1. 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
from the World Ocean Atlas 2001
(c) McGraw Hill Ryerson 2007

2. 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
(c) McGraw Hill Ryerson 2007

3. Salt water has slightly different properties than fresh water
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
(c) McGraw Hill Ryerson 2007