What does 2(CaSO4).4(H2O) give upon heating? I know how to write the actual formula which is CaSO4.2(H2O) ---- CaSO4.1/2(H2O) but the part in bolds can't form naturally, so how do we write it?
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2(Ca SO4) . 4 (H2O) is hydrous calcium sulphate or Gypsum. Two Molecules of water are associated with a molecule of Calcium Sulphate in the crystal structure of Gypsum.
When Gypsum is heated beyond 100 °C, the water molecules get vaporized and escape from the gaps between molecules. So around 150°C we get Plaster of Paris or Calcium Sulphate Hemi hydrate.
correct: 2(Ca SO4) . H2O or (Ca SO4) . 1/2 (H2O) or
(Ca SO4)2 . H2O
This means that two molecules of Calcium Sulfate share one molecule of water in the gap between them. If Plaster of Paris is heated even more to very high temperatures, then the compound becomes anhydrous totally.
This compound Plaster of Paris does not occur naturally, as there is humidity in the atmosphere and in soil. The moisture is absorbed and so we find Gypsum.
Ca SO4 . 2 (H2O) ==> heat ==> (Ca SO4) . 1.5 (H2O) + 0.5 H2O
This happens when Gypsum is heated. The above Gypsum with 1.5 molecules of water, will lose water on heating or gain water if moisture is there. It does not remain as it is. So it is not found in nature like that.
You can write Ca SO4 . n (H2O) , with n ranging from 0.5 to 2, the n depends on moisture and temperature.
When Gypsum is heated beyond 100 °C, the water molecules get vaporized and escape from the gaps between molecules. So around 150°C we get Plaster of Paris or Calcium Sulphate Hemi hydrate.
correct: 2(Ca SO4) . H2O or (Ca SO4) . 1/2 (H2O) or
(Ca SO4)2 . H2O
This means that two molecules of Calcium Sulfate share one molecule of water in the gap between them. If Plaster of Paris is heated even more to very high temperatures, then the compound becomes anhydrous totally.
This compound Plaster of Paris does not occur naturally, as there is humidity in the atmosphere and in soil. The moisture is absorbed and so we find Gypsum.
Ca SO4 . 2 (H2O) ==> heat ==> (Ca SO4) . 1.5 (H2O) + 0.5 H2O
This happens when Gypsum is heated. The above Gypsum with 1.5 molecules of water, will lose water on heating or gain water if moisture is there. It does not remain as it is. So it is not found in nature like that.
You can write Ca SO4 . n (H2O) , with n ranging from 0.5 to 2, the n depends on moisture and temperature.
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