Definition

Noun: - The chemical formula for water, a transparent, odorless, tasteless liquid that is essential for all known forms of life. It freezes into ice at 0°C and boils into steam at 100°C under standard atmospheric pressure and is a universal solvent.

Usage

• is used primarily in scientific, technical, and formal contexts to refer to water in its pure chemical form.
• It is often used to emphasize the molecular composition of water.

Examples

• Scientific Context:
  • The molecule H2O consists of two hydrogen atoms bonded to one oxygen atom.
  • This experiment requires pure H2O, not tap water.
• General/Formal Context:
  • The label indicates that the solution is 99% H2O.
  • H2O is crucial for hydration and cellular function.

Advanced Usage

• In Chemical Equations: is used as a standard notation in chemical formulas and reactions.
  • The balanced equation is 2H₂ + O₂ → 2H2O.
• As a Symbol for Purity: In contexts like laboratory work or product ingredients, specifies the substance as pure water.
  • The pharmaceutical compound is dissolved in distilled H2O.

Variants and Related Words

• Water (n): The common word for the liquid form of H2O. This is the term used in everyday, non-technical language.
  • I drink eight glasses of water a day.
• Dihydrogen monoxide (n): A systematic, albeit rarely used formal name for water, highlighting its chemical composition. Often used in technical or humorous contexts.
• Aqua (n): A Latin-derived term sometimes used in scientific names (e.g., ) or commercial contexts (e.g., ).

Synonyms

• Water: The direct and most common synonym.
• Distilled water: Purified water with minerals removed, often implied by in lab contexts.
• Pure water: Water without impurities.

Notes on Usage

• is not typically used in casual conversation. Saying "I need a glass of H2O" would sound overly technical or humorous. The word "water" is always preferred for everyday communication.
• The "2" in is usually written as a subscript (H₂O) in proper chemical notation.

Noun

1. binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent