Lesson 2 part 2

• Heterogeneous Mixtures• Parts of the mixture are noticeably different from one

another

• Homogenous Mixtures• Evenly distributed, hard to tell the difference between one

part and another

• Type of homogenous mixture• When substances dissolve in another• Particles are too small to settle out, filtered or

scatter light

• Water has many properties, but one of the most important is that water acts as a UNIVERSAL solvent• Solvent – Substance that does the dissolving• Solute – Substance that dissolves in the solvent

• The solubility of a substance is its ability to dissolve another substance• Water is very good at dissolving• Hot water can hold more solute (can dissolve more) than

cold water

• Water’s polarity contribute to water as a universal solvent

• Salt is part metal, part nonmetal• Metal and nonmetal bonding form ionic bonds

• Ionic bonds form from IONS• Elements that have a + or – charge• Opposites Attract

• Ocean is filled with dissolved particles• Elements that have opposite electrical charges are called

SALTS• This makes a Saline solution• Na, Cl, Sulfate, Magnesium, Calcium, Potassium, Bicarbonate

• Distilled water = no salinity • Fresh water is .01% salt or less• Ocean average is 3.5% salt or more

• Every liter has 1.2 ounces of salt

• Water’s excellent ability to dissolve solutes means it is carrying materials with it• Water does the same in all organisms

• Where do these salts come from?• Fresh water & streams contain salts• Rivers dump into the oceans

• 4 billion tons of salts are emptied into the oceans each year

• Water also evaporates• Leaves behind salts

• Inside the Earth• Deep Sea Vents

• From the Atmosphere• Wind and Rain carry minerals• Human made

• Only removed by incorporating into rocks, sediments and organisms

• Marine organisms are designed to live in the salt water

• Brackish = in between salty or fresh• Mangrove forests and salt marshes

• Called estuaries• Where rivers meet oceans• Many juvenile organisms live here

• “Nursery of the Sea”

• Also protect coastlines from erosion

• Marine organisms go through Osmosis• Water moves from low salinity (high water concentration)

to high salinity (lower water concentration

• Osmoconformers-• Do not attempt to control solute/water balance• Their internal concentration varies as the salinity in the

water around them changes• Most can only tolerate a very narrow range of salinity

• Osmoregulators– These organisms control their internal concentrations– Can generally tolerate a wider range of salinities than

osmoconformers– Some animals require different amounts of salt for

different life-cycles– This can be done in a variety of ways such as secreting

very little urine or using specialized glands to secrete salts as examples

• Osmoregulation – Individual cells control the balance of water• Mangroves will release salt from their leaves

• Some sea turtles and marine birds have special salt glands that remove excess salt

• In high salt environments, fish and other organisms lose water to the salty sea • Must drink more water• Adding more salts

• Need a way to remove the excess salts and maintain homeostasis• Constant internal environment• Opposite for Freshwater Fish

• This way cells stay the same size

• Marine MAMMALS• Do not drink sea water

• Get water from the food they eat and have a higher urine salt concentration

• Maintain neutral buoyancy• Float, sink

Less dense than water