Dissolution of gases in liquids

Approximately 1.45 grams of CO2 (0.0329 mole) dissolves in a liter of water at 25°C and 

Oxygen, O2, is less soluble than CO2 in water, but it does dissolve to a noticeable extent due to dispersion forces (induced dipoles. Section 13-2). Only about 0.041 gram of O2 (1.3 X 10 mole) dissolves in a liter of water at 25°C and 1 atm pressure. This is sufficient to support aquatic life. 

The hydrogen halides, HF, HCI, HBr, and HI, are all polar covalent gases. In the gas phase the interactions among the widely separated molecules are not very strong, so solute-solute attractions are minimal. Due to the polarity of the hydrogen halides and the hydration of their ions, the dissolution processes in water are very exothermic. The resulting solutions, called hydrohalic acids, contain predominandy ionized HX (X = Cl, Br, I). The ionization myo[ es protonation of a water molecule hy HX to form a hydrated hydrogen ion, H30, and halide ion X (also hydrated). 

HF is only slightly ionized in aqueous solution because of its strong covalent bond. In addition, the polar covalent bond between H and the small F atoms in HF causes very strong hydrogen bonding between H2O and the largely intact HF molecules. 

In water. As H2O evaporates, blue CUSO4 5H2O orystals form. They are in dynamic equilibrium with the saturated solution. 

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Subject areas for the Series include solutions of electrolytes, liquid mixtures, chemical equilibria in solution, acid-base equilibria, vapour-liquid equilibria, liquid-liquid equilibria, solid-liquid equilibria, equilibria in analytical chemistry, dissolution of gases in liquids, dissolution and precipitation, solubility in cryogenic solvents, molten salt systems, solubility measurement techniques, solid solutions, reactions within the solid phase, ion transport reactions away from the interface (i.e. in homogeneous, bulk systems), liquid crystalline systems, solutions of macrocyclic compounds (including macrocyclic electrolytes), polymer systems, molecular dynamic simulations, structural chemistry of liquids and solutions, predictive techniques for properties of solutions, complex and multi-component solutions applications, of solution chemistry to materials and metallurgy (oxide solutions, alloys, mattes etc.), medical aspects of solubility, and environmental issues involving solution phenomena and homogeneous component phenomena. 

The solubility of gases in liquids is often treated as an equilibrium process. Take the dissolution of carbonyl sulphide (OCS) as an example ... 

Describe the dissolution of solids in liquids, liquids in liquids, and gases in liquids... 

Absorption an irreversible chemical retention effect on surfaces, either liquid or solid. Improperly applied to the dissolution (physical effect) of gases in liquids. 

The diffusivity of gases in liquids plays a role in gas injecting systems, when displacing an oil phase or expanding the oil by gas dissolution. In Figure 7.7, the amount of CO2 entering crude oil is depicted as a function of time. 

Examples of this type often occur in chemical and metallurgical processes the combustion and gasification of carbon and coal, the decomposition of solids into gases, the dissolution of solids in liquids, formation of metal carbonyls, fluorination and chlorination of metals, and some electrochemical processes. 

The composition of the subsurface gas phase may change as a result of gas dissolution into the liquid phase. The solubility of gases in water depends on the type of gas, temperature, salt concentration, and the partial pressure of the gases in the atmosphere. The most soluble gases are those that become ionized in water (CO, NHj, H S), while and are much less soluble (Table 1.2). 

Gas-liquid reactions form an integral part of the production of many bulk and specialty chemicals, such as the dissolution of gases for oxidations, chlorin-ations, sulfonations, nitrations, and hydrogenations. When the gaseous reactant must be transferred to the liquid phase, mass transfer can become the rate-limiting step. In this case, the use of high-intensity mixers (motionless mixers or ejectors) can increase the reaction rate. Conversely, for slow reactions a coarse dispersion of gas, as produced by a bubble column, will suffice. Because a large variety of equipment is available (bubble columns, sieve trays, stirred tanks, motionless mixers, ejectors, loop reactors, etc.), a criterion for equipment selection can be established and is dictated by the required rate of mass transfer between the phases. 

