Dissociation also

The hydrogen ion flux that is provided by carbonic acid dissociation also can attack calcite (CaCO ) ... 

The solid is pale blue the liquid is an intense blue at low temperatures but the colour fades and becomes greenish due to the presence of NO2 at higher temperatures. The dissociation also limits the precision with which physical properties of the compound can be determined. At 25°C the dissociative equilibrium in the gas phase is characterized by the following thermodynamic quantities ... 

The total yield of hydrogen under the conditions of these measurements was about 1.6 molecules/100 e.v. If one-half resulted from the primary dissociation also leading to acetylene ion, a yield of 0.8 acetylene ions/100 e.v. may be estimated. This value is a minimum since acetylene ion production can also be accompanied by hydrogen atom formation and is highly uncertain but consistent with the mass spectral fragmentation pattern of acetylene and W which lead to an estimate of ca. 0.94 acetylene ions/100 e.v. 

The theory of electrolytic dissociation also provided the possibility for a transparent definition of the concept of acids and bases. According to the concepts of Arrhenius, an acid is a substance which upon dissociation forms hydrogen ions, and a base is a substance that forms hydroxyl ions. Later, these concepts were extended. 

In the presence of oxygen, the situation is more complicated, as more active species can be formed, which can contribute to NO decomposition or formation in the plasma. It was found [46] that the excited states of N2 do not contribute significantly to NO evolution, but mainly influence the dissociation or quenching of 02. As the concentration of 02 increases, their contribution to 02 dissociation also increases. Only nitrogen atoms in the ground state (N(2D)) or excited state (N(4S)) may contribute directly to NO formation by reactions with molecular oxygen ... 

In careful experiments by pulse radiolysis, the maximum G value of ozone production is 13.8, of which 6.2 comes from ionization and eventual neutralization, each such sequence giving two O atoms. If the remaining yield is attributed to the dissociation of excited states, either directly or indirectly, then the total yield of excitation will be about the same as that of ionization, 3.8 in this case, because each dissociation also gives two O atoms. 

The dissociation also is rapid helow this temperature (between 450°C to 850°C), however, only in the presence of a catalyst, such as sdica, platinum sulfide or cohalt molybdate. Other sulfur species are also produced in the reaction. 

Because the fullerene hemisphere not directly involved in metal bonding is little altered by metal complexation, it is not surprising that multimetallic adducts can be formed. However, the strength of fullerene-metal bonding, the size of the addend, and the ease of dissociation also play a part in determining the likelihood of isolating such a species. 

For N9, both neutral and cationic forms have open-chain C2v structures [64]. DFT calculations have also shown that barrier of the reaction, N9- N6+ N3, is predicted to be about 32 kcal/mol, whereas the barrier of the reaction, N9+ - N7+ + N2, is 2.1 kcal/mol. This suggests that neutral N, is kinetically more stable than the N9+ cation with respect to dissociation. Also, the relative kinetic stability of N9 is completely opposite to other oddnumbered polynitrogens such as the N5 and N7 species, where ionic forms are kinetically more stable than the neutral forms. 

Compounds 460a and 460b possess cationic structures both in the solid state and in solution. The n-butyltin derivatives 460c and 460d dissociate also into ionic species in solution but are nonionic in the solid state and involve coordinating trihates, though the... 

Once the temperature is raised to T/K, then a % of the X2 (g) molecules are converted into X(g) molecules and there are two X molecules producedfor every X2 molecule dissociated also. Thus (xa/100) = 0.0 lxa molecules of X2 are converted to produce 2(xo /100) = 0.02xo ,Xmolecules. The concentration ofX2 therefore falls from the original concentration [X2, g] = x mol dm-3... 

Few mechanistic studies on ligand replacement have been reported. Nanda and Tobe many years ago studied the displacement of Cl by Y = Br-, NCS- in [Co(Cl)3 MeAs(dmap) ], and the independence of rate on the nature and concentration of Y" suggested rate-limiting dissociation. Also it appears that [CoX(solv)(As—As)2]2+ species rapidly undergo anation by X- (halide, pseudohalide). The rate is very much faster than for the corresponding amine complexes. 

Regarding hydrochloric acid, in a concentration range of 30.10 4 to 300.10 4 mol/L, equivalent conductance assumes an extremely low and constant value of 0.03 S cm2/mol, as seen in Figure 3. This behavior certainly cannot be explained on the basis of simple dissociation phenomena. Thus we have interpreted these results on the basis of theoretical work by Caruso and co-workers (31) who consider the conductometric, potentiometric, and spectrophotometric behavior of weak acids and bases in nonaqueous solvents. In these solvents a weak acid, HA, besides undergoing simple ionic dissociation, also may undergo conjugation phenomena by the H+ and A" ions which lead to the formation of ionic complex species A(HA)/ or H(HA)/. Caruso shows that the... 

Electronic absorption spectroscopy can be used to determine the general structure of porphyins and their derivatives. The oxidation and coordination state of the iron and the identity of the amino acid that ligates the heme can be examined by comparing the absorption spectrum of the protein of interest with the spectra of known heme proteins (45, 65). General characterization with electronic absorption spectroscopy indicated that NO and CO, but not O2, bind to the sGC heme moiety (66). Dynamic studies of ligand binding and dissociation also can be examined with this technique on psec-msec time scales with standard stopped-flow systems. 

In the opinion of Parmenter and Noyes, decomposition at 3130 A consists of a rapid process from an upper repulsive state of the aldehyde molecule and of a slower one from the vibrationally excited singlet state. A temperature-dependent triplet dissociation also occurs. However, quantitative results for this latter process could not be obtained in their investigations. 

With carboxylic acid eluents, the sensitivity increases as the eluent dissociation decreases, but decreased dissociation also decreases the eluting power of the eluent. There is a trade-off between sensitivity and elution power with this system. The easiest way around this problem is to increase the eluent concentration. The sensitivity will change slightly as the extent of dissociation changes, but the strength of the eluent can be greatly increased. 

Finally, we may wonder whether the concepts of thermodynamic stabilization and kinetic stabilization are related one to the other. It is well known that most free radicals are transient, which means they are not kinetically stabilized. In other words, they recombine without activation energy and, correspondingly, their dimer dissociates also without activation energy. Thus,... 

All of the reaction products can be rationalized in terms of primary cleavage to acetyl radicals and analogy to the photolysis of acetone. However, the fact that appreciable carbon monoxide was observed 113> in iodine trapping experiments, in contrast to the results with acetone, suggests that some other primary dissociation also occurs. 

---