Section B: Give a very short answer to the question given below.
21.a. On heating 'X' at 373K, it loses water molecules and becomes 'Y'. 'Y' is a substance which doctors use for supporting fractured bones in the righ position.
i. Identify 'X' and 'Y'.
ii. How can 'X' be reobtained from 'Y'?
ii. How can 'X' be reobtained from 'Y'?
Gypsum loses water molecules upon heating and converts into plaster of Paris, which doctors commonly use to support fractured bones in the correct position.
To get back (X) from the (Y), mix the plaster of Paris with water. The plaster of Paris reacts with water and sets into a hard, solid mass of gypsum.
\(CaSO_4⋅0.5H_2O\) + \(1.5H_2O\) → \(CaSO_4⋅2H_2O\)
This reaction, known as the rehydration process, is a fascinating example of chemical transformation. Plaster of Paris (CaSO₄·0.5H₂O) converts back into gypsum (CaSO₄·2H₂O) when mixed with water.
Therefore, the 'X' is (CaSO₄·2H₂O), a mineral composed of calcium sulfate dihydrate and the 'Y' is (CaSO₄·0.5H₂O or (CaSO₄)₂·H₂O), which is obtained by heating gypsum to 373 K (100°C).