Partial dissociation

The propylene oxide complex was rather unstable and dissociated partially to its components in solution as shown by the molecular weight determined cryoseopically in benzene. This instability corresponds to the low electron donating power of the propylene oxide monomer as well as to the low electron accepting power of the catalyst. 

Dichloroiodo)arenes are yellow crystalline compounds, heat- and light-sensitive. They are stable enough to be handled without special precautions and do not hydrolyse by moisture. Several of them can be kept for long periods of time under refrigeration without any alteration, whereas others should be used as rapidly as possible after preparation. In organic solvents they dissociate partially to iodoarenes and chlorine. 

When the acid is weak (e.g., CH3COOH, HF, etc.), it only dissociates partially ... 

In ethanol acerands 4 and the reference compound 13 dissociate partially in ethanol to give pale blue solutions of phenolate anions (X max 586 nm for 13). Addition of triethylamine to the solution allows nearly complete dissociation. This blue solution was changed to violet-yellow by addition of crystalline alkali or alkaline earth metal salts. For example, a marked hypsochromic shift (A max 586-536 nm) of the longest wavelength absorption band was observed with lithium salts, LiCl and LiC104 [7]. The phenolate anion 4 (n = 2) is less susceptible than that of 4 (n = 1) for color change with metal salts. The uncrowned azophenol... 

There is another question that has to be discussed the direction of an attack in the S), 2 reaction vs. the position of the anion in the onium salts. Indeed, the simple and attractive picture proposed by Szwarc in order to explain the differences between the reactivities of maaoanions and macroion pairs in the anionic homopropagation of styrene is based on the assumption that an ion pair has to dissociate partially when the transition state of propagation is reached ). Szwarc, after observing a similar reactivity of the polystyryl anion and polystyryl cesium ion pair, also assumed that no partial dissociation was needed for the large Cs cation. The... 

The heat of formation of HgO (g) is 57.80 kcal/mole, and the heat capacity of steam is about 0.50 cal/g. What is the maximum temperature that could be expected from an oxygen-hydrogen flame One reason that this temperature is not reached in practice is that water dissociates partially to hydrogen and oxygen at very high temperatures. 

Ag(XeF2)2]AsF6 can be kept in a closed quartz vessel, but loses XeF2 slowly in a dynamic vacuum at room temperature(The dissociation partial pressure of the XeF2 from the complex must be less than that of XeF2 at 25 °C, 0.13 mmHg[ 14]). 

Certain catalysts, such as the 7r-allyl nickel halides, which are effective for butadiene, exist in dimeric form and are converted into active species by dissociation. Partial dissociation followed by addition of monomer to the active catalyst fragments would result in the rate of polymerization being proportional to [C2] [M], where C2 represents the dimeric catalyst species. 

The adduct TiMe4(THF)2 has been isolated. This compound dissociates partially in //-pentane to form TiMe4(THF). The molecular structure of the latter has been determined by X-ray diffraction and shows the titanium atom in a trigonal-bipyramidal geometry, with the THF molecule in axial position.204 The adduct TiMe4(Me2PCH2CH2PMe2) has been synthesized by addition of diphosphine to a solution TiMe4 in diethyl ether its X-ray crystal structure has been determined.205... 

The concentration dependence of viscosity of the system KF-K2NbF7 shows positive deviations from the ideal behavior, most probably due to formation of the congruently melting intermediate compound KsNbFg. This compound is, however, not stable and dissociates partially according to the reaction... 

Two main-group sandwich complexes deserve attention. Beryllium forms a complex with one tf-and one i -coordinated 1,2-azaborolyl ligand (Figure 11) <870M435>. It was shown that in solution the ionically bonded f/ -ring can dissociate partially. Thus, starting with a pure enantiomer, a racemate is formed after some time as both ring sites coordinate statistically in the ratio 1 1 (see Section 3.17.4). 

ThOj dissociates partially into ThO and O at low oxygen pressures, vapor pressure is somewhat higher. 

Table 12.5 compares four processes that have been used for concentrating The research that led to the first commercial production of was carried out by Crist and Kirshenbaum [C5] in the laboratory of H. C. Urey at Columbia University in 1943. As reported-by Kilpatrick and co-workers [Kl], it was concluded that the most satisfactory process consisted in the equilibrium distillation of the complex of boron trifluoride and dimethyl ether, BF3 (CH3)jO. When this substance vaporizes, it dissociates partially according to the reaction... 

The dimer dissociates partially and works again as template ( self-replicating ) Tjivikua et al., 1990). 

Formula weight 557.73. d 4 4.838. Lustrous, brown to black leaflets, sublimable in a Brg-Ng stream in Ng alone, dissociates partially to UBrg and Brg. Dissolves in HgO with fizzing and formation of a green liquid. 

Sometimes, an unexpectedly low result for molat mass is obtained. This happens when the molecules of the vapour on which measurements are being made dissociate, causing an increase in the actual number of particles present. If 1 mole of molecules of XY dissociate partially into X and Y, and a is the degree of dissociation, then... 

Another type of reaction which reaches an equiblmum pogtkm is thermal dissociation. For example, when phosphonisfV) chloride is heated, it dissociates partially to form phosphorus(III) chloride and chlorine ... 

Some substances (solutes) form aqueous solutions that weakly conduct electricity. Such substances are called weak electrolytes. This weak conduction of electricity is mainly because weak electrolytes only dissociate partially in solution. In other words, only a small fraction of the solute exists as ions, resulting in a solution that conducts electricity very weakly. Acetic acid (CH,COOH) and ammonia (NHj) are examples of weak electrolytes. 

But is it always necessary to complete the reaction for the propagation of combustion wave For example, in the Ti-N2 system reaction, heat is so high that the adiabatic combustion temperature reaches 3446 K, while the reaction product TiN melts completely and dissociates partially. Thermodynamic calculations show that if only one-tenth of titanium reacts with nitrogen, the temperature in the reaction zone may exceed 1300 K, and if one-fifth of titanium reacts, the temperature... 

As an example of an acid-base equilibrium problem, consider water in equilibrium with atmospheric carbon dioxide. The value of [COj (aq)] in water at 25°C in equilibrium with air that is 390 parts per million COj (close to the concentration of this gas in the atmosphere) is 1.277 X 10 mol/L. The carbon dioxide dissociates partially in water to produce equal concentrations of H+ and HCO3" ... 

The antimicrobial effect of an organic acid is not simply due to the ability to decrease pH (Abrahamsen, 1989 Adams, 1990). Weak organic acids only dissociate partially in aqueous media, and because of the lipophilic character of the undissociated form it freely penetrates the bacterial cell membrane. In the cell, the acid dissociates due to higher pH, acidifying the interior of the cell and releasing potentially toxic anions, which appear to be the most important factors in the antimicrobial activity of the organic acids. 

In the case of ionic surfactants that dissociate partially, an undissociated species u appears in the above equalities... 

Lactic acid, or CH3CHOHCOOH, dissociates partially in water to produce the lactate anion, CHjCHOHCOO", with a value of of 1.4 x lO". Calculate the pH of a 0.020 M solution of lactic acid at 25 °C. 

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