Question

A compound prepared from gypsum has the property of hardening when mixed with water (a) identify compound (b) write equation for its preparation (c) why it is used in joining fractured bone

Answer 1

(i) Plaster of pairs / Calcium sulphate hemihydrate having chemical formula CaSO4 .1/2 H2O is a form of gypsum calcium phosphate. To make casts and molds, it is mixed with water. A hard plaster made when mixed with water: a completely hydrated form of calcium sulphate.

A white powder that becomes hard solid when mixed with water, used for the production of sculptures and casts, as an additive for lime plasters and for the production of casts for broken limbs.

(ii) Its equation for preparation is CaSO4.2H20 --Heat(373K)- > CaSO4 .1/2 H2O + 1(1/2) H2O  

(iii) Used as a plaster for supporting fractured bones.. Used for making toys / statues / decorative items.-

Hope this answer is entirely satisfactory