a2 and coordination numbers zv z2 follow from x-ray analysis (cf. Section I.B), and aQ/2 — 1.25 A corresponds to Pauling s van der Waals radius of 1.40 A for a covalently bound oxygen atom.25 The value of eQlk — 166.9°K was chosen to obtain agreement between calculated and experimental values of the equilibrium vapor pressure of argon hydrate at 0°C. 

DEAE-cellulose chromatography. The 50% ethanol solution is poured onto a column of DEAE cellulose (2.6 x 10 cm), and F adsorbed at the top is eluted with 20 mM Tris buffer, pH 7.5, containing 0.2 M NaCl. A low pressure of argon gas is applied to accelerate the flow rate. The fractions containing F are combined, concentrated, and desalted using ethanol. 

In a 250-ml., three-necked, round-bottomed flask equipped with a mechanical stirrer, a gas inlet, and a stopper are placed 540 mg. (0.00346 mole) of a mixture of cis- and dimethyl sulfoxide (Note 3). While a slight positive pressure of argon is maintained... 

Dichloromethane (unstabilized HPLC grade) was purchased from Fisher Scientific and was dried by percolation through two columns packed with neutral alumina under a positive pressure of argon. 

B. 2-Cyclopentylacetophenone (2). A 500-mL, two-necked, round-bottomed flask (Note 11) equipped with an egg-shaped magnetic stir bar (4 cm x 1.5 cm), argon inlet adapter, and a rubber septum is flame-dried and allowed to cool to room temperature under a positive pressure of argon. A thermometer is inserted through the septum (Note 12) and the flask is charged with 114 mL of dry,... 

The drawing below shows a tiny section of a flask containing two gases. The orange spheres represent atoms of neon and the blue spheres represent atoms of argon, (a) If the partial pressure of neon in this mixture is 420. Torr, what is the partial pressure of argon (b) What is the total pressure ... 

In the atmosphere, the partial pressure of argon is PAl = 0.00934 atm. (Recall that pressure fractions equal volume fractions for ideal gases.) We now compute the concentration of argon in aqueous solution. 

The reaction was performed in flame-dried modified Schlenk (Kjeldahl shape) flask fitted with a glass stopper or rubber septum under a positive pressure of argon. Trifluoromethanesulfonic anhydride (1.4 equiv) was added to a solution of giycosyl donor (0.191 mmol, 1 equiv) and diphenyl sulfoxide (2.8 equiv) in a mixture of toluene and dichloromethane (8 ml, 3 1 vol/vol) at — 78 °C. The reaction mixture was stirred at this temperature for 5 min and then at —40 °C for 1 h. At this time, 2-chloropyridine (5.0 equiv) and the giycosyl acceptor (3.0 equiv) were added sequentially at —40 °C. The solution was stirred at this temperature for 1 h, then at 0 °C for 30 min and finally at 23 °C for lh before the addition of excess triethylamine (10 equiv). The reaction was diluted with dichloromethane (100 ml) and was washed sequentially with saturated aqueous sodium bicarbonate solution (2 x 100 ml) and saturated aqueous sodium chloride (100 ml). The organic layer was dried (sodium sulfate) and concentrated. The residue was purified by silica gel flash column chromatography. 

The pressure of argon gas during atomization ranges from 0.03 to 0.1 MPa. The crucible diameter is 75 mm and its rotating speed is up to 400 radians/s. This combination of conditions gives a production rate up to 1 kg/min, l89l The CSC-atomized particles are either spherical or flaky. Spherical particles usually have smooth... 

A slight positive pressure of argon is maintained throughout the reaction. 

Henry and McUmber (1977) reported on the systems R-22 -water and R-22-oil. They constructed an apparatus in which R-22 could be poured into water or mineral oil at various ambient pressures controlled by the pressure of argon gas in the system. Separate units were used for the water and oil tests. They demonstrated that they could achieve thermal explosions at 1 bar, in agreement with earlier tests (see Section VII). However, no such events were observed at system pressures of 2.2 or 8 bar even though the hot liquid temperature was varied over a wide range. 

In the third study, Miyazaki and Henry (1978) carried out vapor bubble growth experiments with water drops in hot silicone oil under various pressures of argon gas. As conducted, the oil temperature was set so that the interface temperature was below the homogeneous nucleation temperature of water. When bubbles did appear, their growth was followed by... 

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