Acidity quantitative relationships

A balanced chemical reaction indicates the quantitative relationships between the moles of reactants and products. These stoichiometric relationships provide the basis for many analytical calculations. Consider, for example, the problem of determining the amount of oxalic acid, H2C2O4, in rhubarb. One method for this analysis uses the following reaction in which we oxidize oxalic acid to CO2. 

Quantitative Calculations In acid-base titrimetry the quantitative relationship between the analyte and the titrant is determined by the stoichiometry of the relevant reactions. As outlined in Section 2C, stoichiometric calculations may be simplified by focusing on appropriate conservation principles. In an acid-base reaction the number of protons transferred between the acid and base is conserved thus... 

Gardner reported that excellent, quantitative relationships also exist between the thresholds of amino acids and peptides and the connectivity indices ( a )- These relationships are of the same order of significance as the relationship between thresholds and hydrophobicity, but they are applicable to a wider range of compounds. 

Simultaneous and continuous measurements of extracellular pH, potassium K+, and lactate in an ischemic heart were carried out to study lactic acid production, intracellular acidification, and cellular K+ loss and their quantitative relationships [6, 7], The pH sensor was fabricated on a flexible kapton substrate and the pH sensitive iridium oxide layer was electrodeposited on a planar platinum electrode. Antimony-based pH electrodes have also been used for the measurement of myocardial pH in addition to their application in esophageal acid reflux detection. 

The explosive properties of mixtures with ammonium nitrate depend on the quantitative relationship between the oxidizing agent and the explosive or combustible substance. According to Parisot and Laffitte s [9, 47] investigations the explosive properties of mixtures of aromatic nitro compounds with ammonium nitrate vary with the change in composition of the system in an almost rectilinear manner. The graph in Fig. 69 shows how the rate of detonation depends on the composition of mixtures of tetryl or picric acid with ammonium nitrate. T. Urbanski et al. [48] also obtained a rectilinear relationship for nitrostarch mixtures with ammonium or sodium nitrate (Fig. 71, p. 265). 

This equation fits the titration curve of all weak acids and enables us to deduce a number of important quantitative relationships. For example, it shows why the pKa of a weak acid is equal to the pH of the solution at the midpoint of its titration. At that point, [HA] equals [A-], and... 

Gl (MW >5000). Most of the pyrolysis fragments found in this fraction are derived from the three general classes just mentioned. Pyrrole and methylpyrrole originate from proteinaceous material such as polypeptides as well as from single amino acids such as proline and hydroxyproline. A quantitative relationship between amino acid hydrolyzable content and pyrrole abundance was established by Bracewell (20) for some Scottish brown forest soils, and such a correlation probably could be established for water. 

Amino acids in aqueous solution contain weakly acidic a-carboxyl groups and weakly basic a-amino groups. In addition, each of the acidic and basic amino acids contains an ionizable group in its side chain. Thus, both free amino acids and some amino acids combined in pep tide linkages can act as buffers. The quantitative relationship between the concentration of a weak acid (HA) and its conjugate base (A-) is described by the Henderson-Hasselbalch equation. 

The Henderson-Hasselbalch equation can be used to calculate the quantitative relationship between the concentration of a weak acid and its conjugate base. 

This quantitative relationship was observed by Dumas 7 and Soubeiran.8 With excess of oxygen the hydride explodes violently, but if the supply of oxygen is insufficient the hydrogen is first oxidised and the arsenic liberated, and this takes place also in the spontaneous oxidation of arsine by oxygen at ordinary temperatures. Exposure of the mixed gases to j3- or y-rays results in the formation of arsenious acid 9... 

Quantitative Relationships Involving Carboxylic Acids CHAPTER 20... 

Apply the Henderson-Hasselbalch equation (see "Quantitative Relationships Involving Carboxylic Acids," the box accompanying Section 19.4) to calculate the CH3NH3+/CH3NH2 ratio in water buffered at pH 7. 

Spectral information on several dealuminated zeolites (91), as well as on ZK-4 and TMA-sodalite studied by Jarman (104), who also considered the quantitative relationship between 6 and 6, is given in Table IX. The average values of 0 for hydrothermally dealuminated zeolite Y and dealuminated acid-washed mordenite, as determined by X-ray diffraction, are very close to those in nondealumina ted materials, and Thomas et al. (56) assumed that this is also true for other dealuminated zeolites. They proposed the following linear correlation between 0 and S (see Fig. 30) ... 

Yamauchi, K., Nagai, Y., and Ohashi, T. 1982. Quantitative relationship between alpha-tocopherol and polyunsaturated fatty acids and its connection to development of oxidative rancidity in chicken skeletal muscle. Agric. Biol. Chem. 46 2719-2724. 

Early attempts to use heteropoly compounds as catalysts are summarized in reviews published in 1952 (//) and 1978 (7). The first industrial process using a heteropoly catalyst was started up in 1972 for the hydration of propylene in the liquid phase. The essential role of the Keggin structure in a solid heteropoly catalyst was explicitly shown in 1975 in a patent concerning catalytic oxidation of methacrolein. Systematic research in heterogeneous catalysis with these materials started in the mid-1970s and led to the recognition of quantitative relationships between the acid or redox properties and catalytic performance... 

Calculate the percent dissociation in each of the following solutions. What is the quantitative relationship between the percent dissociation and the concentration of the acid What is the quantitative relationship between the percent dissociation and the value of Ka ... 

Advantage has been taken of the ready accessibility of eleven para-substituted trityl and 9-phenylxanthyl cations, radicals, and carbanions in a study of the quantitative relationship between their stabilities under similar conditions.2 Hammett-type correlations have also been demonstrated for each series. Heats and free energies of deprotonation and the first and second oxidation potentials of the resulting carbanions were compared. The first and second reduction potentials and the p/CR values of the cations in aqueous sulfuric acid were compared, as were calorimetric heats of hydride transfer from cyanoborohydride ion. For radicals, consistent results were obtained for bond dissociation energies derived, alternatively, from the carbocation and its reduction potential or from the carbanion and its oxidation potential. 

The first quantitative relationship for the reaction rate (by the way, also catalytic) was, apparently, first obtained by Wilhelmi in his studies of the effect of acids on cane sugar. The relationship was of the form... 

We published the Q-hypothesis in 1971 (2) and thus established for the first time a quantitative relationship between the amino acid composition of a peptide and its bitterness1 as we introduced the Tanford values and so... 

Having a conceptual understanding of the effect is a good starting point, but we still need to be able to understand the quantitative relationships between the different components in the equilibrium mixture. In this section, we will see how to deal with the common-ion effect in acid-base equilibrium problems. You will find that these problems are very similar to the weak acid problems earlier in the chapter. 

In this test, oxygen from air is used for the enzymatic oxidation of (3-D-glucose in the presence of immobilized GOD to gluconic acid and hydrogen peroxide. Hydrogen peroxide can be determined by a second enzyme reaction. With horse radish peroxidase as catalyst o-phenylendiamine is oxidized by H2O2 to 2,3-diaminophenazine, which can be photometrically determined at 490 nm, thus establishing a quantitative relationship between active GOD sites and the intensity of the absorption band. 

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