Calcium sulfate, anhydrous

Alternative refractive index of 1.523 for dihydrate and 1.575 for anhydrous calcium sulfate. 

Other Proeesses For Ethyl Chloride. 1,2-Dichloroethane and ethylene, after at least 3 min in the presence of anhydrous calcium sulfate at 250—350°C and pressures of 0.69—2.76 MPa (100—400 psi), yield a mixture of ethyl chloride and vinyl chloride (35). 

Estrlch, m. plaster floor layer of mortar, -gips, m. estrich gypsum, flooring plaster (a form of anhydrous calcium sulfate similar to Keene s cement), -stein, m, a kind of paving brick. 

The chloroform solution of the hydrochloride was dried over anhydrous calcium sulfate, and evaporated to dryness, leaving a semisolid residue of product ester hydrochloride. 

The precipitation of anhydrite (anhydrous calcium sulfate, CaS04) may also occur. Under ambient temperatures, anhydrite is much more soluble than calcium carbonate, but because calcium sulfate, in common with other calcium salts such as calcium phosphate (also known as tricalcium phosphate [Ca3(P04)2]), has an inverse-temperature solubility, it deposits more rapidly on the hottest heat transfer surfaces. 

Acrolein contaminated by 3% water was obtained by the submitters from Aldrich Chemical Company, Inc., and was purified by distillation from anhydrous calcium sulfate, b.p. 53°. The checkers used acrolein purchased from MC and B Manufacturing Chemists. 

Calcium sulfate, the substance used to absorb water in desiccators, provides an example of this temperature sensitivity. Anhydrous calcium sulfate absorbs water vapor from the atmosphere to give the hydrated salt. The reaction has a negative AS° because water molecules become more constrained when gaseous water molecules move into the solid state. The reaction also has a negative AH ° because of the electrical forces of attraction... 

AG jg g- - (-104.9 kJ)- (298 K) (-290.2 J/K) (10 kJ/J) - -18.4 kJ Thus, anhydrous calcium sulfate acts as a chemical sponge at room temperature, trapping water vapor spontaneously to form calcium sulfate dihydrate. 

Chlorine (BOC Gases, 99.5%) was dried with concentrated sulfuric acid and anhydrous calcium sulfate. Purging was done with 99.998% pure argon (BOC Gases). 

It is necessary that the acetylene entering the reaction flask be of high purity. The acetylene purification train illustrated in Fig. 12 consists of three 500-ml. round-bottomed traps, each containing 250 ml. of concentrated sulfuric acid, followed by a 3-ft. column containing potassium hydroxide and a drying agent such as anhydrous calcium sulfate (Drierite). Empty flasks... 

The reaction mixture is then cooled to room temperature under nitrogen. The cool mixture is steam distilled until 21. of distillate has been collected. The lower, organic layer is separated from the distillate, washed with cold water (Note 10) to remove diglyme, and dried over anhydrous calcium sulfate. Fractional distillation gives 26-31 g. (50-60%) of 2-phenylperfluoropropene, b.p. 58-59° (54 mm.), n20d 1.4225 (Notes 11 and 12). 

Use chunky dehydrating agents like anhydrous calcium sulfate (Drie-rite). Chunky drying agents have a much smaller surface area, so not much of the product gets adsorbed. 

A desiccator is a storage container used either to dry samples or, more commonly, to keep samples and crucibles dry and protected from the laboratory environment once they have been dried by other means. An indicating desiccant is a desiccant that changes color when saturated with adsorbed water. Drierite is an example of a desiccant. It is anhydrous calcium sulfate. 

Fifty-six grams (0.25 mole) of benzil monohydrazone (Org. Syn. 15, 62) (Note 1) is mixed in a mortar with 81 g. (0.38 mole) of yellow mercuric oxide and 35 g. of anhydrous calcium sulfate (Note 2). The mixture is introduced into a i-l. three-necked... 

Anhydrous calcium sulfate removes the water formed in the oxidation. 

The solution was dried over anhydrous calcium sulfate, concentrated under reduced pressure, and the polymer precipitated by methanol. The polymer was redissolved in methylene chloride, reprecipitated with methanol, and dried overnight at 100°C (0.01 mm Hg). 

Nitromethane is dried over anhydrous calcium sulfate (Drierite) or calcium chloride for 1 day and distilled the fraction with b.p. 101.5-102.5° is used. 

DRIERITE. Anhydrous calcium sulfate with a high affinity for water. 

Synonyms Anhydrous calcium sulfate anhydrous sulfate of lime gypsum (CaS04-2H20 plaster of paris (CaS04-l/2H20)... 

Synonyms anhydrous calcium sulfate-anhydrite muriacite karstenite anhydrous gypsum anhydrous sulfate of lime hemihydrate-plaster of Paris annalin dried gypsum dried calcium sulfate dihydrate-gypsum alabaster satin spar mineral white terra alha satinite light spar selenite precipitated calcium sulfate native calcium sulfate... 

Both the anhydrous calcium sulfate and dihydrate occur in nature, the former as the mineral, anhydrite, and the latter as gypsum. Gypsum is widely distributed in nature. It has been known since ancient times. 

Anhydrous calcium sulfate is a crystalline substance orthorhombic the color may vary as white, gray, blue or brick-red occurs as insoluble anhydrite or porous soluble anhydrite density 2.96 g/cm hardness 3.5 Mohs insoluble anhydrite is practically insoluble in water (0.21% at 20°C) soluble anhydrite readily absorbs moisture and is soluble in water. 

Produces an anhydrous calcium sulfate that is void of metal contamination and has a potential value as an agricultural soil amendment. 

Commercial acrolein (Shell Chemical Corp.) was distilled and shaken with an equal volume of anhydrous calcium sulfate for 30 minutes. The acrolein (containing an impurity of 3.5% of propionaldehyde) was distilled again just before use (b.p., 52.5—52.9° C.). Oxidation products identified using acrolein (99.9% purity) without propionaldehyde, which was removed by the Tischenko reaction (31). Solvents were used after purification (especially dehydration) by conventional methods. 

Filter samples for the stability and repeatability studies were prepared by spiking the filter with a known volume of the dye solution using fixed volume pipettes or volumetric syringes. The filters were then dried in a dessicator filled with anhydrous calcium sulfate and phosphorous pentoxide. The dessicator provided more rapid and uniform drying of the... 

The product is very hygroscopic and should be handled under a moisture-free environment. If the iminium salt is kept dry it has a substantial shelf life. The submitters recommend storing the product in a desiccator over anhydrous calcium sulfate. 

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