Ionization calculation

Fluorene and 9,9-dideuteriofluorene oxidized at the same rate in DMSO and in tert-butyl alcohol solution. This observation is consistent with a rapid, reversible ionization step. In tert-butyl alcohol the exchange of alpha deuterium atoms of dideuteriofluorene was measured (see experimental section) and a second-order rate constant for ionization calculated to be 0.12 = = 0.01 mole"1 per second. Under the conditions of this experiment the rate of oxygen absorption of undeuterated fluorene was approximately 1/50 the rate of deuterium exchange from the 9,9-dideuteriofluorene. 

According to A. A. Noyes (1907), the degree of ionization decreases with a rise of temp. G. N. Lewis and G. A. Linhart have compared the degrees of ionization calculated by thermochemical data and by the ratio A/A. S. Arrhenius gives for the heat Of ionization at 35°, with W-soln., LiCl, —399 cals. NaCl, —454 cals. and KC1, —362 cals. 

The lowering of the vapour pressure of water by ammonium iodide measured by G. Tammann 9 shows that the fall is 12"5 mm. for JN-soln. 25"1 mm. for N-soln. and 243 5 for lON-soln. According to L. C. de Coppet, the soln. of a mol. of the salt in water lowers the temp, of maximum density 1T1°. The degree of ionization calculated by S. M. Johnston from the raising of the boiling point of water by normal soln. of ammonium iodide agrees with the value of N. Zelinsky and S. Krapiwin and S. Arrhenius from the electrical conductivities of soln. of a mol. of the salt in v litres of water ... 

A 0.100M solution of an acid (density = l.OlOg/mL) is 4.5% ionized. Calculate the freezing point of the solution. The molar mass of the acid is 300. 

An especially important result from these studies is that a,j is remarkably independent of the complexity of the reacting ions (in marked contrast to electron dissociative recombination), only varying over the limited range (4-10) x 10 8 cm3 s-1 at 300 K, even for ions as different as those involved in reactions (67) and (71). This coupled with the relatively weak temperature dependence of ari in practice allows a single value for ari ( 6 x 10-8 cm3 s 1) to be used for all mutual neutralization reactions in ionospheric de-ionization calculations without introducing serious errors. This value is in close accordance with estimates of ionic recombination coefficients obtained by Ulwick211 from observations of ionization production and loss rates in the atmosphere in the altitude region 50-75 km. 

In 0.0100 M solution, acetic acid is 4.2% ionized. Calculate its ionization constant. 

A 0.055 M aqueous solution of a weak, monoprotic acid is 0.85% ionized. Calculate the value of the ionization constant, K, for this acid. 

Note on atomic data for ionization calculations the vast majority of the values used for photoionization and recombination cross-sections are computed, not experimental. This does not mean that their uncertainties are zero In fact, the best values are probably not accurate to better than 15-20%. Thus, it is unreasonable to expect photoionization models to match real H II region spectra to an accuracy much better than this. 

A 0.040 M solution of a monoprotic acid is 14 percent ionized. Calculate the ionization constant of the acid. 

A 0.100 Msolution ofbromoacetic acid (BrCH2COOH) is 13.2% ionized. Calculate [H+], [BrCH2COO ], [BrCH2COOH] and K for bromoacetic acid. 

Acetic acid does not completely Ionize in solution. Percent ionization of a substance dissolved in water is equal to the moles of Ions produced as a percentage of the moles of ions that would be produced if the substance were completely ionized. Calculate the percent ionization of acetic acid in the following solutions. 

Calculations involving the ionization of polyprotic acids and bases present no great difficulties, provided that one makes a simplifying assumption, Because the second ionization constant is usually much less than the first, we can assume that the concentration of A , which is produced in the second ionization, is much less than the concentration of HA , which is produced in the first ionization. Another way of looking at it is that the first ionization accounts for most of the H+, only a little more being added by the second ionization. Calculations involving the first ionization can then be performed as if the acid were monoprotic, and the results of this calculation can then be used to find [A ]. Corresponding remarks apply to ionization of polyprotic bases. 

The pH of the acetic acid solution is higher (it is less acidic) because acetic acid only partially ionizes. Calculating the [H30 ] formed by the ionization of a weak acid requires solving an equilibrium problem similar to those in Chapter 14. Consider, for example, a 0.10 M solution of the generic weak acid HA with an acid ionization constant K. Since we can ignore the contribution of the autoionization of water, we only have to determine the concentration of H30 formed by the following equilibrium ... 

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