What is water?

Answer 1

Water is a chemical substance with the molecular formula H₂O. It consists of two hydrogen atoms covalently bonded to one oxygen atom. Water is essential for all known forms of life and covers about 71% of the Earth's surface, primarily in oceans, seas, rivers, lakes, and glaciers.

Key properties of water include:

1. **Polarity**: Water molecules have a polar nature due to the difference in electronegativity between oxygen and hydrogen, creating a partial positive charge near the hydrogen atoms and a partial negative charge near the oxygen atom. This polarity allows water to dissolve many substances, earning it the title of a "universal solvent."

2. **Hydrogen Bonding**: The polarity allows water molecules to form hydrogen bonds with each other, leading to unique properties such as high surface tension, cohesion, and adhesion. Hydrogen bonds also contribute to water's relatively high boiling point and melting point compared to other similar-sized molecules.

3. **Density and Phase Changes**: Water has an unusual density behavior in that it is most dense at 4°C. Ice, the solid phase of water, is less dense than liquid water, causing it to float. This property is crucial for aquatic life, as it insulates the water below and creates a stable environment.

4. **Thermal Properties**: Water has a high specific heat capacity, which means it can absorb or release a considerable amount of heat with minimal temperature change. This property helps in moderating Earth's climate and maintaining stable conditions within organisms.

5. **pH and Ionization**: Pure water has a neutral pH of approximately 7. However, water can ionize to a very small extent to produce hydrogen ions (H⁺) and hydroxide ions (OH⁻), contributing to its ability to participate in acid-base reactions.

Water plays a vital role in various biological, geological, and chemical processes. It is crucial for hydration, biochemical reactions, temperature regulation, nutrient transport, and many other functions within living organisms and the environment.