Question

What is obtained when gypsum is heated at 373K?

Answer 1

Hint: As we know that gypsum is a sulfate mineral composed of calcium sulfate dihydrate and its chemical formula is $CaS{{O}_{4}}.2{{H}_{2}}O$. It is a very soft compound in nature. Here we have to tell about the compound that is obtained on heating gypsum at 373K.

Complete answer:
Let us first discuss about the gypsum mineral followed by the compound obtained from heating it at 373K as follows:-
Gypsum: It is a sulfate mineral composed of calcium sulfate dihydrate and its chemical formula is $CaS{{O}_{4}}.2{{H}_{2}}O$. It is a very soft compound in nature. It is moderately soluble in water whereas in contrast to most other salts, it exhibits retrograde solubility which means it becomes less soluble at higher temperatures.
-It occurs in nature often as flattened and twinned crystals which are transparent and cleavable masses called selenite.
-When gypsum is heated at 373K, it loses one and a half molecules of water and yields calcium sulphate hemihydrates. The reaction takes place as follows:-
$CaS{{O}_{4}}.2{{H}_{2}}O\text{ }\xrightarrow{\Delta }\text{ }CaS{{O}_{4}}.\dfrac{1}{2}{{H}_{2}}O\text{ }+\text{ }\dfrac{3}{2}{{H}_{2}}O$
-This calcium sulphate hemihydrates is famously known as ‘Plaster of Paris’. It is stored in moisture proof containers as the presence of moisture can cause the slow setting of it by bringing its hydration and this will make it useless after some time.
-From the above data, we conclude that calcium sulphate hemihydrate is obtained when gypsum is heated at 373K.

Note:
-Remember to learn and understand the concepts of chapter metallurgy.
-Plaster of Paris is especially used by doctors for supporting fractured bones and it is also used for increasing smoothness of surfaces and making toys and decorative materials.