Enthalpy, oxygen

Enolate The anion of an enol, in which the negative charge formally resides on the oxygen. Enthalpy The energy of a system. 

The enthalpy of decomposition has been determined to be approximately 10 kJ/mol (2.4 kcal/mol) of KMnO (105). The decomposition has been shown to occur ia two stages. In the first stage essentially all of the KMnO decomposes iato K2(Mn0 2 5-Mn02 accompanied by the release of oxygen in... 

Calculation of group increments for oxygen, sulfur and nitrogen compounds has allowed the estimation of conventional ring-strain energies (CRSE) for saturated heterocycles from enthalpies of formation. For 1,3-dioxolane, CRSE is about 20 kJ mol . In 2,4-dialkyl-l,3-dioxolanes the cis form is always thermodynamically the more stable by approximately 1 kJ mol" . 

Figure B-14. Oxygen pressure-enthalpy diagram. (From Short, Kent and Walls, Pnssurt-ttiihulp ( han. for S< lfcn tl Kiv/i-neering Substances, Gulf Publishing Company, Houston, TX, 1970.)...

Enthalpy of formation. Magnesium ribbon reacts with oxygen to give MgO, a white solid, and 601.7 kJ of heat per mole of MgO formed. Hence AW MgO(s) = -601.7 kJ/mol. 

As another example, the enthalpy of formation of water can be obtained by burning H2 in oxygen... 

It is concluded [634] that, so far, rate measurements have not been particularly successful in the elucidation of mechanisms of oxide dissociations and that the resolution of apparent outstanding difficulties requires further work. There is evidence that reactions yielding molecular oxygen only involve initial interaction of ions within the lattice of the reactant and kinetic indications are that such reactions are not readily reversed. For those reactions in which the products contain at least some atomic oxygen, magnitudes of E, estimated from the somewhat limited quantity of data available, are generally smaller than the dissociation enthalpies. Decompositions of these oxides are not, therefore, single-step processes and the mechanisms are probably more complicated than has sometimes been supposed. 

During the initial stages (when a < 0.04) of the thermal decompositions of the alkali (Na, K, Rb, Cs) perchlorates [845] (giving MC103), the rates of oxygen evolution from all four salts were approximately the same and independent of particle size and sample mass. Experimental values of E ( 190 kJ mole-1) were low compared with those found by Solymosi [846] for the overall reaction (250—290 kJ mole-1) and also lower than the standard enthalpies for anion breakdown (276—289 kJ mole-1) for... 

Enthalpy of fusion, Pu-oxygen systems 129 Enthalpy of stabilization, alkali... 

The sulfoxidation of normal Cl4-CI7 paraffins with sulfur dioxide, oxygen, and water is performed under UV radiation in parallel reactors (1 in Fig. 3). The reaction enthalpy is dissipated by cooling of the paraffin in heat exchangers. The 30- to 60-kW UV lamps are cooled by a temperature-controlled water cycle. The reaction mixture leaving the reactors separates spontaneously into two phases in 2. The lighter paraffin phase is recirculated to the reactors. The composition of the heavy raw acid phase is shown in Table 5. 

Sfi f-Test 6.13B Methanol is a clean-burning liquid fuel proposed as a replacement for gasoline. Suppose it could be produced by the controlled reaction of the oxygen in air with methane. Find the standard reaction enthalpy for the formation of I mol CHjOH(l) from methane and oxygen, given the following information ... 

The decomposition of tri- and tetrasulfane in CCI4 solution (0.2 mol 1 ) at 70 °C and in the absence of oxygen has been studied by H NMR spectroscopy [64]. Initially, tetrasulfane decomposes to a mixture of tri- and pentasul-fane but slowly and after an induction period hydrogen sulfide and disulfane are formed in addition. These results have been interpreted in terms of a radical-chain reaction. The initial step is assumed to be the homolytic cleavage of the central SS bond which has by far the lowest dissociation enthalpy of the molecule ... 

C14-0051. Table lists molar enthalpies of vaporization of several substances. Calculate the molar entropy of vaporization at its normal boiling point for each of the following (a) molecular oxygen (b) ethane (c) benzene and (d) mercury. 

GP 11] [R 5] Numerically iterated parameter values for the Langmuir-Hinshelwood kinetics were listed, including activation energy, oxygen reaction rate, and enthalpy (2.0-7.0 mmol 1 hydrogen 3.6 mmol 1 oxygen 48-70 °C) [121]. 

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