(c) McGraw Hill Ryerson 2007

10.2 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 368 - 370

from the World Ocean Atlas 2001

(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

(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

Density of ocean water (kg /m3) =

Mass (kg)Volume (m3)

Take the Section 10.2 Quiz