Gases, collecting Measuring

Marqueyrol s Stability Test. 200g samples of double-base powds were heated at 50° under vac in a round bottom Pyrex flask. Every 3—4 days, the vapors were pumped out, collected in, a gasometer over Hg and measured. The test was contd until the powd started to decomp very rapidiy, usually after 1800—2000 days. A curve was then plotted of cc of gas evolved vs days of heating, and the gas was analyzed for C02 and NO. If any liq formed, it was collected, measured and analyzed... 

In the course of the electrolysis of water, hydrogen gas was collected at one electrode over water at 20.°C when the external pressure was 756.7 Torr. The vapor pressure of water at 20.°C is 17.54 Torr. The volume of the gas was measured to... 

The determination of acrylonitrile in air may be accomplished by collection on a solid sorbet, such as activated charcoal, followed by elution and gas chromatographic measurement (NIOSH 1984). 

Measure the mass, volume, temperature, and pressure of an insoluble gas collected over water. 

Results Most of the process-related, nonagent compounds present in the GPCR product gas are measured using a bubbler and standard EPA collection techniques. The process-related, nonagent compounds for which a method was not developed included vinyl sulfide, mercaptans, dimethylamine, and ethanethiol. 

There are many ways to measure the concentrations of reacting species or species formed during the reaction, such as there are gc, UV-visible spectroscopy, IR spectroscopy, refiactometry, polarometry, etc. Conversion can be monitored by pressure measurements, gas-flow measurements, calorimetry, etc. Data are collected on a computer and many programmes are available for data analysis [3,4], The two-reaction system described above can be treated graphically, if it fulfils either the Bodenstein or Michaelis-Menten criteria. 

Powder X-ray diffraction (XRD) data were collected via a Siemens D5005 diffractometer with CuKa radiation (A. = 1.5418 A). Routine transmission electron microscopy (TEM) and Z-contrast microscopy were carried out using an HITACH HD-2000 scanning transmission electron microscope (STEM) operated at 200 kV. Nitrogen gas adsorption measurements (Micromeritics Gemini) were used to determine the surface area and porosity of the catalyst supports. Inductively coupled plasma (ICP) analysis was performed via an IRIS Intrepid II XSP spectrometer (Thermo Electron Corporation). 

If Rayleigh s measurements had not been performed with care, this difference might have been attributed to experimental error. Instead, Rayleigh understood that the discrepancy was outside his margin of error, and he postulated that gas collected from the air was a mixture of nitrogen with a small amount of a heavier gas, which turned out to be argon. 

Direct sampling and analysis of the effluent stream may be used to determine the solubility of the heavy phase in the volatile component (often a supercritical fluid). Alternatively, the composition can be determined from the total volume of gas (i.e., of the supercritical fluid after expansion) passed through the saturator, and from the known mass of solute extracted during die sample-collecting period. The efflluent stream is expanded to atmospheric pressure via an expansion valve. Then it passes through a cold trap, where the extract is quantitatively precipitated or condensed, and finally proceeds to a dry-test or a wet-test gas meter or other device, where the total amount of the passed gas is measured. The amount of extracted solute... 

AES are typically measured in environmental matrices by nonspecific colorimetric analyses (MBAS) that collectively measure LAS, AS, and naturally occurring anionic surfactants. Alternatively, a specific gas chromatographic method for AES, developed by Neubecker (55), was employed to measure AES concentrations in influent and effluent from STPs and river water. Total AES measured in influent wastewater to a STP was 1.88 mg/L. AES removal of 94-100% was measured during actual sewage treatment by activated sludge the resulting effluent concentration was 0.06 mg/L. Total AES levels in river water were less than 0.01 mg/L. AES accounted for 6-13% of MBAS measured in natural water. 

The mass spectra of the gases evolved from the deuterated SWNT sample heated in vacuum were measured with the MI 1201V mass spectrometer. Gas ionization in the ion source of the spectrometer was produced with a 70-eV electron beam. To obtain the gas phase, the sample was placed in a quartz ampoule of a pyrolyzer that was connected to the injection system of the mass spectrometer through a fine control valve. Then the ampoule was evacuated to a pressure of about 2-x 10-5 Pa in order to remove the surface and weakly bound impurities from the sample. After the evacuation, the ampoule was isolated from the vacuum system and the sample was heated to 550°C in five steps. At each step, the sample was kept at a fixed temperature for 3 h then the fine control valve was open and the mass-spectrometric analysis of the gas collected in the ampoule was performed. After the analysis, the quartz ampoule was again evacuated, the valve was closed, and the sample was heated to the next temperature. The measurements were carried out over the range 1 < m/z < 90, where m is the atomic mass and z is the ion charge. The spectrometer resolution of about 0.08% ensured a reliable determination of the gas-phase components. 

When no further bubbles rise into the measuring cylinder record the volume of gas collected. 

At the conclusion of each experiment the gas and fuel flow were stopped, the collection system was isolated, evacuated and allowed to warm to room temperature and the volume of condensed gas was measured. 

