Question

Give the chemical formula of calcium sulphate hemihydrate:
A. $\text{CaS}{{\text{O}}_{4}}.2{{\text{H}}_{2}}\text{O}$
B. $\text{CaS}{{\text{O}}_{4}}.\dfrac{1}{2}{{\text{H}}_{2}}\text{O}$
C. $\text{CaS}{{\text{O}}_{4}}.10{{\text{H}}_{2}}\text{O}$
D. $\text{CaS}{{\text{O}}_{4}}.{{\text{H}}_{2}}\text{O}$

Answer 1

For this problem, we have to study the molecule including its physical and chemical properties. The molecular formula of calcium sulphate in anhydrous and complete hydrous form can be used to determine the hemihydrate form.

Complete Step-by-Step answer:
- In the given question, we have to find the correct formula of calcium sulphate hemihydrate among the given options.
- The calcium sulfate is an inorganic compound that has a general, anhydrous molecular formula of $\text{CaS}{{\text{O}}_{4}}$.
- Plaster of Paris is the other name of calcium sulfate and obtained naturally from the mineral gypsum.
- The compound is not soluble in water and also it is non-inflammable that's why it does not catch fire easily.
- The hydrous form of the calcium sulfate will be $\text{CaS}{{\text{O}}_{4}}.{{\text{H}}_{2}}\text{O}$
- So, as we know that the hemi means half so, the hemihydrate calcium sulfate will have to be a molecular formula of $\text{CaS}{{\text{O}}_{4}}.\dfrac{1}{2}{{\text{H}}_{2}}\text{O}$.
- Bassanite is the other name of calcium sulfate hemihydrate.
- Calcium sulfate is widely used in dentistry as a bone regeneration material to heal all the deformities of the teeth and bone.
- Sometimes, calcium sulfate is used as an oxidising agent by releasing an oxygen atom when provided with a high temperature.
Therefore, option B is the correct answer..

Note: The other form of hydrate of the calcium sulfate is also found in which two molecules of water are present and that's why it is also known as a dihydrate form of calcium sulfate. Calcium sulfate is also used in food products as a coagulant.