Question

A compound which is prepared from gypsum has the property of hardening when mixed with water, identifying the compound and writing the chemical equation for its preparation. For what purpose is it used in the hospitals?

Answer 1

Gypsum has a chemical formula $CaS{o_4}.2{H_2}O$ (Calcium sulfate dihydrate). It is a white powder. The word gypsum means “plaster”. Gypsum is commonly found as a deposit near lakes, hot springs, volcanoes etc.

Complete step by step answer:
Gypsum is a water soluble compound but its solubility decreases with an increase in temperature. When gypsum is heated, water vapors are lost from it and it gets converted in a compound with chemical formula $CaS{o_4}.\dfrac{1}{2}{H_2}O$, named as “plaster of Paris”.
On heating gypsum at $373k$, plaster of Paris can be made out of it as according to the equation below: -
$CaS{o_4}.2{H_2}O(gypsum){\text{ }}\xrightarrow[{373k}]{{Heat}}CaS{o_4}.\dfrac{1}{2}{H_2}O + 1\dfrac{1}{2}{H_2}O\left( {Plaster{\text{ }}of{\text{ }}Paris} \right)$
Plaster of Paris (P.O.P.) is a waterproof, white colour powder.
On heating plaster of Paris at $473k$, it further gets converted into anhydrous calcium sulfate, also known as “dead burnt plaster of Paris”.
$CaS{o_4}.\dfrac{1}{2}{H_2}O{\text{ }}\left( {Plaster{\text{ }}of{\text{ }}Paris} \right){\text{ }}\xrightarrow[{473k}]{{Heat}}{\text{ }}CaS{o_4}(dead{\text{ }}burnt{\text{ }}plaster{\text{ }}of{\text{ }}Paris){\text{ }}$
Uses of plaster of Paris in hospitals are: -
(i) In hospitals, plaster of Paris is used to put cast around a fractured bone. The cast becomes stiff and helps the bone to heal.
(ii) It is used to make moulds of teeth in dentistry.
(iii) Also, it is used during individual immobilization shell production for patients in radiotherapy.
(iv) It is also used to recreate the dead tissues to reconnect limbs of dead bodies etc.

Note:
To make plaster of Paris, an ideal ratio is $2:1$. $2$ parts of plaster of Paris and one part of water. Plaster of Paris sets to form a solid cast in only a few minutes. But, before removing the P.O.P. mold, it takes about one hour to get ready for removing. Plaster of Paris is named so because gypsum for its preparation was found near Paris in ancient times.