Acids titration data

Fish, W. and Morel, F.M.M. (1985) Propagation of error in fulvic acid titration data a comparison of three analytical methods. Can.J. Chem., 63, 1185-1193. 

If we assume as a model that cleavage of one mole of double bond leads to one mole of acid and one mole of aldehyde, we would expect to find —35 mmoles of acid in the first stage and 70 mmoles of acid at the end of aldehyde oxidation. The difference between total acid formation in the first and second stages of reaction should reflect the amount of aldehyde oxidized. The analysis of the total acid titration data indicates that only 57% (20/35 X 100% ) of the expected amount of acid is formed in the first stage. Between 33-39 mmoles of acid are formed in the second stage, which is in the range expected from oxidation of — 35 mmoles of aldehyde. 

Analysis of the total acid titration data indicates that 33-39 mmoles of acid and peracid have been formed from aldehyde oxidation. Furthermore, 34-36 mmoles of aldehyde should have been formed in the first stage and oxidized in the second stage. If aldehyde had been oxidized solely to peracid, the active oxygen determination should have showed 34-36 mmoles of peracid instead of at the most 13 mmoles (meq./2). Enough acid but not enough peracid has been formed. This means that there are at least two paths by which aldehyde can be oxidized to acid, one of which involves peracid formation. 

Hog thyroghbulin exhibits great susceptibility to denaturation at pH values below 4.8 (Heidelberger and Palmer, 1933) and the 0.42 unit shift of its isoelectric point on denaturation (Heidelberger and Pedersen, 1935) suggests that acid titration data should be obtained with a rapid-flow technique for comparison with the titration curve of the denatured protein. 

Directions are provided in this experiment for determining the dissociation constant for a weak acid. Potentiometric titration data are analyzed by a modified Gran plot. The experiment is carried out at a variety of ionic strengths and the thermodynamic dissociation constant determined by extrapolating to zero ionic strength. 

In this activity, you will first standardize a NaOH solution by using the solution to titrate a known mass of oxalic acid (H2C204). Then, you will use your standardized solution to titrate a sample of vinegar. Vinegar is a solution of acetic acid (HC2H302). From your titration data, you will be able to calculate the number of moles and the mass of the acetic acid in your vinegar sample and determine the percent of acetic acid in vinegar. 

The authors studied, as they call it, "acid-base equilibria in glacial acetic acid however, as they worked at various ratios of indicator-base concentration to HX or B concentration, we are in fact concerned with titration data. In this connection one should realize also that in solvents with low e the apparent strength of a Bronsted acid varies with the reference base used, and vice versa. Nevertheless, in HOAc the ionization constant predominates to such an extent that overall the picture of ionization vs. dissociation remains similar irrespective of the choice of reference see the data for I and B (Py) already given, and also those for HX, which the authors obtained at 25° C with I = p-naphthol-benzein (PNB) and /f B < 0.0042, i.e., for hydrochloric acid K C1 = 1.3 102, jjrfflci 3 9. IQ-6 an jjHC1 2.8 10 9 and for p-toluenesulphonic acid Kfm° = 3 7.102( K ms 4 0.10-6) Kmt = 7 3.10-9... 

Table 2 pA), values of various monobasic acids and aminium ions as determined by Hyperquad analysis of titration data at 1 x 10 3 M in anhydrous ethanol, T = 25.0 °C... 

Fitting of experimental titration data to determine the rate constants for a reversible reaction ethanol + acetic Acid <-> ethyl acetate +water ... 

In Fig. C microscopic acidity constants of the reaction AlOHg =AIOH + H+ for y-AI203 are plotted as a function of AIOH. The data are for 0.1 M NaCICV This figure illustrates (within experimental precision) the conformity of the proton titration data to the constant capacitance model. Calculate the capacitance. 

Determine the molar mass of an unknown acid using titration data. 

