Decomposition of carbonates

Carbon monosulfide [2944-05-0] CS, is an unstable gas produced by the decomposition of carbon disulfide at low pressure ia a silent electrical discharge or photolyticaHy (1 3) ia the presence or absence of sulfur (3). It decomposes with a half-life of seconds or minutes to a black soHd of uncertain composition (1—3). The monosulfide can be stabilized ia a CS2 matrix at — 196°C, and many stable coordination complexes of CS with metals have been prepared by iadirect means (8). 

As chlorination proceeds from methyl chloride to carbon tetrachloride, the length of the C—Cl bond is decreased from 0.1786 nm in the former to 0.1755 nm in the latter (3). At ca 400°C, thermal decomposition of carbon tetrachloride occurs very slowly, whereas at 900—1300°C dissociation is extensive, forming perchloroethylene and hexachloroethane and Hberating some chlorine. Subjecting the vapor to an electric arc also forms perchloroethylene and hexachloroethane, as well as hexachlorobenzene, elementary carbon, and chlorine. 

In addition to the evolution of water, the ignition of precipitates often results in thermal decomposition reactions involving the dissociation of salts into acidic and basic components, e.g. the decomposition of carbonates and sulphates the decomposition temperatures will obviously be related to the thermal stabilities. 

The formation of a passive film of iron oxide (magnetite, Fe304), under sulfite or hydrazine reducing conditions, is optimized at pH of 11 to 12. The downside is that the decomposition of carbonates and bicarbonates produces carbon dioxide, the primary cause of condensate system corrosion. 

The corrosion risks to the steam-condensate system resulting from the decomposition of carbonates and the subsequent formation of carbonic acid. 

Much detailed information concerning the decompositions of carbonates is to be found in the review by Stem and Weise [733] and selected kinetic data are summarized in Table 14. 

The T dependence of the solubility of CsH in Cs differs significantly from those for solutions of the hydrides in the other alkali metals. Distillation leaves behind involatile impurity salts, but oxygen transport from distilland to receiver has been observed. Oxygen can be carried over with the distillate in the form of COj or CO, the former being produced by decomposition of carbonate and the latter by reduction of oxides with a carbon impurity under dry conditions near the end of distillation. The identification of CO among the noncondensable gases during the distillation of Cs lends support to this. ... 

Absolutely different situation occurs in case of polycrystalline semiconductors obtained under vacuum conditions. Thus, in paper [30] three types of ZnO samples were studied ZnO 1 obtained during heating of carbonates containing zinc in air at 600 C ZnO 2 obtained through vacuum decomposition of carbonate followed by heating at 500°C ZnO 3 powder of spectrally pure zinc oxide. 

The temperature of decomposition of carbonates of the YBCO high-temperature superconductor to oxides [97] ... 

V,/V-Disubstituted thioformamides, R1R2NCH=S, are obtained from primary or secondary amines and dimethylthioformamide at 110°C. Aromatic amines do not react for electronic reasons nor does A-methylcyclohexylamine because of steric hindrance323. Decomposition of carbon disulphide in a high-voltage discharge gives CS, which reacts... 

Holmium oxide is prepared by thermal decomposition of carbonate, oxalate, hydroxide, nitrate, sulfate, or any oxo salt of holmium ... 

Figure 14.13 shows C02 concentrations measured in ice cores at the Byrd Station in Antartica from 5000 years before the present (bp) to 40,000 years bp (Anklin et al., 1997). The use of ice core data for elucidating atmospheric composition is discussed by Delmas (1992) and in more detail in Section E.l. As seen in Fig. 14.13, atmospheric C02 concentrations about 5000 years ago were only 280 ppm. (Note that interpretation of such ice core data must be carried out with care since there is evidence that in some cases, C02 can be produced in the ice from decomposition of carbonate e.g., see Smith et al., 1997.)... 

Radushkevich LV, Lukyanovich VM (1952) About structure of carbon created at thermal decomposition of carbon monoxide on iron contact. J Phys Chem 26 88-95... 

Oxygen is evolved in nature in a remarkable manner by the decomposition of carbonic anhydride, C0 by the green leaves of plants, the vegetable assimilating the carbon, whilst the oxygen escapes into the atmosphere —... 

Many decomposition reactions produce gaseous products, such as in the decomposition of carbonic acid into water and carbon dioxide ... 

Vapor binding, or air lock, is another common cause of household radiator malfunction. Often, the vapor accumulating in the radiator is CO,2, rather than air. The C02 originates from the thermal decomposition of carbonates in the boiler. Regardless, air and C02 form a noncondensable vapor in the radiator. These noncondensables mix with the steam in the radiator. The noncondensables then reduce the concentration of the steam, by dilution. The diluted steam has a lower partial pressure than pure steam. The lower the partial pressure of the steam, the more difficult it is to condense. As the rate of condensation of the steam drops, so does the heat radiated by the radiator. 

Some reactions are brought about by the action of heat alone, for example the thermal decomposition of carbonates, and baking bread and other materials. These constitute a special class of solid reactions somewhat akin to the progressive conversion type of reaction models but with the rate limited by the rate of heat penetration from the exterior. 

NCN3 (c). Darzen1 measured the heat of decomposition of carbon perazuride. 

Most gases do not affect refractory bricks. Under high pressure hydrogen gas can reduce silicon dioxide. At appr. 400-800 °C, carbon monoxide is converted into carbon and carbon dioxide. The carbon is deposited on the brick and this may lead to brick s compression. However, a solution has been found. The decomposition of carbon monoxide appeared to be stimulated by certain iron compounds. By firing the bricks at a sufficiently high temperature, you can convert these iron compounds into iron silicates which do not act as catalysts. 

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