The chemical formula for calcium sulfate hemihydrate, CaSO₄·0.5H₂O, indicates the presence of only half a water molecule. This is because hemihydrate means “half hydrate.” In the process of forming calcium sulfate hemihydrate, one water molecule is released, leading to the representation of half a water molecule in the formula. The dot in the formula indicates the water content, and the coefficient “0.5” signifies that only half of a water molecule is associated with each unit of calcium sulfate hemihydrate, reflecting the specific stoichiometry of the compound.