Lesson 3.2:Salinity

*Refer to Chapter 8 in your Textbook

Learning Goals:

1. I can differentiate between compounds, mixtures, and solutions.

2. I can explain why the ocean is salty. 3. I can explain how marine organisms

osmoregulate.

Compounds• Compound: a substance formed by the chemical

combination of two or more elements using ionic bonds Na (Sodium) + Cl (Chlorine) NaCl (Salt)

Mixtures• Mixture: two or more elements or compounds

that are physically combined but not chemically combined

• Suspensions: material that does not dissolve in a mixture

Solutions• Solution: two or more elements or compounds

that are mixed completely • Solute: substance being dissolved (ex. salt) • Solvent: dissolver (ex. water)

Solute + Solvent = Solution

SolubilitySolubility: A solutes ability to be dissolved in

a solventAs temperature increases, solubility increases (Ex. Sugar dissolves better in hot coffee over iced)

SalinityThe ocean is a solution of water and

dissolved materialsSalinity is the measure of dissolved solids in

the waterAverage salinity of the ocean = 35 pptPPT = “parts per thousand” grams of salt per liter water

Types of Dissolved SolidsMajority is table salt: Sodium Chloride

(NaCl)Dissolved Solids in the Ocean:

Chloride (Cl) 18.98 gramsSodium (Na) 10.56 gramsSulfate (SO4) 2.65 gramsMagnesium (Mg) 1.28 gramsOther 0.61 gramsCalcium (Ca) 0.4 gramsPotassium (K) 0.38 gramsBicarbonate (HCO3) 0.14 grams

Where does the Salt Come From?Water is an excellent solvent, which implies

that wherever there is water, it is carrying materials with it

1) From land:Particles transported via freshwater streams and rivers

2) From the atmosphere:Particles transported via wind

3) From inside the Earth:Minerals are spewed out of volcanoes and hydrothermal vents

How does Salinity & Temperature Affect Density?

Salinity & Density: The greater the salinity, the greater the densityThe greater the density, the better you float

Temperature & Density: The lower the temperature, the greater the

densityCold, salty water sinks!

Salinity and Marine Organisms Osmosis

The movement of solvent through a semipermeable membrane to an area of higher solute concentration

Moves High-to-Low

Salinity and Marine Organisms Hypertonic: water out, causes shriveling Isotonic: neutral Hypotonic: water in, causes swelling

Salinity and Marine Organisms Freshwater Fish:

Put in saltwater would be a hypertonic solution, causing the fish to shrivel & dehydrate

Saltwater Fish: Put in freshwater would be a hypotonic

solution, causing the fish to swell and burst from water pressure

Salinity and Marine Organisms Osmoregulation: balancing the amount of

water and salt in your body to remain isotonic Freshwater Fish:

Gain water through osmosis & food Absorb salt through gills & foodDilute watery urine

Saltwater Fish: Gain water and salt through eating and

drinking Lose water and salt through osmosisSalty urine

Osmoregulation