Calcium carbonate, analysis

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. 

The analysis can be made quantitative by writing the various equilibria and their values. The reactions can be added to obtain the net reaction that occurs when calcium carbonate is exposed to acidic water, and the equilibrium constant for the net reaction is the product of the individual. S eq values ... 

In conclusion, the paint sample was comprised of 63.3 wt% solids (polymers and fillers) and 36.7 wt% solvent. The solids were likely comprised of calcium carbonate and titanium dioxide at 12.6 and 17.7 wt%, respectively, of the total sample including solvent. The calcium carbonate and titanium dioxide were calculated based on the measured levels of calcium and titanium from the ICP analysis. Not counting the calcium and titanium levels there is 4.9 wt% of additional metals present. Based on the calcium carbonate level and titanium dioxide level along with the remaining percentage of metals present, 34.9 wt% of the total sample is accounted for. Therefore, the maximum level of alkyd in the sample is 28.4 wt%. TGA is recommended in order to quantify the level of alkyd and total level of mineral fillers in the dried paint sample. 

Table 12.6 Results of inorganic carbon analysis of calcareous soils by potentiometry compared with those for calcium oxide by X-ray fluorescence spectrometry... 

Why is a back titration useful in the analysis of an antacid tablet containing calcium carbonate as the active ingredient ... 

Reference materials that represent the primary deep-sea and coastal depositional environments and biological materials would solve many of the problems that radiochemists face in analysis of sediments from these settings. Radiochemists require reference materials comprising the primary end member sediment and biological types (calcium carbonate, opal, and red clay from the deep-sea and carbonate-rich, silicate-rich, and clay mineral-rich sediments from coastal environments and representative biological materials). Additional sediment reference material from a river delta would be valuable to test the release of radionuclides that occurs as riverine particles contact seawater. 

EmUiani C (1966) Paleotemperature analysis of Caribbean core P6304-8 and P6304-9 and a generalized temperature curve for the past 425000 years. J Geol 74 109-126 Emiich K, Ehhalt DH, Vogel JC (1970) Carbon isotope fractionation during the precipitation of calcium carbonate. Earth Planet Sci Lett 8 363-371 Engel MH, Macko SA, SUfer JA (1990) Carbon isotope composition of individual amino acids in the Murchison meteorite. Nature 348 47-49... 

As for properties of calcium phophate particles grown in the reactor, chemical and physical analysis were done to verify availability of this process. Table 2 shows results of chemical analysis, which made clear that our products contained mainly calcium phosphate and some calcium carbonate and could be used as the source of fertilizer. 

Fig. 27. Progressive dispersion of calcium carbonate in polypropylene within a co-rotating intermeshing twin-screw extruder. Filler dispersion is expressed in terms of a mean volume diameter determined by image analysis...

In the early days black ash was sent direct to the soap-makers and for a time was known as British barilla. The product deteriorated rapidly when kept, and does not now appear as an article of commerce. Black ash contains 40 to 45 per cent, of sodium carbonate 30 to 33 per cent, of calcium sulphide 2 to 6 per cent, of calcium oxide 6 to 10 per cent, of calcium carbonate. G. E. Davis 4 gives for the analysis of a sample ... 

XPS spectra obtained on the uncoated dolomite sample (Figure 2) showed the presence of carbon, oxygen, and calcium, as would be expected for a calcium carbonate material. Traces of chlorine, probably present as precipitated salts were also observed by electron microprobe analysis in previous studies 4). The high-resolution C Is spectrum, however, showed that carbon was present in at least three different chemical states (Figure 2, inset). The peak occurring at a BE of 284.3 eV is consistent with the presence of adventitious hydrocarbon... 

A convenient method of interpreting water analysis for the purpose of determining the calcium carbonate solubility equilibrium conditions is embodied in the Langelier equation. The Langelier equation can be used to... 

A pulverized rock sample believed to be pure calcium carbonate is subjected to chemical analysis and found to contain 51.3% Ca, 7.7% C, and 41.0% O by mass. Why can t this rock sample be pure CaC03 ... 

