Calcium Sulfate Dihydrate → Calcium Sulfate, Hemihydrate

HRID 1098696Notes

Reaction equation

HRID 1098696 reaction equation
O.O.[S:3]([O-:7])([O-:6])(=[O:5])=[O:4].[Ca+2:8]>O>[OH2:4].[S:3]([O-:7])([O-:6])(=[O:5])=[O:4].[Ca+2:8].[Ca+2:8].[S:3]([O-:7])([O-:6])(=[O:5])=[O:4]

Participants

3

Reactant 1

HCID 24928Calcium Sulfate Dihydrate

Product 1

HCID 3033839Calcium Sulfate, Hemihydrate

Reagents, catalysts & solvents 1

HCID 962WaterSolvent5×

Procedure

The decomposition temperature of the inorganic compound hydrate is preferably from 100 to 170° C. When the decomposition temperature is less than 100° C., water due to the decomposition is produced in the early stage of the foaming and curing of the foam raw material, that is, in the stage where exothermic temperature is low. Therefore, there is a possibility that it may have an adverse influence on the foaming and curing of the raw material, or the produced water may function as a blowing agent. Calcium sulfate dihydrate (gypsum dihydrate) loses water at 128° C. to form calcium sulfate hemihydrate (gypsum hemihydrate), wherein 1.5 mol of water in 2 mol of water in the molecule decompose to form free water. Magnesium sulfate heptahydrate loses water at 150° C. to form magnesium sulfate monohydrate, wherein 6 mol of water in 7 mol of water in the molecule decompose to form free water.

Workup

  1. customis preferably from 100 to 170° C
  2. customat 128° C.

Sources & evidence

ORD record
ord-8e3ed17487d84db4a5c00985799b8e96
Source dataset
uspto-grants-2012_03
Patent number
US08143323B2

Reaction notes

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