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Calcium Sulfate

plaster water paris gypsum

Calcium sulfate (CaSO4) occurs in nature in both the anhydrous and the hydrated form. The former is found primarily as the mineral known as anhydrite, while the latter is probably best known as alabaster or gypsum. Calcium sulfate also occurs in forms known as selenite, terra alba, satinite, satin spar, and light spar.

Gypsum was well known to ancient cultures. Theophrastus of Eresus (about 300 B.C.), for example, described its natural occurrence, its properties, and its uses. The Persian pharmacist Abu Mansur Muwaffaq is believed to have first described one of the major products of gypsum, plaster of Paris, around 975 A.D.

Calcium sulfate occurs as a white odorless powder or as crystals that may be tinged with color by impurities. It has a melting point of 2,642°F (1,450°C) and is only slightly soluble in water. When heated, the hydrated forms of calcium sulfate lose 1.5 molecules of water and form the hemihydrate, CaSO4 • 1/2H2O, commonly known as plaster of Paris. When added to water, plaster of Paris forms a hard mass used in making plaster casts, quick-setting cements, molds, wall plasters and wall board, and inexpensive art objects. Neither the anhydrous nor the hydrated calcium sulfate will react with water as does the hemihydrate.

Among the many other uses of calcium sulfate are as a pigment in white paints, as a soil conditioner, in Portland cement, as a sizer, filler, and coating agent in papers, in the manufacture of sulfuric acid and sulfur, in the metallurgy of zinc ores, and as a drying agent in many laboratory and commercial processes.

See also Calcium.

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over 11 years ago

Gypsum is also used as a filler in polyester resin matrix in the fibreglassing of bathtubs and spas.

When exposed to fire it releases it's latent molecules of water to extinguish the fire and is an economic solution to the STEINER TUNNEL TEST for flame spread and smoke density baseline from U.L.

In the tub and shower industry the use of gypsum has reduced emissions of styrene by some 50% depending on filler loading.

Since gypsum is PH neutral and since soil fertilizers are impaired from delivering their nutrients at high or low PH values0GYPSUM IN THE SOIL GROWS GREAT TOMATOES AND OTHER VEGGIES.

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over 8 years ago

i am looking for a complete list of products that list calcium sulfate (gypsum) as an ingredient...

please and thank you!!

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over 7 years ago

where is this compound found on the earth? Is it a natural recorce?

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about 8 years ago

Calcium sulfate is listed as ingredient in the buns of McDonald's hamburgers.

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about 7 years ago

its alllllll wrong.

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about 8 years ago

And to think this is one of the ingredients in MC DONALD'S HAMBURGER BUNS!!!

Maybe the "happy meal" isn't so happy after all! I know EVERY time I eat Mc Donald's I get sick! (And recently I ate there b/c there wasn't much else at the airport! Well, I got SICK AGAIN!)

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about 8 years ago

pls help to send to me "how to prepare calcium sulphate(plasters of paris)