Plaster of Paris reverts back to gypsum when mixed with water, forming a hard solid mass. This process involves the rehydration of calcium sulfate hemihydrate, restoring its original chemical composition.
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Plaster of Paris reverts back to gypsum when mixed with water, forming a hard solid mass. This process involves the rehydration of calcium sulfate hemihydrate, restoring its original chemical composition.
Plaster of Paris (calcium sulfate hemihydrate, CaSO₄⋅0.5H₂O) can revert back to gypsum (calcium sulfate dihydrate, CaSO₄⋅2H₂O) through a process called hydration. When Plaster of Paris is mixed with water, it undergoes a chemical reaction in which it absorbs water molecules and transforms back into gypsum:
CaSO₄⋅0.5H₂O + 1.5H₂O ⟶ CaSO₄⋅2H₂O
This process involves the reformation of the dihydrate form, and the resulting gypsum regains its original structure. This reversion is utilized in various applications, such as in construction and art, where Plaster of Paris is initially molded and then allowed to set by reverting to gypsum through hydration.