Thermal decomposition of CaCO

The reaction of small amounts of SOg, carried by a nitrogen stream through an anhydrous CaCOa bed, becomes noticeable above 500 °C. A study of the formation of the stable compounds suggests the intermediate formation of CaSOa- Further reaction of CaSOa with SO2 yields CaS04 Sg. A secondary reaction of Sg on CaO (produced by thermal decomposition of CaCO ... 

Koga N, Tanaka H (1988) Kinetics of thermal-decomposition of CaCOs to MO, SrCOs to MO, BaCOs to MO. J Therm Anal 34 177-188... 

The thermal decomposition of CaCOs is probably the most intensively studied reaction of the type ... 

The thermal decomposition of CaCO indicates that the rate of reaction is dependent on how quickly heat is supplied to the system. The rate of thermal decomposition of CaCO depends on the kind of atmosphere, with a higher rate of decomposition in He, followed by Nj and Ar. This order agrees well with the order of the thermal conductivities of the gases. 

In the field of chemical kinetics the KCE was first pointed out by Zawadski and Bretsznayder [571] while studying the thermal decomposition of CaCOs under various pressure of CO2 (Ea Pco2 ) but in the field of solid state physics it was often called the thermodynamic compensation rule [569], originally derived upon conductivity studies on various oxides [575]. In the field of non-isothermal studies it was first noticed through the mathematical interplay between the kinetic parameters A and E by Sestdk [574].. Early studies pointed that non-linearity in the Arrhenius plots gives the evidence of a complex process [3, 566, 570], that the mathematical correlation of the exponential pre-factor and... 

M.l When limestone, which is principally CaCO, is heated, carbon dioxide and quicklime, CaO, are produced by the reaction CaC03(s) A > CaO(s) + C02(g). If 17.5 g of C02 is produced from the thermal decomposition of 42.73 g of CaCO , what is the percentage yield of the reaction ... 

If dolomite is the source, thermal decomposition of MgCOs at 350°C produces MgO. At this temperature, CaCOs does not decompose. The decomposition temperature for the latter is 850°C. 

The thermal decomposition of calcium propionate monohydrate has been studied and the associated enthalpy changes have been determined.It loses H2O in a single step (AH = 52.97 kJ moP ). The anhydrous salt undergoes a phase transition (AH = -3.95 kJ moP ) before it decomposes to CaCOs (AH = -791kJmoP ). 

Quicklime (CaO) is produced by the thermal decomposition of calcium carbonate (CaCOs). Calculate the volume of CO2 produced at STP from the decomposition of 152 g of CaCOs according to the reaction... 

TG curves for all the compounds exhibits one stage decomposition and a similar characterizations. The thermal decomposition of composites occurs between 403 and 500 °C. The thermal stabilities of composites increased usually with increasing CaCOs content. PC6 has the highest thermal stability among the polymer blends. It is also shown that the rate curve related to compound shifts to a higher temperature. Also, three endothermic thermal effects at different temperature in DTA profiles correspond to the melting and the decomposition of composites. In DTA curves, the first two peaks are two melting p>eaks. 

ARAGONITE (1317-65-3) CaCO, Noncombustible solid. Incompatible with acids (exothermic reaction with extensive foaming and release of gas is caused when acid is highly concentrated) acid salts alum, ammonium salts fluorine (ignition), germanium, lead diacetate, magnesium, mercurous chloride, silicon, silver nitrate, titanium. Thermal decomposition above 1517°F/825°C releases calcium oxide (quicklime) and COj. 

Thermal decomposition. Calcium carbonate decomposes into calcium oxide and carbon dioxide when heated. The heat of dissociation of CaCOs is 1781 kJ/... 

Another unusual effect associated with temperature non-uniformity in decomposing powder samples of CaCOs had been described by L vov et al. [6]. Periodic variations in the absolute decomposition rate appear during the course of decomposition (Fig. 6.4). This effect becomes more marked with an increase in the decomposition temperature and, hence, of the degree of thermal non-uniformity. The initial data for calculations of the absolute rate were obtained by Maciejewski (see [6]) for further usage in an interlaboratory study of kinetic data obtained by means of commonly accepted calculation methods [7]. These kinetic data were measured by means of a Mettler 2000C thermoanalyser during decomposition in a vacuum (5 x 10 bar) of CaCOs... 

The thermal stability of calcium carbonate (CaC03) nanoparticles on polybutadiene rubber (PBR) were studied by Shimpi and Mishra [105]. They observed that the incorporation of nano CaCOs in PBR shows better thermal stability. At 12 wt% of nano CaCOs (21, 15, and 9 nm) filled in PBR shows decomposition temperature at 491, 483, and 472 °C, respectively. At 4 wt% loading of filler, decomposition temperature is observed to be 488,480,450 °C for nano CaCOs (21, 15, and 9 nm), respectively. This enhancement in thermal stability is due to uniform dispersion of nano CaCOs throughout the matrix that keeps the rubber chains intact on cross-linking, which prevent out diffusion of the volatile decomposition product [106]. The presence of nanoinorganic particles in between the mbber chains is responsible for preventing the diffusion of the volatile decomposition products firom the mbber nanocomposites at same time. It is clear that nanoinorganic filler provides better thermal stability as compared with commercial micron size filler. 

Thus, CaCOs should be stable to thermal decomposition to CaO and CO2 at 1 atm until heated to 848°C. This is only approximate, of conrse, because you assumed that A.H° and AS° are constant with temperatnre. 

This difference can be easily explained. For formation of solid product on the reactant surface, heating of the sample in a high vacuum by radiation (for example, from the walls of an alumina container) occurs through an intermediate product layer, for example, CaO for the CaCOs decomposition. This means that the effective value of the emittance for heat transfer from the container walls to the calcite crystal covered by a CaO layer, is the product of the corresponding coefficients for the four surfaces AI2O3, CaO (outward side), CaO (inward side), and CaCOs. (The residual thermal conductivity through point contacts between CaCOs crystal and CaO nanoparticles is neglected.) If... 

Rychly, J. Vesely, K. Gal, E. Kummer, M. Jancar, J. Rychla, L. Use of thermal methods in the characterization of the high-temperature decomposition and ignition of polyolefins and EVA copolymers filled with Mg(OH)2, Al(OH)3 and CaCOs. Polym. Degrad. Stab. 1990, 30, 57-72. 

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