Perrone et al. (2001) modelled Ni(II) adsorp-tion to synthetic carbonate fluoroapatite (CaI0 ((P04)5(C03))(0H,F). The solid phase had a pHIEP of 6.3 and a ZPC of 6.4 with an SSA of 8.8m2/g, an estimated sorption site density of 3.1 sites/nm2. They conducted 8-day isotherms in closed vessels at Ni concentrations of 5 x 10-10 to 1 x 10 8 M, constant I (0.05, 0.1 or 0.5 M), constant solid phase concentrations of 10 g/dm3 at pH values of 4 to 12. As Ni sorption occurred, no significant release of Ca was seen. Sorption was reversible. Rather than precisely characterize surface functional groups, they elected to describe their sorbent surfaces using acid-base reactions for the average behaviour of all sites involved in protonation and deprotonation. Potentiametric titration data were used to estimate the constants with the FTTEQL computer code ... 

Danbrow and Rhodes used potentiometric titration data to determine the distribution of benzoic acid (HB) between water and nonionic micelles. The commercial surfactant used has the average formula C16(OC2H4)24. They obtained the following results in 4% surfactant solutions ... 

A difference plot, also called a Bjerrum plot, is an excellent means to extract metal-ligand formation constants or acid dissociation constants from titration data obtained with electrodes. We will apply the difference plot to an acid-base titration curve. 

G. Papanastasiou and I. Ziogas, Simultaneous Determination of Equivalence Volumes and Acid Dissociation Constants from Potentiometric Titration Data, Talanta 1995,42, 827. 

A. Kraft, Determination of the pAfa of Multiprotic, Weak Acids by Analyzing Potentiometric Acid-Base Titration Data with Difference Plots, ... 

The hydroxy a-amino acids l-serine and l-threonine, used as models for the 2-amino-2-deoxy glyconic acids, have been complexed with Ni(II) at 37 °C in aqueous solutions of 0.15M potassium nitrate. Values for the stability constants were obtained from iso-pH titration data which were collected by alternate, small, incremental additions of metal ion and potassium hydroxide being made such that the pH of the solution remained nearly constant. The data were consistent with the predominance of MLn species, along with additional protonated and hydrolyzed complexes. There was no evidence for the involvement of the hydroxyl group in chelation. By the same iterative computations the complexes formed between borate and mannitol have been analyzed, and the stability constants have been calculated. Complexes with mannitohborate stoichiometries of I.T, 1 2, 1 3, and 2 1 were proposed. 

The titration data were analyzed by a computer program, which was a modification of the program SCOGS (17). The systems Ni(II) and L-serine or L-threonine, as analogs of amino-sugar acids, and boric acid and mannitol-borate were evaluated. For each of these systems it was convenient to refine first the formation constants for the simple complexes, such as ML and ML2, adding other more complex species later until the best fit to the data had been obtained. 

Recent studies have shown that the NICA-Donnan model fits very well to the acid-base titration data of HAs and FAs form organic amendments and of unamended and amended soils, pointing out substantial differences in site densities,... 

From the potentiometric titration data (Si02 - H+/OH") Sidorova et al.72) calculated the value of the surface potential ip0 and the dissociation constant of the surface silicic acid Ko for the reaction ... 

Table 1 tabulates literature values for acidity constants of seven amine-Ptn complexes with notations on the temperature, ionic strength, total Ptn concentration, method employed, conditions and other remarks, and the reference number. At least six factors enter into comparing determinations of a single complex. First is the purity of the complex under investigation. Because they rely on chemical shifts of an individual species, NMR methods are less dependent on purity than potentiometric titrations, which are interpreted on the basis of equivalents of added base. Rarely is the raw titration data published, but in one case it is evident from a plot of the data that the titration curve reveals up to about 10% impurity [7], Without knowing whether the impurities are acidic, basic, inert, or even forming during... 

When ferredoxin was obtained in crystalline form, one of the basic questions was whether the unstable form of sulfur was a special constitutent of ferredoxin or whether it arose from the half-cystine residues. This question has not been answered unequivocally, but available evidence supports the presence of two types of sulfur in ferredoxin half-cystine sulfur and inorganic sulfide. This conclusion is based mainly on the specificity of the method used for determination of inorganic sulfide, on amino acid and elemental analyses, and on mercurial titration data. 

Chemistry of Polymer Oxidation. The conclusions drawn from the total acid and active oxygen titration data and the results from re-ozonization can be used to form an over-all picture of polymer oxidation. The chemistry of polymer oxidation can be represented as shown below. 

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