Question

A white powdery compound of calcium is used for making toys and cast of statues. It hardens when mixed with water. Identify the compound. Write the chemical equation of its preparation.​

Answer 1

Answer:

The powdered substance is Calcium sulphate hemihydrate ($\sf CaSO_4.\dfrac{1}{2}H_2O)$

When it is mixed with water, the reaction takes place :

$\sf CaSO_4.\dfrac{1}{2}H_2O(s) + \dfrac{1}{2}H_2O(l) \longrightarrow CaSO_4.2H_2O(s)$

The powdered substance can be obtained via heating of $\sf CaSO_4.2H_2O$ as :

$\sf CaSO_4.2H_2O(s) \displaystyle \longrightarrow^{\triangle} \sf CaSO_4.\dfrac{1}{2}H_2O(s)+ \dfrac{1}{2}H_2O(g)$