Calcium carbonate, chemical reactions

One harmful effect of acid rain is the deterioration of structures and statues made of marble or limestone, both of which are essentially calcium carbonate. The reaction of calcium carbonate with sulfuric acid yields carbon dioxide, water, and calcium sulfate. Because calcium sulfate is marginally soluble in water, part of the object is washed away by the rain. Write a balanced chemical equation for the reaction of sulfuric acid with calcium carbonate. 

The needed amounts of lime and soda ash can be calculated from the stoichiometry of the reactions. The effluent quaUty is a function of the solubihties of calcium carbonate and magnesium hydroxide and of the quantities of softening chemicals added. The acceptable level of total hardness can be decided and usually is 70—120 mg/L (265—454 mg/gal), expressed as CaC03. The sum of the solubihties of calcium carbonate and magnesium hydroxide is ca 50—70 mg/L (190—265 mg/gal), depending upon the pH. The sum of the concentrations of the carbonic species HCO/ +, ... 

Precipitated Calcium Carbonate. Precipitated calcium carbonate can be produced by several methods but only the carbonation process is commercially used in the United States. Limestone is calcined in a kiln to obtain carbon dioxide and quicklime. The quicklime is mixed with water to produce a milk-of-lime. Dry hydrated lime can also be used as a feedstock. Carbon dioxide gas is bubbled through the milk-of-lime in a reactor known as a carbonator. Gassing continues until the calcium hydroxide has been converted to the carbonate. The end point can be monitored chemically or by pH measurements. Reaction conditions determine the type of crystal, the size of particles, and the size distribution produced. 

Sihcon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between sihcon carbide and a variety of compounds at relatively high temperatures. Sodium sihcate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal sihcide. Sihcon carbide decomposes in fused alkahes such as potassium chromate or sodium chromate and in fused borax or cryohte, and reacts with carbon dioxide, hydrogen, ak, and steam. Sihcon carbide, resistant to chlorine below 700°C, reacts to form carbon and sihcon tetrachloride at high temperature. SiC dissociates in molten kon and the sihcon reacts with oxides present in the melt, a reaction of use in the metallurgy of kon and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new sihcon nitride-bonded type exhibits improved resistance to cryohte. 

Kotaki, Y. and Tsuge, H., 1990. Reactive crystallization of calcium carbonate by gas-liquid and liquid-liquid reactions. Canadian Journal of Chemical Engineering, 68, 435 42. 

Although sodium carbonate is needed in the manufacture of glass, very little is found in nature. It is made using two very abundant chemicals, calcium carbonate (marble) and sodium chloride (salt). The process involves many steps, but the overall reaction is... 

Tropinone is another classic compound in the history of total synthesis. The celebrated plans of Willstatter and Robinson are shown in Schemes 4.20 and 4.21 and Figure 4.63 shows a synthesis map for different ways this compoimd has been made. The synthesis tree for the three-component Robinson plan is shown in Figure 4.64. Calcium carbonate and hydrochloric acid are added as inputs to complete the balanced chemical equation since these are involved in a neutralization reaction. It is clear from the results summarized in Table 4.30 that the Robinson plan is the clear front-rimner because the synthesis is achieved in a single step even though the reaction yield is modest. Any further improvements to this method would be directed to improving this parameter. 

Scratch resistance depends on the hardness of the added particles. The problem of a lack of this property can be addressed by adding chemically identical particles of different crystal modification and Mohs hardness. The preferred additives are silica, alumina, layered silicates such as kaolin, titania, barium sulfate and calcium carbonate. The latter is only suitable for the DMT process owing to side reaction caused by acidity during the terephthalic acid (TPA) route. 

Many chemical reactions in seawater do not achieve equilibrium. The most notable are ones that involve marine organisms. Since organisms require energy, they cannot survive if their constituent biochemicals are at equilibrium. Equilibrium is also not likely to be achieved if some other process is adding or removing a chemical faster than equilibrium can be reattained. For example, calcium carbonate shells should spontaneously dissolve in deep ocean water, but some sink so fest that they can reach the sediments where they eventually become buried and, hence, preserved. In other words, the equilibrium approach is most applicable to reactions that attain equilibrium fester than any other competing processes acting on the chemical of interest. 

Ground calcium carbonate, extracted from the earth, is present in practically every country in the world in varying quantities in the form of limestone, marble, dolomite or chalk. Following the extraction, GCC needs to be ground. Dry grinding, the cheaper alternative, is often limited to a minimum particle size of 2- 3 microns. Wet grinding, more expensive, is used for fine and ultra fine material or when the final product must be a slurry (paper or paint application). Precipitated calcium carbonate is produced by chemical reaction between... 

A.D. 79 and calcium carbonate, the stuff of seashells, chalk, and limestone. Adding water to these sets off a complex set of chemical reactions that convert the gritty pasty stuff into what is essentially artificial stone. The nineteenth-century rediscovery of Roman cement, the aforementioned Portland cement, is made from a combination of burned limestone, clay, and water. It is the single most heavily used human-made material on earth. 

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