Dissociation, pressure thermal

Uthium Mydride. Lithium hydride [7580-67-8] is very stable thermally and melts without decomposition. In the temperature range 600—800°C, the dissociation pressure for hydrogen, Pp, in units of kPa is expressed by... 

Our group has termed this process zero pressure thermal-radiation-induced dissociation (ZTRID). 

Fi re 9. Temperature dependence of the rate of low-pressure thermal dissociation of the (H20)3CI cluster ion. (Data from Ref. 62.)... 

Figure 11. Temperature dependence of the low-pressure thermal dissociation of tetraethylsilane ion. The fitted line is the least-squares straight line, from which F, is derived. The error bar suggests the uncertainty due to data scatter. The slope (and thus FJ is estimated to be uncertain to 10%.

Low-pressure thermal dissociation, ZTRID, is only at the threshold of application to bond strength problems. It is inherently best suited to weakly bonded systems. Room temperature studies are appropriate to bond strengths in the 0.5 to 1.0 eV region. 

LiH (g). The dissociation pressure data of Hiittig and Krajewski,1 Guntz,13 and Ephraim and Michel1 yield no reliable thermal values. Mulliken reported 2.47 volt-electrons for the energy of dissociation of gaseous normal LiH into gaseous normal Li and H atoms. 

Thermal conductivity data are even more difficult to obtain. In the case of calorimetric data of heat capacity and heats of dissociation, the measurements though still reasonably challenging are aided by significant improvements in commercial calorimeters that can operate at high pressures. Thermal property data are presented in Section 6.3.2. 

The fluorine dissociation pressure over thermally unstable fluorides increases exponentially with temperature. Accordingly, even in a rather narrow temperature... 

Using separate gravimetric Knudsen effusion and KMS techniques, we have obtained data for the heat of vaporization to form K2S04(g), and detailed results will appear elsewhere ( ). From thermal data, the dissociation pressure, as represented by the reaction,... 

The thorium hydrides are thermally more stable than uranium hydride, and thus the dissociation pressure of hydrogen over ThH2 is 9228.4 Pa at 1000 K. 

MgCOj decomposes at substantially lower temperatures the dissociation pressure reaches atmospheric pressure at 400—480 C. The reaction enthalpy is 121 kJ (28.9 kcal) per mole at 25 °C. MgC03 bound in dolomite decomposes at a temperature somewhat higher than pure MgC03. The dissociation pressures are plotted in Fig. 27. The decomposition of dolomite proceeds in two stages as illustrated by differential thermal analysis curves, showing two distinctly separate endothermal peaks for MgCOa and CaCOj respectively. The DTA curves for various minerals are shown in Fig. 28 (Ivanova et al., 1974). 

The dissociation pressure of solid silver chloride at 25 C is thus 4 X lO atm. if the necessary thermal data were available, it would be possible to calculate the dissociation pressure at other temperatures (cf. 33h, 33i). 

We have now to compare the value of A obtained above from purely thermal data, with what may be called the observed value of A, namely, that obtained from vapour pressure measurements The dissociation pressure p of CuS04 H20 has been determined at 78° C, and found to be 2 S mm of mercury (It is owing to this choice of temperature that it was necessary to calculate A from the thermal data also at 78° C ) Now we have to obtain the vapour pressure ir which ice would possess, if it could be obtained as such, at 78° C This is obtained accurately from Scheel s interpolation formula1 (Verh d E> physik Gesell, 8, 391, 1905)—... 

Figure 5-59. Water vapor dissociation in thermal plasma equilibrium gas composition in hot thermal discharge zone as function of its temperature at atmospheric-pressure conditions (1) O2, (2) O, (3) OH, (4) Hj, (5) HjO, (6) H.

Figure 5-72. SO2 dissociation in atmospheric-pressure thermal plasma. Energy cost required for produetion of a sulfur atom as funetion of speeifie energy input in the case of (1) absolute quenehing (2) ideal quenching.

Figure 5-74. SO2 dissociation in atmospheric-pressure thermal plasma in presence of molecular hydrogen S02 + H2. Composition of produets as function of temperature and specific energy input (1) H2, (2) SO2, (3) S2, (4) H2O, (5) H, (6) O, (7) S, (8) OH, (9) O2, (10) SO.

Figure 5-75. HBr dissociation in atmospheric-pressure thermal plasma. Composition of products (1) HBr, (2) Br, (3) Hj, (4) H.

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