acqua

Acqua is the Italian word for water and one of the most abundant substances on Earth. In science, water is a chemical compound with the formula H2O, consisting of two hydrogen atoms bonded to one oxygen atom. Water is essential for all known forms of life and acts as a universal solvent.

Etymology: The term derives from Latin aqua, cognate with many languages’ words for water.

Properties: At room temperature water is a colorless, tasteless liquid. It has a density of about 1 g/cm3 at 4 C, a high heat capacity, and a strong capacity to dissolve many substances because of its polarity. Water exhibits hydrogen bonding and shows a density maximum near 4 C.

Occurrence and cycle: Most of Earth’s liquid water is in oceans; freshwater accounts for a small fraction, with most of it locked in glaciers or subterranean aquifers. The water cycle includes evaporation, condensation, precipitation, infiltration and runoff.

Uses and management: Water is drawn for drinking, irrigation, industry and energy production. Water treatment involves filtration and disinfection to reduce pathogens and contaminants. Access to safe drinking water and adequate sanitation is a major global policy concern.

Health and environment: Water is essential for health and ecosystems, but contamination with microbes, chemicals or heavy metals can cause illness. Climate change and overuse threaten availability in many regions, prompting conservation, infrastructure investment and sustainable management.

See also: Hydrosphere, Water cycle, Aquifer.