Gas carbon dioxide

The most common solvent employed is carbon dioxide gas, which can be injected between water spacers, a process known as WaterAlternating Gas (WAG). In most commercial schemes the gas is recovered and reinjected, sometimes with produced reservoir gas, after heavy hydrocarbons have been removed. Other solvents include nitrogen and methane. 

The basis of this process was the injection of sodium carbonate solution into the viscose, although direct injection of carbon dioxide gas that reacts with the viscose soda to form sodium carbonate could also be used (44). The carbonate route yielded a family of inflated fibers culminating in the absorbent multilimbed super inflated (SI) fiber (Eig. 5c). 

Ammonium bicarbonate, sp gr 1.586, formula wt 79.06, is the only compound in the NH —CO2—H2O system that dissolves in water without decomposition. SolubiUty in 100 g of H2O ranges from 11.9 g at 0°C to 59.2 g/100 g of H2O at 60°C (8). The heat of formation from gaseous ammonia and carbon dioxide andUquid water is 126.5 kj/mol (30.2 kcal/mol). Ammonium bicarbonate is manufactured by passing carbon dioxide gas... 

There are essentially two components in a chemical leavening system bicarbonate that suppHes carbon dioxide gas, and an acid which triggers the Hberation of carbon dioxide from bicarbonate upon contact with moisture (see Carbon dioxide). 

Precipitated Calcium Carbonate. Precipitated calcium carbonate can be produced by several methods but only the carbonation process is commercially used in the United States. Limestone is calcined in a kiln to obtain carbon dioxide and quicklime. The quicklime is mixed with water to produce a milk-of-lime. Dry hydrated lime can also be used as a feedstock. Carbon dioxide gas is bubbled through the milk-of-lime in a reactor known as a carbonator. Gassing continues until the calcium hydroxide has been converted to the carbonate. The end point can be monitored chemically or by pH measurements. Reaction conditions determine the type of crystal, the size of particles, and the size distribution produced. 

Carbon dioxide gas is added to either the water used to prepare beverages or the symp and water mixture, depending on the type of manufactuting equipment. In both manufactuting processes, the carbon dioxide gas is iatroduced under pressure to the system. The carbonation of the beverage is dependent on the carbon dioxide pressure and the temperature of the mixture. 

Sodium Phosphate Manufacturing. Some pure carbon dioxide gas is available as a by-product ia plants manufacturiag sodium phosphate from sodium carbonate [497-19-8] and phosphoric acid [7664-38-2]. Two carbon dioxide plants were iastalled prior to 1962 to utilize this by-product gas. 

Methods of Liquefaction and Solidification. Carbon dioxide may be Hquefted at any temperature between its triple poiat (216.6 K) and its critical poiat (304 K) by compressing it to the corresponding Hquefaction pressure, and removing the heat of condensation. There are two Hquefaction processes. In the first, the carbon dioxide is Hquefted near the critical temperature water is used for cooling. This process requires compression of the carbon dioxide gas to pressures of about 7600 kPa (75 atm). The gas from the final compression stage is cooled to about 305 K and then filtered to remove water and entrained lubricating oil. The filtered carbon dioxide gas is then Hquefted ia a water-cooled condenser. 

In addition to chemical synthesis and enhanced oil recovery, gaseous carbon dioxide is used in the carbonated beverage industry. Carbon dioxide gas under pressure is introduced into mbber and plastic mixes, and on pressure release a foamed product is produced. Carbon dioxide and inert gas mixtures rich in carbon dioxide are used to purge and fiH industrial equipment to prevent the formation of explosive gas mixtures. 

The use of carbon dioxide gas for shielded arc welding with semiautomatic microwire welding equipment has led to welding speeds up to 10 times those obtainable within conventional equipment. No cleaning or wire bmshing of the welds is required (45) (see Welding). 

Carbon dioxide gas is used to immobilize animals prior to slaughtering them (46). In addition to providing a humane slaughtering technique, this results in better quaHty meat. The CO2 increases the animal s blood pressure, thereby increasing blood recovery. The increased accuracy obtainable in the killing operation reduces meat losses because of cut shoulders. 

Carbonate Glasses. Carbonate glasses must be melted under moderate pressures to prevent the escape of carbon dioxide gas. The simplest carbonate glass forming system is K CO —MgCO. ... 

Other sources of sodium ion that are used to make sodium citrate are sodium carbonate and sodium bicarbonate. These reactions evolve large volumes of carbon dioxide gas, resulting in much foaming but less exotherm. 

