Bisulfate dissociation

To examine the possibility that the different kinetic behaviors for series al, a3, and a5 may be due to differences in ionic strength, the solutions of series al and a3 were replaced by solutions of slighdy different compositions in which small amounts of sodium perchlorate were included. Extreme assumptions about the way that the sodium perchlorate would affect the equilibrium quotients for the bisulfate dissociation were used to calculate the detailed compositions of the new solutions in order to maintain constant ionic strength at 1.50, constant sulfate ion concentration at 0.276Af, and hydrogen ion concentrations close to those of solutions al and a3. No matter which of the assumptions was made in computing the compositions, the kinetic behaviors observed for the new solution series were very similar to those reported herein for series al and a3. 

Interestingly the relative intensities of the 1165 to 1185 cm and 1091 cm features change with the applied potential. The 1165 to 1185 cm band is stronger than the 1091 cm at more positive applied potential, which could suggest that bisulfate can be further dissociated, since the applied potential induces a OH adsorption and therefore the acidity on the surface is changed favoring the bisulfate dissociation. 

Here the values of a are the activities of the designated ions in solution, and and are the equiHbrium constants for the dissociation reactions. is infinity because dissociation to hydrogen and bisulfate ions is essentially complete. The best value for is probably 0.0102 (17). Thus sulfuric acid contains a mixture of hydrogen, bisulfate, and sulfate ions where the ratios of these ions vary with concentration and temperature. 

To adjust the activities of sulfuric acid to the convention which assumes that the acid dissociates only partiaUy into hydrogen and bisulfate ions, the... 

Fig. 4. Migration contribution to the limiting current in acidified CuS04 solutions, expressed as the ratio of limiting current (iL) to limiting diffusion current (i ) r = h,so4/(( h,so, + cCuS(>4). "Sulfate refers to complete dissociation of HS04 ions. "bisulfate" to undissociated HS04 ions. Forced convection" refers to steady-state laminar boundary layers, as at a rotating disk or flat plate free convection refers to laminar free convection at a vertical electrode penetration to unsteady-state diffusion in a stagnant solution. [F rom Selman (S8).]...

Sulfuric acid is a strong acid in the dissociation of its first proton and has Ka2 = 1-2 X 10 2 for the dissociation of its second proton. As a diprotic acid, it forms two series of salts hydrogen sulfates (bisulfates), such as NaHS04, and sulfates, such as Na2S04. 

Sulfuric acid dissociates, giving a proton plus the bisulfate ion. 

The discussion in the previous sections concerning solvated species indicates that a complete knowledge of the chemical reactions that take place in a system is not necessary in order to apply thermodynamics to that system, provided that the assumptions made are applied consistently. The application of thermodynamics to sulfuric acid in aqueous solution affords another illustration of this fact. We choose the reference state of sulfuric acid to be the infinitely dilute solution. However, because we know that sulfuric acid is dissociated in aqueous solution, we must express the chemical potential in terms of the dissociation products rather than the component (Sect. 8.15). Either we can assume that the only solute species present are hydrogen ion and sulfate ion (we choose to designate the acid species as hydrogen rather than hydronium ion), or we can take into account the weak character of the bisulfate ion and assume that the species are hydrogen ion, bisulfate ion, and sulfate ion. With the first assumption, the effect of the weakness of the bisulfate ion is contained in the mean activity coefficient of the sulfuric acid, whereas with the second assumption, the ionization constant of the bisulfate ion is involved indirectly. 

There are four reactions that deal explicitly with the H+ ion (Table 3.3) one is the dissociation constant for water (Kw), two are the first and second dissociation constants of carbonic acid (K and K2), and the fourth deals with the dissociation of the bisulfate (HSOJ) ion (iFbisuifate)-... 

When bisulfates are dissolved in water, the solutions are somewhat acidic because of the dissociation of the HS04 ion as shown in Eq. (15.125). 

FIGURE 20.5 Illustration of the all the evaporation and condensation rate constants the are required for multi-component nucleation of sulfuric acid (H2SO4) and water (H2O) including the relevant products of sulfuric acid dissociation bisulfate (HSO ), sulfate (SO ), and hydronium (H3O+). 

Dissociation constants and reaction enthalpy data for the stable and most important metastable sulfur species are summarized in Table 12.4. The log K values in Table 12.4 indicate the pH at which the acid and conjugate base have equal concentrations. Bisulfate (HSO4) is a relatively strong acid. 

Sulfuric acid ranks first among all industrial chemicals in mass produced. The fertilizer, pigment, textile, and detergent industries are just a few that depend on it. The concentrated acid is a viscous, colorless liquid that is 98% H2SO4 by mass. It is a strong acid, but only the first proton dissociates completely. The hydrogen sulfate (or bisulfate) ion that results is a weak acid ... 

Molar ratio (MR) between sulfuric acid and sodium sulfate at constant sodium sulfate concentration. The second dissociation constant of sulfuric acid is rather low, in the range of 0.01. Consequently, in a solution containing both sulfuric acid and sodium sulfate at MR < 1, substantially all the sulfuric acid reacts with the stoichiometric amount of sodium sulfate to give sodium bisulfate (buffer action). Hence, the actual concentration of free protons (H ) is directly proportional to the actual concentration of sodium bisulfate and inversely proportional to that of the unreacted sodium. sulfate. This type of dependence indicates that the actual concentration of free protons should increase quickly when MR exceeds a certain critical value (ca. 0.5). At higher MR values the current transported by the protons becomes significant at the expense of that transported by the sodium ions, and the cathodic efficiency shows a sharp decrease. 

The lead-acid battery electrolyte (sulfuric acid) participates in the electrode reaction at both the positive and the negative plate when the battery discharges. Sulfuric acid dissolves in water (H2O) and dissociates into ions in two steps. First, sulfuric acid forms hydrogen and bisulfate ions [1]... 

These ions transport the electric charge between the electrodes. If the sulfuric acid in the electrolyte is very dilute, the bisulfate ion may dissociate further to hydrogen and sulfate (SO4") ions [2]... 

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