I Calcium carbonate

E 170 Calcium carbonates (i) Calcium carbonate (ii) Calcium hydrogen carbonate... 

Figure 17. Settling Curves Obtained With Goodhue and Smith Apparatus (I) Calcium Carbonate (2) Georgia Clay (3) Sulfur.

I. Calcium carbonate is much less expensive than strong bases. 

Shinano, H. and Sakai, M., 1969. Studies of marine microorganisms taking part in the precipitation of calcium carbonate. I. Calcium carbonate precipitation in peptone medium prepared with seawater and artificial seawater. Bull. Jpn. Soc. Sci. Fisheries, 35 1001—1969. 

Marble Dust [ECCInt I.] Calcium carbonate for putties, glazes, mild abrasive compds. 

Cupric sulfate I calcium carbonate j5,y-Ethylenenitriles from y, 7-ethylenechlorides... 

Typical materials with their associated absorption bands that may be used as internal standards in either the mull or disc technique are potassium thiocyanate 4 8/i, calcium carbonate 11 4// and potassium nitrate 12-1. ... 

Silver trifluoroacetate s. under I Calcium carbonate s. under (CH2,COO)J b... 

The alkali metals of Group I are found chiefly as the chlorides (in the earth s crust and in sea water), and also as sulphates and carbonates. Lithium occurs as the aluminatesilicate minerals, spodimene and lepidolite. Of the Group II metals (beryllium to barium) beryllium, the rarest, occurs as the aluminatesilicate, beryl-magnesium is found as the carbonate and (with calcium) as the double carbonate dolomite-, calcium, strontium and barium all occur as carbonates, calcium carbonate being very plentiful as limestone. 

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... 

A significant advantage of the PLM is in the differentiation and recognition of various forms of the same chemical substance polymorphic forms, eg, brookite, mtile, and anatase, three forms of titanium dioxide calcite, aragonite and vaterite, all forms of calcium carbonate Eorms I, II, III, and IV of HMX (a high explosive), etc. This is an important appHcation because most elements and compounds possess different crystal forms with very different physical properties. PLM is the only instmment mandated by the U.S. Environmental Protection Agency (EPA) for the detection and identification of the six forms of asbestos (qv) and other fibers in bulk samples. 

Fig. 1. Global distribution of seabed mineral deposits, where x represents chromite + barite titanium, zirconium, hafnium, and thorium tin I gold, platinum, and silver 3 sand and gravel shell, calcium carbonate gems marine polymetaUic sulfides phosphorites Cl cobalt cmsts S sulfur and B...

The largest use of calcium hypochlorite is for water treatment. It is also used for I I and household disinfectants, cleaners, and mildewcides. Most of the household uses have been limited to in-tank toilet bowl cleaners. In areas where chlorine cannot be shipped or is otherwise unavailable, calcium hypochlorite is used to bleach textiles in commercial laundries and textile mills. It is usually first converted to sodium hypochlorite by mixing it with an aqueous solution of sodium carbonate and removing the precipitated calcium carbonate. Or, it can be dissolved in the presence of sufficient sodium tripolyphosphate to prevent the precipitation of calcium salts. However, calcium hypochlorite is not usually used to bleach laundry and textiles because of problems with insoluble inorganic calcium salts and precipitation of soaps and anionic detergents as their calcium salts. 

The crude product (Note 2) is transferred to a 2-I. flask and mixed thoroughly with 200 g. of powdered calcium carbonate. About 300 cc. of water is added and the mixture is heated cautiously (Note 3) and then refluxed for fifteen hours to effect hydrolysis. The product is then distilled in a rapid current of steam (Note 4), and the distillate is collected in soo-cc. portions, cooled, and the />-bromobenzaldehyde is collected and dried in a desiccator. From the first liter of distillate 50-60 g. of -bromo-benzaldehyde melting at 55-57° is obtained. An additional... 

Bromobenzaldehyde has been prepared by the oxidation of -bromotoluene with chromyl chloride/ by saponification of the acetal from />-bromophenylmagnesium bromide and orthoformic ester/ by the oxidation of ethyl -bromobenzyl ether with nitric acid/ by the oxidation of /j-bromobenzyl bromide with lead nitrate/ and by the hydrolysis of i-bromobenzal bromide in the presence of calcium carbonate. ... 

I grain per gallon.= i grain calcium carbonate (CaCOs) per U. S. gallon of water... 

I part per million, , . = i part calcium carbonate (CaCO,) per i,000,000 parts of water... 

I English degree (or Clark). = 1 grain calcium carbonate (CaCOa) per British Imperial gal, of water... 

Although the Langelier index is probably the most frequently quoted measure of a water s corrosivity, it is at best a not very reliable guide. All that the index can do, and all that its author claimed for it is to provide an indication of a water s thermodynamic tendency to precipitate calcium carbonate. It cannot indicate if sufficient material will be deposited to completely cover all exposed metal surfaces consequently a very soft water can have a strongly positive index but still be corrosive. Similarly the index cannot take into account if the precipitate will be in the appropriate physical form, i.e. a semi-amorphous egg-shell like deposit that spreads uniformly over all the exposed surfaces rather than forming isolated crystals at a limited number of nucleation sites. The egg-shell type of deposit has been shown to be associated with the presence of organic material which affects the growth mechanism of the calcium carbonate crystals . Where a substantial and stable deposit is produced on a metal surface, this is an effective anticorrosion barrier and forms the basis of a chemical treatment to protect water pipes . However, the conditions required for such a process are not likely to arise with any natural waters. 

Five hundred grams of mesquite gum (Note i) is dissolved (Note 2) in 3 1. of cold water in a 5-1. round-bottom flask a cold solution of 125 g. of concentrated sulfuric acid in 80 cc. of water is added and the mixture warmed at 8o° for six hours (Note 3) in a large water bath. The acid is neutralized by gradual addition of 140 g. of powdered calcium carbonate (Note 4), and the solution with excess calcium carbonate is heated in a boiling water bath for an hour to complete the neutralization. The calcium sulfate is filtered off and washed with about 2 I. of hot water. The filtrate is concentrated in an evaporating dish (Note 5) on the boiling water bath to a volume of 650-700 cc. 

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. 

A 3-I. flask is provided with a mechanical stirrer, separatory funnel, thermometer, and small fractionating column leading to an efficient condenser set downward for distillation. A solution of 800 g. (4.8 moles) of tr. s. p. potassium iodide in 430 cc. of water is placed in the flask, 60 g. of calcium carbonate is added, and the mixture is heated to 60-65°, with stirring. 

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