Cosmetics and Toiletries. Citric acid and bicarbonate are used in effervescent type denture cleansers to provide agitation by reacting to form carbon dioxide gas. Citric acid is added to cosmetic formulations to adjust the pH, act as a buffer, and chelate metal ions preventing formulation discoloration and decomposition (213—218). 

In addition to linear chain extension, excess diisocyanate leads to cross-linking iato a network because the diisocyanate groups can also react with the hydrogen atoms of the —NH— groups ia the chains. Furthermore, the weU-known polyurethane foam mbber can be made by a dding water to the mixture because the isocyanate groups react vigorously with water to Hberate carbon dioxide gas as follows ... 

One cubic foot (0.03 cu.m) of methane requires 10 cubic feet (0.28 cu.m) of air (2cu.ft (0.06 cu.m) of oxygen and 8cu.ft (0.23 cu.m) of nitrogen) for combustion. The products are carbon dioxide, nitrogen, and water. The combustion product of one cubic foot of methane yields a total of nine cubic feet of carbon dioxide gas. Also, the gas burned contains some ethane, propane, and other hydrocarbons. The yield of inert combustion gas from burning a cubic foot of methane will be 9.33 cubic feet (0.26 cu.m)... 

Carbon dioxide gas ean aet as an asphyxiant due to displaeement of air, resulting in oxygen defieieney (page 262). Sourees inelude ... 

Liquid carbon dioxide is discussed on page 261. Carbon dioxide gas is commonly used for carbonating drinks, in fire extinguishers, for gas-shielding of welding and in shell moulding in foundries. Its physical and toxicological properties are summarized in Tables 8.5, 8.6 and 5.29. 

Chemical Reactivity - Reactivity with Water Slow, non-hazardous. Form carbon dioxide gas Reactivity with Common Materials data not available Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization May occur slowly. Is not hazardous Inhibitor of Polymerization Not pertinent. 

Carbon dioxide gas diluted with nitrogen is passed continuously across the surface of an agitated aqueous lime solution. Clouds of crystals first appear just beneath the gas-liquid interface, although soon disperse into the bulk liquid phase. This indicates that crystallization occurs predominantly at the gas-liquid interface due to the localized high supersaturation produced by the mass transfer limited chemical reaction. The transient mean size of crystals obtained as a function of agitation rate is shown in Figure 8.16. 

The liquid, after passing through the outlet valve, joined the line from another filter that was in u.se. It is believed that carbon dioxide gas from the filter liquid passed up the outlet line into the filter that was being inspected (Figure 11-2). A test showed that contamination was not sufficient to prevent a candle burning. ... 

A solution of sodium methoxide is prepared by adding 1.3 g (0.056 g-atom) of sodium in small pieces to 16 ml of carefully dried methanol in a small round-bottom flask. (Alternatively, 3.1 g of dry commercial sodium methoxide can be used.) To this solution is added 10 g of the previously isolated mixture of reaction products, and the flask is heated at reflux on a steam bath for 4 hours. Methanol and methyl carbonate are then distilled insofar as possible at steam-bath temperature from the clear yellow solution. The cooled cloudy solution is then washed with ether to remove neutral materials, and the desired product is precipitated from the alkaline solution by treatment with carbon dioxide gas. The material so obtained is collected by suction filtration and washed well with water. The slightly pink crystalline powder weighs 38-40 g (56-59 %). The material may be recrystallized from benzene or methanol, mp 163-164°. 

Carbon Dioxide Welding metal-arc welding in which a bare wire electrode is used, the arc and molten pool being shielded with carbon dioxide gas. 

Sodium carbonate is a white powder used in the manufacture of glass. When hydrochloric acid is added to a solution of sodium carbonate, carbon dioxide gas is formed (Figure 8.8). The equation for the reaction is... 

It is impossible to have liquid carbon dioxide at temperatures above 31°C, no matter how much pressure is applied. Even at pressures as high as 1000 atm, carbon dioxide gas does not liquefy at 35 or 40°C. This behavior is typical of all substances. There is a temperature, called the critical temperature, above which the liquid phase of a pure substance cannot exist The pressure that must be applied to cause condensation at that temperature is called the critical pressure. Quite simply, the critical pressure is the vapor pressure of the liquid at the critical temperature. 

At 25°C and 1 atm, this reaction does not occur. Witness the existence of the white cliffs of Dover and other limestone deposits over eons of time. However if the temperature is raised to about 1100 K, limestone decomposes to give off carbon dioxide gas at 1 atm. In other words, this endothermic reaction becomes spontaneous at high temperatures. This is true despite the fact that AH remains about 178 kj, nearly independent of temperature. 

Consider two closed glass containers of the same volume. One is filled with hydrogen gas, the other with carbon dioxide gas, both at room temperature and pressure. 

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