Carbon dioxide in air

The characteristics for aqueous KOH (97—99) solutions vary somewhat for battery electrolytes when additives are used. Furthermore, potassium hydroxide reacts with many organics and with the carbon dioxide in air to form carbonates. The build-up of carbonates in the electrolyte is to be avoided because carbonates reduce electrolyte conductivity and electrode activity in some cases. 

Table 5.29 Typical reactions of persons to carbon dioxide in air...

Disappearing ink can be prepared by first dissolving solid thymolphthalein in ethanol, adding water, and then adjusting the pH with sodium hydroxide solution J2 The deep blue color of the basic form of the indicator is readily apparent. Applying the ink to paper increases its exposure to carbon dioxide in air. Two chemical... 

Typically, acid soils are titrated with a sodium or calcium hydroxide [NaOH or Ca(OH)2] solution and basic soils with hydrochloric acid (HC1), and pH changes are most commonly followed using a pH meter. Carbonates in basic soils release C02 during treatment with HC1, thus making the titration more difficult. For this reason, carbonates are often determined by other methods. It is important to keep in mind that basic solutions react with carbon dioxide in air and form insoluble carbonates. This means that either the basic titrant is standardized each day before use or the solution is protected from exposure to carbon dioxide in air. Specific descriptions of titrant preparation, primary standards, and the use of indicators and pH meters in titrations can be found in Harris [1] and in Skoog et al. [2],... 

Emanuele, G, et al. (2002), Scripps reference gas calibration standards system for carbon dioxide-in-nitrogen and carbon dioxide-in-air, revision of 1999 (La Jolla, CA Scripps Institution of Oceanography). 

Although its expense prohibits its use in many applications, the alkali fuel cell is the primary fuel cell used in the aerospace industry, because it has a very high power density (see Box 12.1). One problem is the reaction of the alkali electrolyte with the carbon dioxide in air to form potassium carbonate, which clogs the openings in the electrode gauze. 

Carbon dioxide.—The existence of carbon dioxide in air was demonstrated by J. Black7 between 1752 and 1754 ten years later by D. McBride and in 1774, by T. Bergman. H. B. de Saussure employed lime-water as a test and N. T. de Saussure, alkaline-lye. The latter process was used by A. F. de Fourcroy, F. H. A. von Humboldt, B. Lewy, E. Frankland, I. Maeagno, etc., and P. Thenard weighed the barium carbonate produced by the action of the carbon dioxide on baryta-water. 

Even a small increase in the level of carbon dioxide in air is harmful, as it results in... 

From Table 1.6, we read the value of H, for carbon dioxide at 25°C Hcc>2 = 1640 atm/mol. The mole fraction of carbon dioxide in air is about 0.000314. Therefore, the partial pressure of carbon dioxide is... 

For the rapid determination of the percentage of chlorine and carbon dioxide in air, the following method is recommended ... 

The second generation of nonporous membranes was silicon based which displayed increased CO2 permeabilities. In 1965, Bramson et al. commercialized the first nonporous membrane BO [18]. Since the diffusion coefficient of oxygen and carbon dioxide in air is about four orders of magnitude higher than in blood, the gas side mass-transfer resistance was negligible. The major resistance to respiratory gas transfer was due to the membrane and the liquid side concentration boundary layer [19]. Though nonporous membrane BOs reduced blood damage, up to 5.5 m membrane surface area was often required to ensure adequate gas transfer rates. 

Some substances, including impurities, enhance the decomposition of azides. The impurities can be present in the course of preparation of azides or formed during their storage. It is known that the presence of carbon dioxide in air may produce a decomposition of lead azide. Also water vapour in air even at rcoin temperature may accelerate (he decompr>sition. fhis problent was tackled by. Reitzner (115]. He found that the induction period was the result of the re-laction of water vapour with lead. 

Figure 46-10 Partial pressures of oxygen and carbon dioxide in air, blood, and tissue. Values shown are approximations in mm Hg and calculated assuming a 5% shunt. Heavy arrows show directions of gradients. (Modified from Tietz NW. Fundamentals of clinical chemistry, 3rd ed. Philadelpbla WB Saunders Co, 1987.)...

The electrolyte in this fuel cell is concentrated (85 wt.%) potassium hydroxide in fuel cells operated at high temperature ( 250°C) or less concentrated (35-50 wt.%) potassium hydroxide for lower temperature (<120°C) operation. The electrolyte is retained in a matrix (usually asbestos) and a wide range of electrocatalysts can be used, for example, nickel, silver, metal oxides, spinels, and noble metals. The fuel supply is limited to nonreactive constituents except for hydrogen. Carbon monoxide is a poison and the produced carbon dioxide (in the case of having carbon monoxide) will react with the potassium hydroxide to form solid potassium carbonate, thus altering the electrolyte. Even the small amount of carbon dioxide in air must be considered as a problem in the alkaline cell. 

Which of the following statements describe physical properties and which describe chemical properties (a) Iron has a tendency to rust, (b) Rainwater in industrialized regions tends to be acidic, (c) Hemoglobin molecules have a red color, (d) When a glass of water is left out in the sun, the water gradually disappears, (e) Carbon dioxide in air is converted to more complex molecules by plants during photosynthesis. 

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