Silicon thermodynamic data

The above data are correct to about 20 kJ mole but it will be seen that the general trend among these more covalent bonds does appear to be a decrease in stability from carbon to silicon, i.e. the same way as was found for more ionic bonds in the halides. Thermodynamic data for metallorganic methyl compounds used in the produchon of semiconductor systems are shown in Table 2.3. 

It should be remarked that a detailed study of the elimination of mairganese and silicon from the liquid metal shows that silicon together with some of the mairganese is hrst removed, followed by tire rest of the manganese together with some of the carbon, which is hnally removed together widr half of the sulphur contained in the original liquid. This sequence is in accord with what would be expected from thermodynamic data for the stabilities of dre oxides. 

Experimental and estimated thermodynamic data of homoleptic dialkylzinc compounds are listed in Table 3. Like many organometallic compounds, the lower dialkylzincs have a positive enthalpy of formation, and only the incorporation of silicon atoms in the /3-position imparts significant thermodynamic stability. The mean Zn-C bond rupture enthalpies, all of which are quite low, follow a similar trend as the bond lengths in these compounds. Thus, the presence of methyl substituents in the a-position weakens the zinc-carbon bonds, while silyl substituents strengthen them. 

Prom the following thermodynamic data, with the assumptions that the heat capacities of reaction are negligible and that standard conditions (other than temperature) prevail, calculate the temperatures above which (a) carbon monoxide becomes the more stable oxide of carbon, in the presence of excess C (6) carbon is thermodynamically capable of reducing chromia (Cr2Os) to chromium metal (c) carbon might, in principle, be used to reduce rutile to titanium metal and (d) silica (taken to be a-quartz) may be reduced to silicon in a blast furnace. 

Stone and coworkers determined the /3-silicon effect in w-alkyl- and aryl-substituted carbenium ions20 and vinyl cations21 by measuring in a high-pressure mass spectrometer the thermodynamic data for the association of various alkenes and alkynes with trimethylsilylium ion. From their measured thermodynamic data they calculated, by using equations 13 and 14, the /S-silyl stabilization energies listed in Table 1. 

The thermochemistry of silicon-containing anions has very recently been compiled in an excellent review by Damrauer and Hankin4, as well as in an earlier work by Damrauer3. In these reviews the authors give a detailed introduction into the experimental techniques as well as the cycles used to obtain thermodynamic data from negative-ion gas-phase chemistry. We will therefore confine ourselves here to the discussion of a few exemplary cases, and for a more detailed overview the reader is referred to the above-mentioned publications and the literature cited therein. 

Metal-silicon bond disruption enthalpies have been measured for a series of metallocene complexes including Gp3USi(SiMe3)3. This complex was synthesized by reaction of Cp3UCl with LiSi(SiMe3)3(THF)3 in diethyl ether. The thermodynamic data were obtained by titration calorimetry with I2 (Scheme 29).80... 

The knowledge of bond strengths is central to chemistry. Unfortunately, thermodynamic data for silicon molecules are limited and only a few Si-X bond energies are known, most of them for substituted compounds where the analysis is complicated by the additional substitution. In such a situation theory is extremely valuable, being able to provide with reasonable reliability data not otherwise available. Even if the accuracy of the calculated bond energies is not very good, the trends which are observed are most probably real and useful. 

Experimental thermodynamic data for ternary Cr-Fe-Si alloys are limited. [1968Che] report the activity of silicon in Cr-Fe-Si melts along sections with 12, 18 and 25 % Cr at 1600°C. It was shown that the activity exhibits a negative deviation from ideal behavior. The dependence of logioTsi on chromium concentration is linear, and extrapolation of the relationship to zero chromium content yields a value of about 0.0027. 

Silicon is a less-noble material. The redox potential (2) is difficult to measure directly in aqueous solution since silicon is easy to be oxidized and cannot stay as silicon itself The value estimated from thermodynamic data (Bard et al. 1985) is as follows ... 

How about a separation based on differences in melting points Perhaps we can separate liquid silicon from solid Fe and solid Al. Again we look to the thermodynamic data. 

Silylene complexes are not only stable with donor substituents but also with simple alkyl residues at silicon. These alkyl complexes still have a sufficient thermodynamic stability, but otherwise are reactive enough to allow a rich and diverse chemistry. Particularly the chlorocompounds 7 and 11 are valuable starting materials for further functionalization reactions the details of these reactions will be discussed in the forthcoming sections. The data for the known compounds are summarized in Table 1. 

This calculation enables one to program easily the stoichiometric concentration, using a small calculator. If the molecule contains other atoms, silicon, tin, manganese, lead, etc, the most stable oxides thermodynamically are sought perhaps by using enthalpies of formation data listed for inorganic substances in Part Two. 

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