Carbon dioxide aqueous equilibrium

Addition of a solute to the aqueous phase changes the D/H and 180/16Q ratios in the free water since newly formed hydration spheres selectively take hydrogen and oxygen isotopes. This in turn results in the change in the D/H and 0/" 0 ratios in the water vapor or the 0/ 0 ratio in the carbon dioxide in equilibrium with the free water, which is considered to have an energy state similar to pure water. 

Carbon Dioxide/Water Equilibrium 345 Sulfur Dioxide 348 Ammonia/Water Equilibrium 353 Nitric Acid/Water Equilibrium 355 Equilibrium of Other Important Atmospheric Gases Aqueous-Phase Reaction Rates 361 S(IV) to S(VI) Transformation and Sulfur Chemistry 363... 

Thus, solutions of carbonates are found to be basic. Aqueous solutions of carbon dioxide are, on the other hand, acidic. The reactions in this equilibrium are... 

Water often is a reagent in an aqueous equilibrium. For example, when carbon dioxide dissolves in water, it reacts with a water molecule to form carbonic acid ... 

The human body generates a steady flow of acidic by-products during its normal metabolic processes. Foremost among these is carbon dioxide, which is a major product of the reactions the body uses to produce energy (see Section 14-). An average person produces from 10 to 20 mol (440 to 880 g) of CO2 every day. Blood carries CO2 from the cells to the lungs to be exhaled. In aqueous solution, dissolved CO2 is in equilibrium with carbonic acid H2 O + CO2 H2 CO3... 

Brelland, E. and P. Englezos, "Equilibrium Hydrate Formation Data for carbon Dioxide in Aqueous Glycerol Solutions", J. Chem. Eng. Data, 41, 11-13 (1996). 

A mixture was being stirred and steam heated when power failure interrupted stirring, and heating was turned off for a hour before power was restored. When stirring was restarted, the hot contents of the pan erupted immediately. Carbon dioxide is evolved from warm aqueous solutions of the base, and absence of stirring and presence of the carbon adsorbent would lead to non-equilibrium retention of the gas, which would be released instantaneously on stirring. 

The amount of carbon dioxide in a gaseous mixture of C02 and CO can be determined by passing the gas into an aqueous solution that contains an excess of Ba(OH)2. The C02 reacts, yielding a precipitate of BaC03, but the CO does not react. This method was used to analyze the equilibrium composition of the gas obtained when 1.77 g of C02 reacted with 2.0 g of graphite in a 1.000 L container at 1100 K. The analysis yielded 3.41 g of BaC03. Use these data to calculate Kp at 1100 K for the reaction... 

When dissolved in a solvent, some solutes combine with the solvent to form solvated species. The two outstanding examples in aqueous solution are carbon dioxide to form COz(aq) (carbonic acid) and ammonia to form NH3(aq) (ammonium hydroxide). In many cases the equilibrium constant for the reaction is unknown or not known with sufficient accuracy for thermodynamic purposes. Conventions have been established for treating such systems thermodynamically. Here we discuss the carbon dioxide-water... 

A.6 Solubility of gases. The solubility of gases in aqueous media is described by an equilibrium constant known as the Henry s Law constant, fCH. The value fCH relates the amount of gas in an aqueous phase (mol dm 3) to the partial pressure of the gas (atmosphere) at a given temperature. For carbon dioxide JCH would be defined as... 

Dholabhai PD, Bishnoi PR (1994) Hydrate equilibrium conditions in aqueous-electrolyte solutions - mixtures of methane and carbon dioxide. J Chem... 

Dholabhai PD, Kalogerakis N, Bishnoi PR (1993) Equilibrium conditions for carbon dioxide hydrate formation in aqueous electroyte solutions. J Chem Eng Data 38 650-654... 

EQUILIBRIUM DISTRIBUTION OF CARBON DIOXIDE BETWEEN THE GAS PHASE AND AQUEOUS SOLUTION... 

Dissolved carbon dioxide is different from species like S03 and NH3 in aqueous solutions in that the hydration reaction is slow enough (r, /2 = 15 seconds at pH 7 and 298 K) so that the rate constants involved can be determined and can be used to calculate the hydrolysis equilibrium constant (Edsall, 1969) at 298.15 K in terms of species for... 

Experimental results are presented for high pressure phase equilibria in the binary systems carbon dioxide - acetone and carbon dioxide - ethanol and the ternary system carbon dioxide - acetone - water at 313 and 333 K and pressures between 20 and 150 bar. A high pressure optical cell with external recirculation and sampling of all phases was used for the experimental measurements. The ternary system exhibits an extensive three-phase equilibrium region with an upper and lower critical solution pressure at both temperatures. A modified cubic equation of a state with a non-quadratic mixing rule was successfully used to model the experimental data. The phase equilibrium behavior of the system is favorable for extraction of acetone from dilute aqueous solutions using supercritical carbon dioxide. 

The system carbon dioxide - acetone - water was investigated at 313 and 333 K. The system demonstrates several of the general characteristics of phase equilibrium behavior for ternary aqueous systems with a supercritical fluid. These include an extensive LLV region that appears at relatively low pressures. Carbon dioxide exhibits a high selectivity for acetone over water and can be used to extract acetone from dilute aqueous solutions. 

Table 3A.2 Experimental investigations vapor-liquid equilibrium (non-aqueous) for mixtures containing carbon dioxide and light hydrocarbons.

The distinction between physical and chemical equilibrium is important. For example, when chlorine is absorbed into water, it first enters the water as dissolved chlorine and then undergoes a relatively slow chemical reaction with water to form HOCl, H", and Cl". Two equilibrium ratios may be written—one based on total chlorine in the liquid [CI2 + HOCl + Cl"], and the other based on dissolved CI2 only. It is the latter ratio which controls the mass transfer rate. As another example, when carbon dioxide is absorbed into alkaline aqueous solutions, it first dissolves as CO2 and then reacts with OH to form bicarbonate ion. The equilibrium ratio controlling the mass transfer rate is PC02/ [CO2]. This ratio is independent of pH and is aflFected only by changes in the ionic strength of the solution. The interphase equilibria of the reaction products are important only for reversible chemical reactions. 

---