2) Alum has twelve hydrated water molecules. Are these included in the molecular weight?
Why?

The dot between KAl(SO4)2 and 12 H2O in the formula indicates that twelve moles of water are associated with every mole of KAl(SO4)2. Therefore, the mass of the twelve water molecules, called the waters of hydration, must be included in the molecular weight of the compound.

Explanation:

Explanation:

This alum is widely used to dye fabrics, make pickles crunchy, and manufacture paper. It is also used as a coagulant in water purification and as an astringent in medicine. ... Therefore, the mass of the twelve water molecules, called the waters of hydration, must be included in the molecular weight of the compound.