Question

The chemical formula of diaspora, an ore of aluminum, is:
(A) $A{l_2}{O_3}.3{H_2}O$
(B) $A{l_2}{O_3}.2{H_2}O$
(C) $A{l_2}{O_3}.{H_2}O$
(D) $A{l_2}{O_3}$

Answer 1

Diaspora belongs to minerals of oxide. We can say that the crystal class of the diaspora is dipyramidal and its crystal system is orthorhombic. The elements present in the diaspora are aluminum, hydrogen, and oxygen. We can say that the color of diaspora is white, colorless, greenish gray (or) it may even exhibit color change.

Complete step by step answer:
We can otherwise call diaspora as diasporic, empholite, kayseri, or tanatarite, is an aluminum oxide hydroxide mineral, $\alpha - AlO(OH)$ , taking shape in the orthorhombic framework and isomorphous with goethite.
We have to know that diaspora appears here and there as flattened crystals, yet as a rule as lamellar or textured masses, the straightened surface being a heading of ideal cleavage on which the shine is uniquely magnificent in character. We have to know that specific gravity of this mineral is $3.4$ and when it is heated before blowpipe, the decrepitation of diaspora occurs violently and they break up into scales which appear as pearl white.
Now, let us predict the chemical formula of diaspora from the given options.
Option (A) $A{l_2}{O_3}.3{H_2}O$ is incorrect because the triple hydrated aluminum oxide is gibbsite. So, this is incorrect.
Option (B) $A{l_2}{O_3}.2{H_2}O$ is also incorrect because the double hydrated aluminum oxide is bauxite. So, we can say this is incorrect.
Now coming to option (C) $A{l_2}{O_3}.{H_2}O$, this is correct because mono hydrated aluminum oxide is diaspora. Option (C) is correct.
Option (D) is incorrect because aluminum oxide that is not hydrated is corundum.

Therefore, we can say that the chemical formula of diaspora is $A{l_2}{O_3}.{H_2}O$. Option (C) is correct.

Note: The mineral diaspora happens as a modification result of corundum or emery and is found in granular limestone and other glasslike rocks. Diaspore, alongside gibbsite and boehmite, is a significant segment of the aluminum metal bauxite. We can say that it is vapid or grayish-white, yellowish, and then violet in appearance, and shifts from clear to translucent.