Adjust an accurately weighed sample, as needed, with 20% aqueous sodium chloride to obtain a Sample Solution with a solids content of 36%. Transfer a 20-g aliquot of the Sample Solution into a 20-mL Extrelut NT column (EM Science, Gibbstown, NJ), or equivalent, and allow it to equilibrate for 15 min. Elute the column with 150 mL of ethyl acetate, collecting the eluent in a 250-mL short-neck, round-bottom flask with a 24/40 joint. Using a rotary evaporator at 50°, concentrate the eluent to a volume of approximately 3 mL. Add 0.5 mL of Internal Standard Solution to the eluent, transfer this mixture to a 4-dram screw-cap vial, and dilute to a volume of 5.0 mL. Inject 1 pL into the gas chromatograph, measure its response area ratio of 3-CPD to the Internal Standard Solution, and determine from the standard curve the micrograms of 3-CPD in the 20-g aliquot taken. l,3-Dichloro-2-propanol (DCP)... 

A steady gas flow calibrating a flow meter of this kind can be obtained from a needle valve attached to a regulator set to 5- 10 psi gauge pressure or more (to avoid perturbations due to small variations in outlet pressure). At small flow rates the volume of gas flow over an interval of time measured with a timer can be determined with a gas burette a three-way stopcock can be used to switch the gas burette in and out of the system. For larger flow rates a water-filled inverted graduated cylinder or volumetric flask, its mouth held under the surface of a water bath, can be used to collect gas from a rubber tube held underneath it for a time interval measured with a timer. For precise work, a correction should be made for the partial pressure of water vapor in the gas collected. 

He) was introduced into the column, and the column pressure reached the adsorption pressure Pa. This process took about 5 seconds. Valve V-2 was then opened, and adsorption in the column from the inlet gas took place (adsorption step). During this period, the flow rate and concentration of CO, Gu and C/ were measured. (2) Valves V-1 and V-2 were closed, V-4 was opened, and the column was evacuated (desorption step). At the end of the desorption step, the pressure was below 13 Pa after 600 seconds. (3) As V-3 was also opened under evacuation, helium was supplied as a countercurrent puige to remove CO thoroughly (countercurrent purge step). (4) With V-3 closed and V-4 still open, the column was re-pressurized to the adsorption pressure with helium. The measurement conditions are summarized in Table 1, and the samples that were screened are listed in Table 2. The adsorption temperature was one parameter examined in this study, and a sequence controller was programmed for each set of conditions, so that steps (1) ( 4) were repeated over more than 4 hours. The total amount of desorbed gas was determined from the gas collected at the exit of the rotary flowm er. 

Discussion of sampling techniques must involve both free and bound gases. To facilitate this discussion the collection, measurement and analysis of light (C1-C4) hydrocarbons will be broken into two main categories each with two subcategories (1) free gas, which can be vapour or dissolved gas and (2) bound gas, which can be adsorbed gas or chemi-adsorbed gas. 

A gas collected over water at 25 C becomes saturated with water vapor, its partial pressure being 23.8 mm. The measured volume of the moist gas is 5.44 liters, at a total pressure of 752.0 mm. Calculate the volume the dry gas would occupy at a pressure of 760 mm., assuming ideal behavior of the gas and of the water vapor. 

The relevant point here is that a gas collected over water is moist that is, it is saturated with water vapor. Measuring the atmospheric pressure at which the gas is collected, we can write... 

Soil gas collecting tubes and lysometers to sample soil waters were installed at four locations above sampled drips in Cascade Cave (sites 16 and 17) and X Cave (sites 18 and 19) as shown on Fig. 3. Pco, measured from the gas wells and equilibrium Pco, in the water withdrawn from the lysometers was higher during the summer when plant growth was active and soil temperatures were high, and at any one time increased with depth. The Pco, of sandy soUs with higher permeability tended to be lower than clayey soils, and deep drying of the soils caused a decline in Pco, Some representative values are shown in Table II. 

Gas and liquid are mixed before entering the reactor bed in a gas-liquid chamber 17 at the inlet of the reactor. The gas leaving the reactor flows through a condenser 18, where evaporated solvent is condensed, and then to the gas-liquid separator 19. The condensed solvent is collected in a separate buffer vessel 20 and returned to the reactor if necessary, the gas leaves the system through a backpressure valve controlling the pressure in the system. The volumetric flow of the effluent gas is measured with a gas meter 21. 

The solubility of relatively nonvolatile components (including solids) in a gas may be measured by the gas saturation method mentioned in Section 1.8.5. The gas is passed through the solute, and the amount of solute collected by a given amount of gas is measured. This method is commonly used to measure solubilities in supercritical fluids, where the effects of pressure and vapor-phase nonideality make the partial pressure of the solute in the vapor much larger than its vapor pressure. The major challenges are analysis of the solute collected, avoiding condensation of the solute before it is collected, and ensuring that all the gas is saturated with the solute. 

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