Corrosion can also occur by a direct chemical reaction of a metal with its environment such as the formation of a volatile oxide or compounds, the dissolution of metals in fused metal halides. The reaction of molybdenum with oxygen and the reaction of iron or aluminum with chlorine are typical examples of metal/gas chemical reactions. In these reactions, the metal surface stays film-free and there is no transport of electrical charge.1 Fontana and Staehle2 have stated that corrosion should include the reaction of metals, glasses, ionic solids, polymeric solids and composites with environments that embrace liquid metals, gases, aqueous and other nonaqueous solutions. 

Table VII gives the Henry s law coefficients of some atmospheric gases in liquid water at 298 K. The values given reflect only the physical solubility of the gas regardless of the subsequent fate of the dissolved species A. Some of the species included in Table VII dissociate after dissolution or react with water. The Henry s law constants of Table VII do not account for these processes, and the modifications necessary will be discussed in the next paragraph. Henry s law coefficients generally decrease for increasing temperatures, resulting in lower solubilities at higher temperatures (Seinfeld, 1986).

We next consider the dissolution of a mixture of gases in a liquid. We separate this situation into two different cases. First, if the concentrations of the dissolved gases in the liquid are relatively low, so that there are no nonideality departures from Henry s law, it is reasonable to assume that the solubility of each gas would be the same as if it were the only gas present at its gas-phase partial pressure. However, if the concentrations of the gases in the liquid are high enough that there are departures from the Henry s law limit, so that the activity coefficients yT need be included in the description, then the solubility of each species is affected by the presence of others through the values of the activity coefficients. 

The constituents of cloud water derive from two sources one is material incorporated with the condensation nuclei, the other is the dissolution of gases from the sm-rounding air. As the numbers of particles serving as cloud condensation nuclei are most numerous in the size range of the accumulation mode, cloud water generally represents a dilute solution of this fraction of the aerosol. But the components of the aerosol fraction are already fully oxidized and, therefore, not very reactive. On the other hand, many of the gases that dissolve in cloud water have a potential for further oxidation. The aqueous concentration of such substances depends on their abundance in the gas phase before cloud condensation sets in and on the individual gas-liquid (Henry s law) partition coefficients, which causes a redistribution of the substances between the two phases. The amoimt of liquid water in clouds is in the range 0.1-0.5 g/m , so that the volume of liquid... 

In order to make it possible the determination of enthalpies of solution of gases in organic liquid solvents, Battino and Marsh [70] set up a modified burette arrangement. This modified technique proved to be effective for the particular systems where small gas solubilities are observed. However the technique was impractical in the case of CO2 dissolution in aqueous solution of amine. This was mainly due to high solubility of carbon dioxide and consequently, large volumes of injected gas. Then Carson... 

Salts pH of hydrolysed solutions of, 431 Samples crushing and grinding of, 155 dissolution of, 110, 801 weighing of, 76, 110 see also Analysed samples Sampling 150 errors in, 153 hazards of, 155 of gases, 153 of liquids, 153 of solids, 153... 

Although, as described by Bjerle et alS13 liquid jet-type absorbers are also used, one relatively recent application of mass transfer in agitated tanks with chemical reaction is the absorption of pollutants from flue gases and, in particular, the scrubbing of sulphur dioxide by a slurry containing fine limestone particles. In this case, the concentration of sulphur dioxide is usually very low and the mechanism of the absorption is complicated due to the presence of solids in the liquid phase where the rate of solid dissolution may significantly affect the absorption rate. 

Permeation of gases, liquids, and vapors through a polymeric film can be looked at as a three-step process as follows (1) the rate of dissolution of the small molecules in the polymer, (2) the rate of diffusion of the small molecules in the polymer film in accordance with the concentration gradient, and (3) the energies of the smaller molecules on the opposite side of the polymer. 

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