Calcium carbonate in water

Preparation of palladium - calcium carbonate catalyst. Prepare 60 g. of precipitated calcium carbonate by mixing hot solutions of the appropriate quantities of A.R. calcium chloride and A.R. sodium carbonate. Suspend the calcium carbonate in water and add a solution containing 1 g. of palladium chloride. Warm the suspension until all the palladium is precipitated as the hydroxide upon the calcium carbonate, i.e., until the supernatant liquid is colourless. Wash several times with... 

Calcium Carbonate Protective Scale. The LangeHer saturation index (LSI) is a useful tool for predicting the tendency of a water to deposit or dissolve calcium carbonate. Work pubHshed in 1936 deals with the conditions at which a water is in equiHbrium with calcium carbonate. An equation developed by LangeHer makes it possible to predict the tendency of calcium carbonate either to precipitate or to dissolve under varying conditions. The equation expresses the relationship of pH, calcium, total alkalinity, dissolved soHds, and temperature as they relate to the solubiHty of calcium carbonate in waters with a pH of 6.5—9.5 ... 

The action of carbonic acid on limestone produces a calcium bicarbonate solution that is exceedingly soluble in water. (For comparison, at 20°C the solubility of calcium carbonate in water is only 0.0145 g per liter while the solubility of calcium bicarbonate is 166 g per literJ ) Magnesium ions from dolomite are also released into aqueous solution according to the same mechanism. The weathering of gypsum, calcium sulfate, also releases calcium ions into natural water supplies. 

The solubility of calcium carbonate in water is approximately 15-20 ppm, dependent on temperature and other factors and is rarely present in makeup water supplies. Where it is present, there will be a phenolphthalein alkalinity (P alkalinity). 

As an example let us consider the solubility of calcium carbonate in water saturated with carbon dioxide under varying pressure (P). In the solution there is equilibrium according to the equation... 

Effect of pH on the solubility of acidic and basic substances. Solubility of calcium carbonate in water. Sulfide precipitation. Values of solubility products. 

OoiNo, T, T. Suzuki, and K. Sawada. 1987, The formation and transformation mechanism of calcium carbonate in water. Geochim. Cosmochim. Acta 51 2757-67. 

A suspension of calcium carbonate in water is to be settled in a continuous sedimentation unit. The size of the particles is reasonably uniform of 50 pm and the shape can be considered fairly spherical. The suspension has a temperature of 25°C and the specific gravity of the particles is 2.93. Calculate the concentration of the suspension if the settling velocity, determined experimentally, is 1.5 X10 m/s. 

Given the importance of non-Newtonian fluids in chemical engineering generally, it is surprising how relatively little attention the filtration of such liquids has attracted in the scientific literature. Even today, many filtration textbooks do not even mention the problem. It was not until the late 1960s that the first workable filtration equations were developed for the basic, incompressible, time-independent power-law fluids. The constant pressure and constant rate filtration relationships developed by Kozicki et alP were verified experimentally using slurries of calcium carbonate in water and dilute carboxylmethyl cellulose solutions. 

At the moment, the literature reflects contradictions about the role played by chemically reactive additives. A possible explanation is the existence of two opposite effects. First, basic compounds can catalyse ester linkage scission and thus speed up polymer degradation. On the other hand, they can neutralize carboxyl end groups and thus decrease the degradation rate. In the case of coral-PLAso blend, the poor solubility of calcium carbonate in water mini-... 

Soluble calcium salts, which can precipitate as calcium carbonate in waters containing carbon dioxide, again at cathodic areas where the high pH permits a sufficiently high concentration of carbonate ions... 

Chlorination of toluene in the complete absence of iron produces side-chain chlorination products benzyl chloride, benzal chloride, and benzotrichloride. All these compounds are valuable although the reaction is difficult to stop to produce pure intermediate products. Benzal chloride is converted to benzaldehyde with calcium carbonate in water, whereas benzotrichloride gives benzoic acid under the same conditions ... 

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