Calcium carbonate, decomposition

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

Calcium carbonate can be prepared by the double decomposition of calcium chloride and sodium carbonate in aqueous solution. Its density and... 

Decomposition with Bases. Alkaline decomposition of poUucite can be carried out by roasting poUucite with either a calcium carbonate—calcium chloride mix at 800—900°C or a sodium carbonate—sodium chloride mix at 600—800°C foUowed by a water leach of the roasted mass, to give an impure cesium chloride solution that is separated from the gangue by filtration (22). The solution can then be converted to cesium alum [7784-17-OJ, CS2SO4 Al2(S0 2 24H20. Extraction of cesium from the poUucite is almost complete. Solvent extraction of cesium carbonate from the cesium chloride solution using a phenol in kerosene has also been developed (23). 

Carbon dioxide and calcium carbonate The effect of carbon dioxide is closely linked with the bicarbonate content. Normal carbonates are rarely found in natural waters but sodium bicarbonate is found in some underground supplies. Calcium bicarbonate is the most important, but magnesium bicarbonate may be present in smaller quantities in general, it may be regarded as having properties similar to those of the calcium compound except that on decomposition by heat it deposits magnesium hydroxide whereas calcium bicarbonate precipitates the carbonate. 

You will notice that AS° for the decomposition of calcium carbonate is a positive quan- ... 

An example of a reaction for which AH° and AS° have the same sign is the decomposition of calcium carbonate ... 

Reacting species, predominant, 80 Reaction coordinate, 133 Reaction heat, 135 additivity of, 111 measurement of, 111 Reaction rates, 124 factors affecting, 125 Reactions, 38,129 acid-base, 188 balancing, 42, 217, 219 calcium carbonate decomposition, 143... 

Both carbonates decompose to their oxides with the evolution of carbon dioxide. The decomposition temperature for calcium carbonate is in the temperature range 650-850 °C, whilst strontium carbonate decomposes between 950 and 1150°C. Hence the amount of calcium and strontium present in a mixture may be calculated from the weight losses due to the evolution of carbon dioxide at the lower and higher temperature ranges respectively. This method could be extended to the analysis of a three-component mixture, as barium carbonate is reported to decompose at an even higher temperature ( 1300 °C) than strontium carbonate. 

As additional experiments, investigate the decomposition of calcium oxalate in a static air atmosphere and in a nitrogen atmosphere at a flow rate of 10 mL min -. Compare the final stage of the decomposition, i.e. the conversion of calcium carbonate to calcium oxide, using different furnace atmospheres. 

The most common source is the supersaturation and subsequent scaling of minerals originating in the MU water. Insoluble calcium carbonate in the form of calcite (CaC03) resulting from the thermal decomposition of soluble calcium bicarbonate [Ca(HC03)2] is a classic example. Calcium carbonate quickly forms a white, friable deposit. In addition, the hydrolysis of excess bicarbonate increases... 

The production of steel begins when iron ore is fed into a blast furnace (Fig. 16.39). The furnace, which is approximately 40 m high, is continuously replenished from the top with a mixture of ore, coke, and limestone. Each kilogram of iron produced requires about 1.75 kg of ore, 0.75 kg of coke, and 0.25 kg of limestone. The limestone, which is primarily calcium carbonate, undergoes thermal decomposition to calcium oxide (lime) and carbon dioxide. The calcium oxide, which contains the Lewis base O2", helps to remove the acidic (nonmetal oxide) and amphoteric impurities from the ore ... 

Chen, C.-T.A. (1978). Decomposition of calcium carbonate and organic carbon in the deep oceans. Science 201, 735-736. 

Consideration thus far has been on only balanced reactions which occur in one phase, that is, homogeneous reactions. There are, of course, a great many reactions which occur between substances in different phases, and these are known as heterogeneous reactions. Numerous reversible, heterogeneous reactions are known, and it is pertinent now to bestow consideration on how far the law of mass action can be applied to such cases. The familiar reaction of the decomposition of calcium carbonate thermally - a well-known example of a reversible reaction represented by the equation... 

Dissolution occurring to belong to protonation involves the processes highlighted out in Table 5.2. The dissolution of calcium carbonate in acids, the decomposition of calcium fluoride by concentrated sulfuric acid, the dissolution of ferrous sulfide in hydrochloric acid are some of the examples that can be pointed out as protonation-based dissolution. 

In a review of the course and mechanism of the catalytic decomposition of ammonium perchlorate, the considerable effects of metal oxides in reducing the explosion temperature of the salt are described [1], Solymosi s previous work had shown reductions from 440° to about 270° by dichromium trioxide, to 260° by 10 mol% of cadmium oxide and to 200°C by 0.2% of zinc oxide. The effect of various concentrations of copper chromite , copper oxide, iron oxide and potassium permanganate on the catalysed combustion of the propellant salt was studied [2], Similar studies on the effects of compounds of 11 metals and potassium dichromate in particular, have been reported [3], Presence of calcium carbonate or calcium oxide has a stabilising effect on the salt, either alone or in admixture with polystyrene [4],... 

Calcium oxide can be produced from extensive heating of limestone. Primarily composed of calcium carbonate, limestone is extracted from both underground and surface mines and heated to temperatures exceeding 180°F to convert the calcium carbonate into calcium oxide. This thermal decomposition reaction also generates carbon dioxide gas. 

Example Calculate the volume of carbon dioxide obtained, at room temperature and pressure, when 25 g of calcium carbonate undergo thermal decomposition (relative atomic masses Ca = 40, C = 12,... 

B (a) Because AngiS = +1 for the decomposition of calcium carbonate, we would predict AS >0 for the reaction, favoring the reaction at high temperatures. High temperatures also favor this endothermic (ATT > 0) reaction. 

Fig. 60. TMBA- and MS-curves of the decomposition of calcium carbonate. Heating rate...

The thermogram for calcium oxalate monohydrate (CaC204.H20) is presented in Figure 11.2. The successive plateaus correspond to the anhydrous oxalate (100-250°C), calcium carbonate (400-500°C), and finally calcium oxide (700-850°C). In other words, these plateaus on the decomposition curve designate two vital aspects, namely ... 

Stage III The decomposition of calcium carbonate to calcium oxide, which is a function of the partial pressure of the C02 in contact with the sample. The endothermal band for the carbonate decomposition is sharply peaked spread over a relatively narrower temperature range in an atmosphere of C02. 

Calcium, in oil, 27 317 Calcium carbonate, decomposition of, dislocations and, 19 377-389 Calcium molybdate, 27 206... 

If an excess of alkali be present, the soln. can be dried in vacuo at ordinary temp, without much decomposition. An excess of chlorine acting on hypochlorites at ordinary temp, liberates the acid KOCl-f Cl2-f H20==KC1+2H0C1. Similarly with bleaching powder. The liberated acid can be removed by distillation, but a rise of temp, is then attended by the formation of chloric acid. J. L. Gay Lussac (1842) dissolved two mol. of chlorine monoxide in a soln. containing a mol. of K20, and found that on evaporation in vacuo, the eq. of one mol. of chlorine monoxide was removed from the liquid this indicates that the alkali hypochlorites contain the eq. of a mol. each of chlorine monoxide, C120, andpotassium monoxide, K20. A. W. Williamson stated that hypochlorous acid does not expel carbon dioxide from the carbonates except by its own decomposition. W. Wolters, however, stated that carbon dioxide is expelled from sodium carbonate, and G. Lunge and H. Schappi drove carbon dioxide from calcium carbonate by distilling hypochlorous acid with an excess of this salt. 

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