Equilibrium, acids

Cement mortar will be attacked by waters that have an excess of free carbon dioxide compared with that of waters that are in a lime-carbonic acid equilibrium. There is a two-step mechanism with a carbonization process according to... 

The equilibrium constant Ka is called, logically enough, the acid equilibrium constant of the weak acid HB. The Ka values of some weak acids (in order of decreasing strength) are listed in Table 13.2. The weaker the acid, the smaller the value of Ka. For example, HCN (Ka = 5.8 X 10-10) is a weaker acid than HN02, for which Ka = 6.0 X 10-4. 

The concentration of H+ ion in a buffer can be calculated if you know the concentrations of the weak acid HB and its conjugate base B . These three quantities are related through the acid equilibrium constant of HB ... 

K. See Equilibrium constant Ka. See Acid equilibrium constant See Base equilibrium constant Kc. See Equilibrium constant Kf. See Formation equilibrium constant Kr See Equilibrium constant K,p. See Solubility product constant K . See Water ion product constant K-electron capture The natural radioactive process in which an inner electron (n = 1) enters the nucleus, converting a proton to a neutron, 514 Kelvin, Lord, 8... 

We can use this more general view to discuss the strengths of acids. In our generalized acid-base reaction (52), the proton transfer implies the chemical bond in HB, must be broken and the chemical bond in HB2 must be formed. If the HB, bond is easily broken, then HB, will be a strong acid. Then equilibrium will tend to favor a proton transfer from HB, to some other base, B2. If, on the other hand, the HB, bond is extremely stable, then this substance will be a weak acid. Equilibrium will tend to favor a proton transfer from some other acid, HB2, to base B, forming the stable HB, bond. 

Region C corresponds to acidity levels at which the nitrous acid equilibrium of Scheme 3-8 is almost completely on the side of the nitrosyl ion, and that of the amine on the side of the anilinium ion. 

Nowadays it is common knowledge that in all electrophilic substitutions it is the most acidic equilibrium form of the eletrophilic reagent and the most basic form of... 

Among these reactions, the first one has the largest equilibrium constant, so the acetic acid equilibrium will generate the largest changes from initial concentrations ... 

The pH of a buffer solution depends on the weak acid equilibrium constant and the concentrations of the weak acid and its conjugate base. To show this, we begin by taking the logarithm of the acid equilibrium constant ... 

The starting pH of the solution is calculated using i and the initial molarity of the diprotic acid. We use the standard approach to a weak acid equilibrium ... 

At equilibrium, the concentration of H+ will remain constant. When a strong acid (represented by H+ or HA) is introduced into solution, the concentration of H+ is increased. The buffer compensates by reacting with the excess H ions, moving the direction of the above reaction to the left. By combining with bicarbonate and carbonate ions to form the nonionic carbonic acid, equilibrium is reestablished at a pH nearly the same as that existing before. The buffer capacity in this case is determined by the total concentration of carbonate and bicarbonate ions. When no more carbonate or bicarbonate ions are available to combine with excess H+ ions, the buffer capacity has been exceeded and pH will change dramatically upon addition of further acid. 

Table 10.23 Typical formulations of lower-strength peracetic acid equilibrium mixtures...

Strong base anion exchangers, 74 395, 411 Strong inversion, in silicon-based semiconductors, 22 239 Strong nitric acid process, materials of construction for, 77 187-188 Strong phosphoric acids, equilibrium composition of, 78 827t Strontianite, 23 317, 321 Strontium (Sr) 23 316-325 chemical properties of, 23 318 economic aspects of, 23 320-321 effect of micro additions on silicon particles in Al-Si alloys, 2 311-312 in ferrites, 77 59... 

Very feebly basic amines cannot usually be diazotised in dilute acid media and in these instances the reaction has to be carried out in a concentrated acid, normally sulphuric acid. The usual technique is first to dissolve dry sodium nitrite in the concentrated acid, when reaction occurs in two stages (Scheme 4-8), resulting in the formation of nitrosylsulphuric acid (4.5). The nitrosyl ion - nitrous acid equilibrium has been evaluated spectroscopically. In 96% sulphuric acid the 15N-n.m.r. signal is characteristic of the free nitrosyl ion [4]. Reaction (2) of Scheme 4.8 is slow at room temperature and it is desirable to heat the mixture to 70 °C in order to attain equilibrium within a reasonable time. After cooling, the amine is added gradually and after a short time the reaction mixture is poured onto ice, giving an aqueous solution of the diazonium salt [20]. 

The carbinol equilibrium (equation 19) is comparable to the nitrous acid equilibrium (equation 18), but this correlation does not exclude the nitrosacidium intermediate because the corresponding protonated carbinol was not positively excluded in equation 19. 

Chapt. 5 is entirely devoted to the hydrolytic ring opening of lactams. The reverse reaction, namely lactam formation by cyclization-dehydration, has been seldom reported in the literature, suggesting that the reaction is, indeed, uncommon. However, it is also conceivable that lactam formation has sometimes been overlooked, and that much remains to be discovered regarding structural conditions for lactam formation, the factors that influence the lactam/amino acid equilibrium, and the role of enzymes. 

As the molality m[j+ depends on the acetic acid equilibrium, which we can indicate in a simplified notation by the equation... 

In weaidy acidic equilibrium systems of 62 and 5 -IMP (21C) or 5 -ITP (21D), two cyclic, presumably trimeric oligomers with respectively N(l) N(7),0(6) (67) and N(l) N(7), O (H2O) (68) binding patterns of adjacently placed nucleobases were present in an approximately 1 1 ratio. The phosphate coordination was absent in the case of this Ir species in the presence of purine nucleoside 5 -triphosphate (2000ICA115). 

Uioxane. 72.166, 174-176 Dipeptkles. 263 Diphenyidichlorosilane. 133 Dipole moment. 208.217 Diprotic acids, equilibrium constants and retention bctors in hetaeric chromatography. 241... 

These surface acid equilibrium constants differ from their solution counterparts in that they reflect both an intrinsic reactivity of the particular O-H bond and an electrostatic free energy of moving H+ to and from a charged surface ... 

Demougin and Bonnet reported that both these reactions occurred at the same rate in cone, acids, equilibrium being established after about fourteen days. With nitrating acids containing an exceptionally high percentage of water, i.e. 21.7% water in experiments of Miles and Milbourn [20], or 24.6% in the experiments of Berl and Hefter [27], the balance tends to establish itself very slowly, and considerably altered products are formed due to side reactions. Efforts to achieve an absolute equilibrium fail in such instances. 

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