(c) McGraw Hill Ryerson How Ocean Water Differs from Fresh Water Ocean water’s salinity = 200X greater than fresh water  Average salinity of oceans is 35 parts per thousand  Oceans at equator (evaporation) and poles (ice) have the highest salinity (removing water increases salinity)  Ocean locations near rivers have low salinity, due to addition of fresh water See page from the World Ocean Atlas 2001World Ocean Atlas

(c) McGraw Hill Ryerson 2007 Composition of Salt Water Salt water is composed of minerals dissolved during run-offs occurring over millions of years  Volcanic eruptions also release minerals from inside Earth  Sodium ions (Na + ) and chloride ions (Cl - ) are most common solids in ocean water  Na + ions and Cl - ions > 75% of all solids in ocean water  Mixed and joined in the ocean, NaCl is chemical name for salt See page 370

Composition of Salt Water (c) McGraw Hill Ryerson 2007

Density of Salt Water  Density = how tightly packed the molecules are in an object  Less dense always floats on more dense  Eg. warm air rises above cool air, and oil floats on water  We float better in salt water than fresh water Salt water has slightly different properties than fresh water  Salt water freezes at –1.9 ºC See page 371 Take the Section 10.2 Quiz