Water of crystallization degree of hydration can be critical to the resulting chemical properties. For example, anhydrous RhCl is not soluble in water and is relatively useless in organometallic chemistry whereas RhCl•3HO is versatile. Similarly, hydrated AlCl is a poor Lewis acid and thus inactive as a catalyst for Friedel-Crafts reactions. Samples of AlCl must therefore be protected from atmospheric moisture to preclude the formation of hydrates. Crystals of hydrated copper(II) sulfate consist of [Cu(HO)] centers linked to SO ions. Copper is surrounded by six oxygen atoms, provided by two different sulfate groups and four molecules of water. A fifth water resides elsewhere
Water management in the Metropolitan Region of São Paulo developed from the Iguape river in the Ribeira valley 80 km to the south of MRSP. Furthermore, the efficiency of existing water use is expected to be increased through more reuse of treated wastewater and further reductions in water losses. The first modern water supply system for São Paulo was built by a private company, the Cantareira Water Supply and Drainage Company of the City of São Paulo, in the 1880s. The company built a pipeline from the Cantareira mountains in the North to São Paulo, which would become the first element of what would later become the Cantareira system