Water

**Physical and Chemical Properties of Water:**
– Water is transparent, tasteless, odorless, and nearly colorless.
– Chemical formula H2O indicates two hydrogen atoms connected to one oxygen atom.
– Water covers about 71% of Earth’s surface.
– Water exists in solid, liquid, and gaseous states on Earth.
– Water plays a vital role in the global economy, agriculture, and food supply.
– Water is used as a solvent in various industrial processes and cooking.
– Water has specific thermal properties like boiling point, vapor pressure, thermal conductivity, refractive index, and viscosity.
– Water has a hexagonal crystal structure and a bent molecular shape.
– Water has a dipole moment and acidity/basicity properties.
– Water is a polar inorganic compound and the universal solvent.

**States and Properties of Water:**
– Water molecule consists of two hydrogen atoms and one oxygen atom.
– Water has three common states: solid (ice), liquid, and gas (water vapor).
– Water becomes less dense as it freezes.
– Ice has a density of 917kg/m³.
– Water boils at 100°C and freezes at 0°C at 1 atm pressure.
– Water can remain liquid at high temperatures in specific conditions.
– Water is a diamagnetic material and exhibits phase transitions like melting and boiling.
– Pressure affects the melting and boiling points of water.
– Water has triple and critical points, including a supercritical fluid phase.

**Chemical Properties and Solubility of Water:**
– Water is poorly soluble in haloalkanes, aliphatic, and aromatic hydrocarbons.
– Water has improved solubility in carboxylates, alcohols, ketones, and amines.
– Water is miscible with substances like methanol, ethanol, and acetone.
– Water is partially miscible with diethyl ether, methyl ethyl ketone, and ethyl acetate.
– Water is a good polar solvent due to hydrogen bonding and molecular polarity.

**Water Cycle and Resources:**
– Water cycle involves processes like evaporation, transpiration, precipitation, and runoff.
– Water resources include stocks like glaciers, groundwater, and flows like rivers and lakes.
– Aquifers can store water for thousands of years, while lake volumes fluctuate seasonally.
– Unsustainable groundwater withdrawals for irrigation lead to depletion.
– Global freshwater distribution: glaciers (69%), groundwater (30%), other sources (1%).

**Importance of Water in Life and Society:**
– Water is essential for all known forms of life, metabolic processes, and replication.
– Water is crucial for anabolism, catabolism, photosynthesis, respiration, and enzyme function.
– Water supports diverse aquatic life forms and is central to ecosystems.
– Access to safe drinking water is vital for human health and development.
– Water scarcity, sanitation issues, and competition for water resources pose global challenges.https://en.wikipedia.org/wiki/Water