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 crisis in the Democratic Republic of the Congo DRC, the actual number of people without water access is increasing at a significantly higher rate in urban areas because of faster population growth. The average annual growth rate of the urban population over the time period from 2010 to 2015 was estimated at 4 percent, compared to a population growth rate of 1.9 percent in rural areas. The population living in urban areas is estimated at 42 percent. The rapid population growth in urban areas is associated with the expansion of the urban sprawl and poses major difficulties in establishing adequate water infrastructure. Many peri-urban watersheds are being impacted