Partial pressure of carbon dioxide

At elevated pressure, the partial pressure of carbon dioxide inhibits calcination, and siilfur dioxide is captured by displacement of the carbonate radical. The overall effect is similar except, as no free hme is formed, the resulting sorbent ash is less alkahne, consisting solely of CaS04 and CaC03. 

The oxidation rates in carbon monoxide (Fig. 5.12) are less than those for carbon dioxide. They increase steadily with temperature up to 800°C but then decrease markedly by a factor of 100 up to 1 000°C. The decrease in rate can be attributed to the beneficial factors operating at the higher temperatures with carbon dioxide and to the unfavourable thermodynamics for reaction 5.2 resulting in low equilibrium partial pressures of carbon dioxide. 

Carbon dioxide devices were originally developed by Severinghaus and Bradley (59) to measure the partial pressure of carbon dioxide in blood. This electrode, still in use today (in various automated systems for blood gas analysis), consists of an ordinary glass pH electrode covered by a carbon dioxide membrane, usually silicone, with an electrolyte (sodium bicarbonate-sodium chloride) solution entrapped between them (Figure 6-17). When carbon dioxide from the outer sample diffuses through the semipermeable membrane, it lowers the pH of the inner solution ... 

Carbon dioxide is absorbed in water from a 25 per cent mixture in nitrogen. How will its absorption rate compare with that from a mixture containing 35 per cent carbon dioxide, 40 per cent hydrogen and 25 per cent nitrogen It may be assumed that the gas-film resistance is controlling, that the partial pressure of carbon dioxide, at the gas-liquid interface is negligible and that the two-lilm theory is applicable, with the gan film thickness the same in the two cases. 

Given that the partial pressure of carbon dioxide in the troposphere is 0.26 Torr and that the temperature is 25°C, calculate the volume of air needed to produce 10.0 g of glucose. 

FIGURE 9.15 A radar imago of the surface of Venus. Although the rocks are very hot, the partial pressure of carbon dioxide in the atmosphere is so great that carbonates may be abundant. 

Thennodynamic inhibitors are complexing and chelating agents, suitable for specific scales. For example, for scale inhibition of barium sulfate, common chemicals are ethylenediaminetetraacetic acid (EDTA) andnitrilotriacetic acid. The solubility of calcium carbonate can be influenced by varying the pH or the partial pressure of carbon dioxide (CO2). The solubility increases with decreasing pH and increasing partial pressure of CO2, and it decreases with temperature. 

The system, therefore, is at equilibrium at a given temperature when the partial pressure of carbon dioxide present has the required fixed value. This result is confirmed by experiment which shows that there is a certain fixed dissociation pressure of carbon dioxide for each temperature. The same conclusion can be deduced from the application of phase rule. In this case, there are two components occurring in three phases hence F=2-3 + 2 = l, or the system has one degree of freedom. It may thus legitimately be concluded that the assumption made in applying the law of mass action to a heterogeneous system is justified, and hence that in such systems the active mass of a solid is constant. 

Paco2, partial pressure of carbon dioxide WBC, white blood cell count. 

As explained in the previous section, the P02 of the atmosphere is 160 mmHg. The partial pressure of carbon dioxide (PC02) is negligible (see Table 17.1). As air is inspired, it is warmed and humidified as it flows through the conducting airways. Therefore, water vapor is added to the gas mixture. This is accounted for in the calculation of P02 in the conducting airways ... 

Lubbers D.W., Opitz N., The pC02-/p02 optode, a new probe for measurement of partial pressure of carbon dioxide or partial pressure of oxygen in fluids and gases, Z. Naturforsch. 1975 30C 532. 

The amount of carbon dioxide in the atmosphere is proportional to the partial pressure. Thus if partial pressure is expressed in units of the present level, the amount will become 56 X 1015 pco2 moles, where pco2 is the partial pressure of carbon dioxide. Expressing the reservoir in units of 1015 moles and the exchange rate in 1015 moles/y, the equation for the time rate of change of carbon dioxide partial pressure, assuming no other sources or sinks, becomes... 

For generality, let y pco2 be the partial pressure of carbon dioxide and let x = t be the time. The equation is... 

In order to calculate the partial pressure of carbon dioxide, it is necessary to figure the total dissolved carbon and alkalinity as well. I consider three reservoirs—atmosphere, surface sea, and deep sea—as illustrated in Figure 5-1. I distinguish between the concentrations in the surface and deep reservoirs by using a terminal letter. v for the surface reservoir and d for the deep reservoir. 

Figure 6-6 also shows the variation in the partial pressure of carbon dioxide in equilibrium with the lagoon s waters. The average value of this pressure exceeds the atmospheric value, 1, so on average, carbon dioxide is evaporating from the lagoon. The evaporation rate is greatest at times of maximum alkalinity and bicarbonate concentration and minimum carbonate ion concentration. 

Figure 6-8 shows how the partial pressure of carbon dioxide in equilibrium with surface water oscillates in phase with the fluctuations in precipitation rate, saturation state, and temperature. The oscillations in alkalinity and bicarbonate concentrations have shifted in phase by about 90° because these quantities decrease when precipitation and evaporation are removing carbon from the system at above-average rates. 

Respiratory alkalosis is associated with low partial pressure of02 (25 to 35 mm Hg) and alkaline pH, but normal bicarbonate. The first two values are measured by arterial blood gas, which also yields partial pressure of carbon dioxide and arterial oxygen saturation. Circulating arterial oxygen saturation can also be measured by an oximeter, which is a noninvasive method that is fairly accurate and useful at the patient s bedside. 

FIGURE 74-1. Analysis of arterial blood gases. (HC03, bicarbonate Pco2, partial pressure of carbon dioxide.)... 

Cl ], chloride ion [HC03 ], bicarbonate [Na+], sodium ion Paco2, partial pressure of carbon dioxide from arterial blood. 

Dankwerts and McNeil ( 3) have employed the method of Van Krevelen et al. to predict the partial pressure of carbon dioxide over carbonated alkanolamine solutions. The central feature of this model is the use of pseudo-equilibrium constants and their dependence on ionic strength. The ratio of the pseudo-equilibrium constant at a certain ionic strength to that at zero ionic strength has been termed the "ionic characterization factor". However, ionic strength alone is insufficient to determine the ionic characterization factors. As well the ionic characterization factors are sometimes not a simple linear function of ionic strength. 

Other applications of the instrumentation and techniques here presented may include (i) temperature sensing employing alexandrite, ruby crystals, and Nd YAG crystals.(35 41) pH and partial pressure of carbon dioxide (pCCh) may be determined employing carboxy seminaphtorhodafluor (SNARF)-6.(42)... 

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