Acid dissociation constant calculations

A sample contains a weak acid analyte, HA, and a weak acid interferent, HB. The acid dissociation constants and partition coefficients for the weak acids are as follows Ra.HA = 1.0 X 10 Ra HB = 1.0 X f0 , RpjHA D,HB 500. (a) Calculate the extraction efficiency for HA and HB when 50.0 mF of sampk buffered to a pH of 7.0, is extracted with 50.0 mF of the organic solvent, (b) Which phase is enriched in the analyte (c) What are the recoveries for the analyte and interferent in this phase (d) What is the separation factor (e) A quantitative analysis is conducted on the contents of the phase enriched in analyte. What is the expected relative erroi if the selectivity coefficient, Rha.hb> is 0.500 and the initial ratio ofHB/HA was lO.O ... 

Apparent partition coefficient (logZ)) at an ionic strength of / = 0.02M, log P value of the neutral microspecies and the acidic dissociation constant of 5 was calculated (97ANC4143). The distribution coefficient of 5 was determined between 1-octanol and universal buffer in the pH range 3-10 at a... 

Using these acid dissociation constants for glycine, calculate the ratios [Z]/[C+] and [Z]/[A-] at pH... 

If the agent is an acid or a base its degree of ionization will depend on the pH. If its acid dissociation constant,is known, the degree of ionization at any pH may be calculated or determined by reference to published tables. 

Chemists have calculated the extent to which most acids and bases will dissociate in water. This mathematical value is called the acid dissociation constant (Ka) for acids and the base dissociation constant (Kb) for bases. The higher the value for Ka or Kb, the more the acid or base dissociates in water and the stronger it is. 

Table 6.5 Acidity ( dissociation ) constants Ka for inorganic Lowry-Br0nsted acids in water at 298 K. Values of Ka are dimensionless all values presuppose equilibrium constants such as Equation (6.35), and were calculated with concentrations expressed in mol dm 3...

The line-broadening data as a function of pH, typically shown for the W(IV) in Figs. 13 and 14, incorporating the known pKa values (Table II), were fitted in 5 X 5 Kubo-Sack matrices describing the exchange based on the above schemes (6, 57). The experimentally determined chemical shift and linewidth data in the absence of exchange for the aqua oxo, hydroxo oxo, and dioxo species and the pH-dependent species distribution as calculated from the acid dissociation constants for the four systems were all introduced in the different matrices and the spectra were computer simulated. For each set of chosen rate con-... 

The dioxo complexes of W(IV) and Mo(IV), having high pKa values (Table II), are formed via hydrolysis as the rate-determining step (Scheme 4) and the observed rate constants for the inversion along the O-M-O axis for the W(IV) and the Mo(IV) complexes are therefore defined by Eq. (18). These were calculated as a function of pH, using the proton exchange rate constants (Table IV) and the acid dissociation constants (Table II)... 

The value of / has been determined by NMR measurements on the mixed solvent as 0.69+0.02 and is not to be interpreted as an independent fitting parameter. With / established, can be calculated from the acid dissociation constants in pure H20 and D20, and Equation 11.68 interpreted as a zero parameter theoretical prediction of... 

You can determine the value of for a particular acid by measuring the pH of a solution. In the following investigation, you will add sodium hydroxide to acetic acid, which is a weak acid. (See Figure 8.8.) By graphing pH against the volume of sodium hydroxide that you added, you will be able to calculate the concentration of the acetic acid. Then you will be able to determine the acid dissociation constant, Ka, for this acid. 

As you know, polyprotic acids have more than one hydrogen atom that dissociates. Each dissociation has a corresponding acid dissociation constant. How can you calculate the pH of a solution of a polyprotic acid ... 

Fractionation factor acid-dissociation constants in H2O and D2O by Kreevoy (Kreevoy et al., 1977 Kresge and Chiang, 1973). This value is not as low as that for the many other systems which are known to have weaker hydrogen bonds. 

ACID DISSOCIATION CONSTANT, K CALCULATING THE pH OF A WEAK ACID... 

Similar expressions have been obtained for the particular cases of mono-protic acids and bases, diprotic acids and bases, and zwitterions (207, 208), and in each case the data conformed well to Eq. (111). It has also been shown (207) that the acid dissociation constants can be determined by using reversed phase chromatography. The pIK, values of 10 aromatic acids calculated from chromatographic data by employing Eq. (91) were... 

In the sulfite pulp process, the digestion fluid is typically made by dissolving sulfur dioxide in water in the presence of limestone until the solution contains 7.0% by weight S02, three-quarters of which is in the form of bisulfite ion. Why is this done In support of your answer to this question, calculate the pH of (a) the digestion solution prepared as above, (b) a hypothetical 7% solution of S02 alone, and (c) an actual saturated solution of S02 alone (2.9% S02), if the first acid dissociation constant of sulfurous acid is 1.7 x 10-2, at ambient temperature and pressure. 

See Eq. (4). Data from Roecker et al. (7), Gilbert et el. (9), and Pipes and Meyer (19). b Standard reduction potentials for M(III)OH2+ + e —> M(II)OH calculated from the standard reduction potentials for the aquapentakis(imine) species and the acid dissociation constants. 

The pH of 0.040 M hypobromous acid (HOBr) is 5.05. Set up the equilibrium equation for dissociation of HOBr, and calculate the value of the acid-dissociation constant. 

The isonitrile complexes of P-450 have been studied in great detail because they show two curious properties for hemo-proteins. Firstly both Fe(II) and Fe(III) complexes are formed and secondly the Fe(II) complex changes its character with pH. The Fe(II) complex at low pH has absorption maxima at 429, 530 and 557 nm, typical of other heme isonitriles, while at high pH it has absorption bands at 454, 551 and no (or very weak) absorption at 580 nm. The second spectrum is very like that of the P-450 CO complex. An acid dissociation constant for the switch between the two forms has been calculated for different isonitriles and the pKa falls as follows... 

Figure 2.3 Speciation of arsenious acid with pH. Curves calculated from acid dissociation constants listed in Table 2.10.

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