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Salt water, or seawater is water from a sea or ocean. On average, salt water in the world's oceans have a salinity of about 3.5% (35g/L or 599 mM). This means that every kilogram (roughly 1 liter by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts (predominately sodium (Na+) and cholride (Cl-) ions). Average density at the surface is 1.025 kg/L. Seawater is denser than both freshwater and pure water because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. Seawater pH is typically limited to a range betwen 7.5 and 8.4.
Animals that live in salt water