The ash of true leather tanned with tannin consists essentially of calcium carbonate with traces of iron and of phosphates. Coloured leathers may contain metals from the mordants used (tin, copper, iron, chromium, aluminium) tin may also be introduced as stannous chloride used for bleaching. Small quantities of silicates (talc, kaolin) may be employed in the treatment of the leather. Finally, other mineral matters (barium, magnesium and lead salts and sodium chloride) may have been added as filling to increase the weight. Complete quantitative analysis of the ash is rarely necessary, but determination of its calcium content is sometimes required, this being made by the ordinary methods. 

A derived expression relating to the saturation point of calcium carbonate solubility in water. Used frequently to interpret water analysis in order to determine the potential for CaCC>3 supersaturation and deposition (scaling) and also by inference, but not always correctly, the opposite nonscaling potential (corrosion risk). Although LSI is scaleless, the industry generally accepts and promotes the following ... 

Garcia Gutierrez [19] has described an azo coupling spectrophotometric method for the determination of nitrite and nitrate in soils. Nitrite is determined spectrophotometrically at 550 nm after treatment with sulfuric acid and N-1 -naphlhylclhylcnediamine to form an azo dye. In another portion of the sample, nitrate is reduced to nitrite by passing a pH 9.6 buffered solution through a cadmium reductor and proceeding as above. Soils were boiled with water and calcium carbonate, treated with freshly precipitated aluminium hydroxide and active carbon, and filtered prior to analysis by the above procedure. 

Vegetables were boiled with water and calcium carbonate, treated with freshly precipitated aluminium hydroxide, and filtered prior to analysis as above. 

Table 5.1 shows an application of XPS to the study of the promoted iron catalyst used in the Haber synthesis of ammonia. The sizes of the various electron intensity peaks allows a modest level of quantitative analysis. This catalyst is prepared by sintering an iron oxide, such as magnetite (Fe304) with small amounts of potassium nitrate, calcium carbonate, aluminium oxide and other trace elements at about 1900 K. The unreduced solid produced on cooling is a mixture of oxides. On exposure to the nitrogen-hydrogen reactant gas mixture in the Haber process, the catalyst is converted to its operative, reduced form containing metallic iron. As shown in Table 5.1, the elemental components of the catalyst exhibit surface enrichment or depletion, and the extent of this differs between unreduced and reduced forms. 

A solution of 20 g of desoxycorticosterone in 190 ml of absolute ethanol was stirred in an atmosphere of hydrogen in the presence of 1.68 g of 25% palladium on calcium carbonate catalyst. After 20 hours, approximately 1 molar equivalent of hydrogen had been absorbed and hydrogen uptake had ceased. The catalyst was removed by filtration and the filtrate evaporated in vacuo to yield 20 g of nearly pure product, MP 135°C to 140°C. The crude product was demonstrated to be free of starting material by paper chromatography. A highly purified product was obtained by recrystallization from acetone-water with cooling in an ice bath, yield 14.5 g, MP 152°C to 154°C. The product was characterized by analysis and by absence of ultraviolet absorption. 

X-ray Diffraction Analysis. The inorganic components of paper are the most suitable ones for quantitative X-ray diffraction analysis. Most of these compounds are minerals and are present as fillers, coatings and pigments (often whiteners) which are added to improve the properties of the paper. Examples of compounds commonly added to paper are alumina, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, calcium sul-foaluminate, iron oxide, magnesium silicate, silica, titanium dioxide, zinc oxide, and zinc sulfide (28). Some of these, e.g., calcium carbonate and titanium dioxide, may be present in any of... 

Fig. 13. Cluster analysis of a batch of 64 acoustic emissions obtained from a stressed sample of polypropylene + 40% calcium carbonate. Parameters maximum amplitude, variance, and median frequency. The bounds of each cluster are indicated in the mapped projection...

The compound composition of each paste was calculated from the chemical analysis in terms of oxides (CaO, Si02, Al203, MgO, B203, C02, and H20), the free calcium hydroxide, and the unhydrated material present. The amount and composition of the tobermorite present were obtained from the difference between the total analysis and the amounts of the oxides required to account for calcium hydroxide and the unhydrated material. Allowance was made for minor impurities such as calcium carbonate. 

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