A) \[CaS{{O}_{4}}.5{{H}_{2}}O\]
B) \[CaS{{O}_{4}}.3{{H}_{2}}O\]
C) \[CaS{{O}_{4}}.2{{H}_{2}}O\]
D) \[CaS{{O}_{4}}.1/2{{H}_{2}}O\]
Correct Answer: C
Solution :
When powdered plaster of Paris mixed with water. It takes up the water of crystallisation and forms a plastic mass that gets converted into hard solid (gypsum) within 5 to 15 min. \[CaS{{O}_{4}}.\frac{1}{2}{{H}_{2}}O\xrightarrow[{}]{{{H}_{2}}O\,(Setting)}\underset{Orthorhombic}{\mathop{CaS{{O}_{4}}.2{{H}_{2}}O}}\,\] Plaster of Paris \[\xrightarrow[{}]{Hardening}\underset{Monoclinic\text{ }(gypsum)}{\mathop{CaS{{O}_{4}}.2{{H}_{2}}O}}\,\]You need to login to perform this action.
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