Ocean Water Vs. Fresh Water How are they different? Ch 10.2

Ocean water has more salt so it has a higher salinity The Salinity of Water Have you ever tried drinking ocean water? It is very salty!!! Ocean water is about 200x saltier than fresh water! The amount of salt in the water is known as salinity. Ocean water has more salt so it has a higher salinity

The Salinity of OCEAN WATER The salinity of salt water is not the same everywhere in the world.... At the equator.... -temperatures are high - water evaporates in the oceans - this leaves salt behind (water is more salty!) Equator

The Salinity of OCEAN WATER At the North and South Poles - temperatures are low and water freezes - this leaves salt behind as well - water has high salinity

The Salinity of OCEAN WATER Near the continents - freshwater from rivers empties into the oceans - since the river waters are fresh water (little salt), it dilutes the ocean water near the continents River water (fresh water) Ocean water (salt water)

Composition of Salt Water Salt is the main component of salt water What is salt made of...? Salt is made of two ions Chloride ions (Cl-) Sodium ions (Na+) These ions form Sodium Chloride (or salt)

Where Does the salt come from? From the land: Rain falls on the land and makes it way to streams and rivers When water travels through the ground , it picks up materials (such as salt). We call these materials dissolved solids. Eventually these materials get into the oceans In the oceans, the dissolved solids are well mixed because the water is moving constantly

Dissolved solids are in the ground Dissolved solids are in the ground. As the water seeps from the ground into streams and rivers, it carries the solids with it. Eventually they end up in the oceans.

Where Does the salt come from? (2) From volcanoes: Undersea volcanoes spew materials into the water On land, volcanoes spew materials into the atmosphere (these materials condense in clouds and are returned to the oceans when it rains) Under water volcano African volcano

Lava going into the ocean at Hawaii’s Volcanoes National Park

Density of salt water D = m/V Recall that density = mass/ volume Salt water is denser than freshwater because of the particles of NaCl! D = m/V Density (salt water) = 1027 kg/cm3 Density (freshwater) = 1000 kg/cm3 NaCl increases the mass of water

Density of salt water Because salt water is denser than freshwater, you will float more easily in very salty oceans or seas!

Freezing point of salt water Normally water freezes at 0°C Adding salt to water causes the freezing point to lower (-1.9°C ) So the freezing point of salt water is LOWER than fresh water. This is also why we add salt to the roads in the winter!

Understanding Check How much saltier is ocean water than fresh water? Why do the world’s oceans contain so much more salt than fresh water does? Name two main dissolved solids found in ocean water Why is the freezing point of salt water lower than that of fresh water?