Define and discuss hydrates, anhydrous, and hydrous. Review the water of hydration formulas. Using a known hydrate, hydrated barium chloride, work through, step by step, procedure to determine the water of hydration. This involves not only the physical method but also the mathematical formulation, and determination of moles of water and anhydrous barium sulfate. Once moles are determined, the mole ratio is found which will determine the moles of water attached to each mole of barium.