Chlorination energy changes

Pandey et al. have used ultrasonic velocity measurement to study compatibility of EPDM and acrylonitrile-butadiene rubber (NBR) blends at various blend ratios and in the presence of compa-tibilizers, namely chloro-sulfonated polyethylene (CSM) and chlorinated polyethylene (CM) [22]. They used an ultrasonic interferometer to measure sound velocity in solutions of the mbbers and then-blends. A plot of ultrasonic velocity versus composition of the blends is given in Eigure 11.1. Whereas the solution of the neat blends exhibits a wavy curve (with rise and fall), the curves for blends with compatibihzers (CSM and CM) are hnear. They resemble the curves for free energy change versus composition, where sinusoidal curves in the middle represent immiscibility and upper and lower curves stand for miscibihty. Similar curves are obtained for solutions containing 2 and 5 wt% of the blends. These results were confirmed by measurements with atomic force microscopy (AEM) and dynamic mechanical analysis as shown in Eigures 11.2 and 11.3. Substantial earher work on binary and ternary blends, particularly using EPDM and nitrile mbber, has been reported. 

C06-0107. Phosgene (CI2 C I O) is a highiy toxic gas that was used for chemical warfare during World War I. Use the bond energies in Table 6 2 to estimate the energy change that occurs when carbon monoxide and chlorine combine to make phosgene. C I 0(g) + Cl2(g) CI2 C I 0(g)... 

In this, to the free energy change for the reaction involving the interaction of chlorine and the metal oxide, is added the large value of the free energy of formation of carbon dioxide from its constituent elements. 

At 800 °C, the standard free energy change for the reaction is -45.60 kj. Carbon for reduction and chlorine for chlorination are provided by certain compounds like carbon tetrachloride, and these may be used. Using carbon tetrachloride, the chlorination may be conducted at a lower temperature (650-700 °C) according to the reaction ... 

It follows that titanium tetrachloride can not chlorinate silica because at all temperatures the free energy change for that reaction has a large positive value. In general, in the interaction between the oxide (MO) of one metal (M) and the chloride (M C12) of a different metal (M ) ... 

If the standard free energy change associated with the metal silicate chlorination reaction is given by AG , then... 

If AG has a value which is more negative than that of AG, then AG° becomes more negative than the standard free energy change for the metal oxide chlorination reaction (AG ). An oxide which is difficult to chlorinate in the free state may, therefore, be chlorinated more easily when compounded into a silicate. 

Therefore, all chlorine and bromine present in the compound under study should be converted to Cl- (aq) and Br- (aq) during the bomb process. The contribution of reactions 7.68-7.70 to the internal energy change of the bomb process can be taken into account, after their extent has been determined by chemical analysis of the final bomb solution. 

Initially, we will be concerned with the physical properties of alkanes and how these properties can be correlated by the important concept of homology. This will be followed by a brief survey of the occurrence and uses of hydrocarbons, with special reference to the petroleum industry. Chemical reactions of alkanes then will be discussed, with special emphasis on combustion and substitution reactions. These reactions are employed to illustrate how we can predict and use energy changes — particularly AH, the heat evolved or absorbed by a reacting system, which often can be estimated from bond energies. Then we consider some of the problems involved in predicting reaction rates in the context of a specific reaction, the chlorination of methane. The example is complex, but it has the virtue that we are able to break the overall reaction into quite simple steps. 

What about the energy change, AE, that occurs when sodium and chlorine react to yield Na+ and Cl- ions It s apparent from E and Eea values that the amount of energy released when a chlorine atom accepts an electron (Eea = —348.6 kj/mol) is insufficient to offset the amount absorbed when a sodium atom loses an electron (E = +495.8 kj/mol) ... 

The actual reaction of sodium with chlorine occurs all at once rather than in a stepwise manner, but energy calculations can be made more easily if we imagine a series of hypothetical steps for which experimentally measured energy values can be obtained. There are five contributions that must be taken into account to calculate the overall energy change during the formation of solid NaCI from solid sodium metal and gaseous chlorine molecules ... 

We saw in Section 6.6 that the reaction of solid sodium with gaseous chlorine to yield solid sodium chloride (Na+Cl-) is favorable by 411 kj/mol. Calculate the energy change for the alternative reaction that yields chlorine sodide (Cl+Na ), and then explain why sodium chloride formation is preferred. 

Energy change = D (Bonds broken) — D (Bonds formed) Use the data in Table 7.1 to calculate an energy change for the reaction of methane with chlorine. 

This diminishes the HOMO-LUMO gap from the porphyrin, to the chlorin and to the bacteriochlorin, explaining the bathochromic shift of the bands. The oxidation and reduction potentials of these species follow the energy changes of the HOMO and LUMO, respectively. Thus, again within a homologous series, the reduction potentials of the porphyria, chlorin, and bacteriochlorin remain essentially the same, whereas the oxidation potentials become increasingly more facile, with... 

Energy changes in the propagation steps during the chlorination of ethane... 

The energy changes occurring at each step are shown alongside the arrows AHg andZliT are heats of sublimation (sodium to free atoms) and dissociation (chlorine molecules to free atoms) and, with the ionisation potential and electron affinity and 4. ), refer to one mole of material. By Hess s law (p. 168) the change of H is independent of the path and the heat of formation is thus ... 

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