Gases in Water

The solubihty of a gas in water is affected by temperature, total pressure, the presence of other dissolved materials, and the molecular nature of the gas. Oxygen solubihty is inversely proportional to the water temperature and, at a given temperature, directly proportional to the partial pressure of the oxygen in contact with the water. Under equihbrium conditions, Henry s law apphes... 

Ga.s Eeeders. Chlorine gas is usually fed from a chlorine cylinder equipped with a pressure gauge, reducing valve, regulating valve, feed-rate indicator, and aspirator-type injector for dissolving the chlorine gas in water. The feeder can be manually, or more desirably automatically, controlled utili2ing continuous amperometric or potentiometric measurement of the free chlorine residual. The chlorine solution is normally introduced into the return line to the filter. 

Hypochlorous Acid—Sodium Chlorite System. In this method, chlorine gas is educted into water forming a hypochlorous acid solution which then reacts with aqueous sodium chlorite to produce chlorine dioxide (114—116). Hypochlorous acid, formed from the disproportionation of chlorine gas in water ... 

Recovery as liquid sulfur dioxide (absorption of clean dry off-gas in water or chemical absorbtion by ammonium bisulfite or dimethyl aniline),... 

Physical absorption The process of collecting a gas in water or another fluid. 

An existing lO-in. I.D. packed tower using 1-inch Berl saddles is to absorb a vent gas in water at 85°F. Laboratory data show the Henry s Law expression for solubility to be y = 1.5x, where y is the equilibrium mol fraction of the gas over water at compositions of x mol fraction of gas dissolved in the liquid phase. Past experience indicates that the Hog for air-water system will be acceptable. The conditions are (refer to Figure 9-68). 

Entrained gas and air expands under the reduced pressure of the suction stroke, lowering the suction efficiency. Gas in water-base mud may also deteriorate the natural rubber parts used. Gases are usually separated with baffles or by changing mud composition. 

Toxoid vaccines. Toxoid vaccines are preparations derived fiom the toxins that are seereted by eertain species of bacteria, hi the manufacture of such vaccines, the toxin is separated fiem the bacteria and treated in a way that eliminates toxicity without eliminating immunogenicity. Formalin (ca. 38% of formaldehyde gas in water) is used for this purpose and consequently the treated toxins are often referred to as formol toxoids. Toxoid vaccines are veiy effective in the prevention of those diseases such as diphtheria and tetanus in which the harmful effects of the infecting bacteria are due to the deleterious action of bacterial toxins on physiology and biochemistry. 

Gel-like soft crystals, which form in the bulk of liquid water at a defl-ciency of dissolved gas in water... 

Persistency The persistency will depend upon munitions used and the weather, ffeavily splashed liquid persists 1-2 days under average weather condition. GA evaporates about 20x more slowly than water. GA in water can persist about 1 day at 20°C and about 6 days at 5°C. GA persists about twice as long in seawater. 

Hydrochloric acid is made by dissolving hydrogen chloride gas in water. Hydrogen chloride is a colorless, poisonous gas at room temperature but it can be an extremely useful compound when dissolved in water to make hydrochloric acid. 

Both of these facts are employed in the carbonation process of sodas and beer and some sparkling wines. Low-temperature conditions and CO2 pressures of 3 to 4 atm are used to enhance the dissolution of carbon dioxide gas in water. The graph in Fig. 3.1.1 presents the solubility of carbon dioxide in water at various temperatures and pressures. The parameter used to express CO2 solubility is... 

An alternative explanation follows. The process of the gas coming out of solution is endothermic (heat is required). (We know this to be true because the reaction solution of gas in water -> gas + liquid water proceeds to the right as the temperature is raised, a characteristic direction of an endothermic reaction.) The required heat is taken from the cooled liquid, causing it to freeze. 

Chlorine (Cl), 6 130-211 9 280. See also Inorganic chlorine XeCl laser addition to fullerene, 12 240-241 analytical methods, 6 202 bleaching agent, 4 50 capacities of facilities, 6 193-198t catalyst poison, 5 257t chemical properties, 6 133-138 diffusion coefficient for dilute gas in water at 20° C, l 67t diffusion coefficient in air at 0° C, l 70t for disinfection, 8 605 economic aspects, 6 188-202 electrolytic preparation/production of, 12 759 16 40 end uses, 6 134-135 in fused quartz manufacture, 22 413 generating from hydrogen chloride, 13 833... 

The readings obtained reflect the rate of the reaction and in many cases are sufficient although they may not give the quantitative information regarding the amount of gas evolved. For quantitative work, it is necessary to determine the flask constant (k), which takes into account the total gas volume of the system, the solubility of the gas in water and the absolute temperature of the reaction. This factor can then be used to convert the pressure readings into gas volume. 

Hypochlorous acid, HOCl, is a weak acid that is found in household bleach. It is made by dissolving chlorine gas in water. 

A realistic boundary condition must account for the solubility of the gas in the mucus layer. Because ambient and most experimental concentrations of pollutant gases are very low, Henry s law (y Hx) can be used to relate the gas- and liquid-phase concentrations of the pollutant gas at equilibrium. Here y is the partial pressure of the pollutant in the gas phase expressed as a mole fraction at a total pressure of 1 atm x is the mole fraction of absorbed gas in the liquid and H is the Henry s law constant. Gases with high solubilities have low H value. When experimental data for solubility in lung fluid are unavailable, the Henry s law constant for the gas in water at 37 C can be used (see Table 7-1). Gas-absorption experiments in airway models lined with water-saturated filter paper gave results for the general sites of uptake of sulfur dioxide... 

Sulfurous acid (H SOj) can be produced by burning sulfur to form sulfur dioxide (SOj) gas and by then dissolving the gas in water to form sulfurous acid. This is the acid produced by burning coal that has a high sulfur content the gaseous sulfur dioxide by-product of combustion then combines with atmospheric water to form acid rain. ... 

Helium is a colorless, odorless, and tasteless inert gas that is noncombustible and is the least soluble of any gas in water and alcohol. As a gas, it diffuses well in sohds. Hehum s freezing point is -272.2°C, and its boiling point is -268.93°C. Both temperatures are near absolute zero (-273.13°C, or-459.4°F), where all molecular and thermal motion ceases. Liquid helium has the lowest temperature of any known substance. Heliums density is 0.0001785g/cm. ... 

The simplest of the aldehydes is formaldehyde, whose molecular formula is HCHO. The second hydrocarbon backbone of the ketone is replaced by a hydrogen atom. Formaldehyde is a gas that is extremely soluble in water it is often sold commercially as a 50 percent solution of the gas in water. The gas itself is flammable, has an ignition temperature of 806°F and a strong, pungent odor, and is toxic by inhalation. Inhalation at low concentrations over long periods of time has produced illness in many people. Beside its use as an embalming fluid, formaldehyde is used in the production of many plastics and in the production of numerous other chemicals. 

Furthermore, the solubility of gases in liquids decreases with rising temperature. Accordingly, the concentration of a dissolved gas in water can be reduced simply by vacuum degassing or by heating. Alternatively, one can resort to specific chemical methods of removal.18,19... 

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