No, H₂O is not seawater. While H₂O (water) is the primary component of seawater, comprising approximately 70-85%, seawater also contains a significant amount of dissolved salts and other substances. Seawater's salinity, typically around 3.5% (35 g/L), means that it is not pure water.
Understanding the Composition of Seawater
- Predominantly Water: Seawater is primarily composed of water molecules (H₂O), which are connected through hydrogen bonds forming structures like (H₂O)₅ pentamers, as noted by the AGU Publications article.
- Dissolved Salts and Minerals: The crucial difference is the presence of dissolved salts, primarily sodium chloride (NaCl), which contribute to its salinity. As explained in the Surfer Today article, a precise chemical formula for seawater is not possible due to the complex mixture.
- Other Substances: In addition to salts, seawater contains other dissolved minerals, organic matter, and gases.
The Reddit discussion on r/askscience highlights that dissolving salt (NaCl) into water creates a solution where the NaCl dissociates into ions (Na⁺ and Cl⁻) surrounded by water molecules, altering its properties. This demonstrates that adding even a common component drastically alters the substance's overall characteristics.
The statement from NOAA emphasizes the salinity of seawater, confirming it isn't just H₂O. Even though H₂O is a large portion of seawater, other elements are abundant.
The Wikipedia article on Seawater directly states that seawater's average salinity is about 3.5%, solidifying the fact that it's a solution of salts in water, not just pure H₂O.
