Carbon acids calculations

Quantum-chemical calculations of PES for carbonic acid dimers [Meier et al. 1982] have shown that at fixed heavy-atom coordinates the barrier is higher than 30kcal/mol, and distance between O atoms is 2.61-2.71 A. Stretching skeleton vibrations reduce this distance in the transition state to 2.45-2.35 A, when the barrier height becomes less than 3 kcal/mol. Meier et al. [1982] have stressed that the transfer is possible only due to the skeleton deformation, which shortens the distances for the hydrogen atom tunneling from 0.6-0.7 A to 0.3 A. The effective tunneling mass exceeds 2mn-... 

The smallest value of K for any acid in Table 9 is 2.36 X 10-11 for carbonic acid at 0°C. From (132) in this case we find the value J = 0.6708 electron-volt. The values of K for the self-dissociation of water, given in Table 9, are still smaller. To calculate J we use (129) instead of (91), and at 60°C obtain the value J = 1.092 electron-volts. 

The distilled water you use in the laboratory is slightly acidic because of dissolved C02, which reacts to form carbonic acid, H2CC>3. Calculate the pH of a 0.0010 M solution of H2C03. 

Dissolve 20 g of tetra-n-butylammonium iodide in 100 mL of dry methanol and pass this solution through the column at a rate of about 5 mL min - L the effluent must be collected in a vessel fitted with a Carbosorb guard tube to protect it from atmospheric carbon dioxide. Then pass 200 mL of dry methanol through the column. Standardise the methanolic solution by carrying out a potentiometric titration of an accurately weighed portion (about 0.3 g) of benzoic acid. Calculate the molarity of the solution and add sufficient dry methanol to make it approximately 0.1M. 

The relative neutralizing capacity (RNC) of amines can be calculated from the reaction mole ratios thus, from the reaction of ammonia with carbonic acid, shown here, the RNC is 17/44 = 0.386 ppm neutralizing amine required per ppm C02 ... 

Atmospheric O2 has a partial pressure of 0.20 bar, and atmospheric water vapor is saturated with carbon dioxide. This dissolved CO2 forms carbonic acid, which generates a hydronium ion concentration of about 2.0 X 10 M. The Nemst equation allows calculation of the half-cell potential for the reduction of 02(g) under these... 

NMR chemical shifts of protonated carbonic acid 109 and 110 were investigated experimentally and computationally using IGLO/II chemical shift calculations for MP2/6-31G(d) optimized geometries.140... 

The data indicate that in strong acidic solution H2C03 may be in equilibrium with protonated carbonic acid. The structures of carbamic acid and its O- and N-proto-nated forms 111 and 112 were calculated at the MP2/6-31G(d) level.140... 

The HCO amount listed in table 8.28 actually represent carbonate alkalinity, calculated neglecting CO ". The alkalinity [Aik] of a solution represents its capacity to neutralize strong acids in solution. Alkalinity can be defined as the sum of equivalents of all species whose concentrations depend on the concentration of ions in solution, minus the concentration of ions in solution. For a solution containing borates and carbonates, alkalinity can be expressed as... 

Use the equilibrium equation and data from the preceding chart to calculate the concentrations of solutes in a 1 M solution of carbonic acid. The unknown concentrations of the three species may be written... 

In milk, the critical dissociation constants are pX, for citric acid, pK for phosphoric acid and pX for carbonic acid. Bearing in mind the limitations and assumptions of the above data, the following calculations can be made for the distribution of the various ions in milk at pH 6.6. 

K. Buch measured the partial press, of ammonia and carbon dioxide in mixtures of ammonium carbonate and carbamate, and from the results calculated the cone, of the free and bound ammonia and higher carbonate, and of the carbamate and carbonic acid. The hydrolysis and equilibrium constants were then calculated. The hydrolysis constants Kx and K% and the equilibrium constant K3 of the hydrocarbonate to carbamate, were ... 

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