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The S-Block Elements

Question
CBSEENCH11007164
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What is Gypsum? How is it prepared? What are its properties and uses?

Solution
Gypsum is hydrated calcium sulphate, CaSO4.2H2O
Preparation: It can be prepared by the action of dilute sulphuric acid on calcium carbonate or calcium hydroxide.
CaCO subscript 3 left parenthesis straight s right parenthesis space plus space straight H subscript 2 SO subscript 4 left parenthesis aq right parenthesis space space rightwards arrow space space CaSO subscript 4 left parenthesis straight s right parenthesis space plus space CO subscript 2 left parenthesis straight g right parenthesis space plus space straight H subscript 2 straight O left parenthesis straight l right parenthesis Ca left parenthesis OH right parenthesis subscript 2 left parenthesis aq right parenthesis space plus space straight H subscript 2 SO subscript 4 left parenthesis aq right parenthesis space rightwards arrow space space space CaSO subscript 4 left parenthesis straight s right parenthesis space plus space 2 straight H subscript 2 straight O left parenthesis straight l right parenthesis
Properties:
(i) It is a white crystalline solid sparingly soluble in water.
(ii) On heating to 393 K, it changes into CaSO subscript 4. space 1 half straight H subscript 2 straight O left parenthesis Plaster space of space Paris right parenthesis. 
On heating to about 437 K, it changes into anhydrous calcium sulphate. 

                        stack CaSO subscript 4. space 2 straight H subscript 2 straight O with Gypsum below space rightwards arrow with 390 on top stack space CaSO subscript 4.1 half straight H subscript 2 straight O with Plaster space of space Paris below space space rightwards arrow from 473 straight K to Above of space CaSO subscript 4
 
Uses. It is used: 
(i) in the manufacture of cement. 
(ii) for manufacturing Plaster of Paris
(iii) as a drying agent. 
(iv) for the preparation of ammonia, bleaching powder slaked lime and basic calcium nitrate. 

Some More Questions From The s-Block Elements Chapter

Group 1 elements are called alkali metals. Why?

Why caesium can be used in photoelectric cell while lithium can not be?

In aqueous solution, Li+ ion has lowest mobility. Why?

Lithium has highest ionisation energy in group 1 elements, yet it is strongest reducing agent. Comment.

The softness of group 1 elements increases down the group with increasing atomic number. Give reason. 

Which is the most reactive alkali metal and why?

Why alkali metals do not form M2+ ions?

Name the radio active element in group 1. How does it resemble with the remaining elements of the group?

Why alkali metals are normally kept in kerosene oil?

Why lithium cannot be stored in kerosene?

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