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Do Now

Do Now. Sit SILENTLY and answer the following in your notes. You do not have to copy the questions, though I am confident some of you will still ask…le sigh What are the 2 atoms that make up a water molecule? Balance the following… ___H 2 + ____O 2  ____H 2 O

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Do Now

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  1. Do Now • Sit SILENTLY and answer the following in your notes. You do not have to copy the questions, though I am confident some of you will still ask…le sigh • What are the 2 atoms that make up a water molecule? • Balance the following… • ___H2 + ____O2 ____H2O • If water changes from a solid to a liquid to a gas then it is undergoing what kind of change? How do you know? • What are some ways that we as humans pollute water systems?

  2. What makes water so special?

  3. H H Water • A water molecule (H2O), is made up of threeatoms --- one oxygen and two hydrogen. O

  4. Special Properties • Water is the only substance on Earth that occurs naturally as a solid, a liquid, and a gas. • It is often referred to as ‘the universal solvent’because so many other substances dissolve in it. • This characteristic is one reason that the water encountered on Earth is rarely pure.

  5. So…what makes water so special?

  6. Water is Polar!!!! • The oxygen end “acts”negative • The hydrogen end “acts”positive • Causes the water to be POLAR, like a magnet.

  7. Hydrogen Bonds Exist Between Water Molecules • Formed between a highly Electronegative atom (like oxygen in another water) of a polar molecule and a hydrogen • Weak bond, but strong in great numbers

  8. Interaction Between Water Molecules Negative Oxygen end of one water molecule is attracted to the Positive Hydrogen end of another water molecule to form a HYDROGEN BOND

  9. What are the Properties of Water?

  10. Properties of Water • Cohesion

  11. Properties of Water • Cohesion • Adhesion

  12. Properties of Water • Cohesion • Adhesion • High Specific Heat

  13. Properties of Water • Cohesion • Adhesion • High Specific Heat • High Heat of Vaporization

  14. Properties of Water • Cohesion • Adhesion • High Specific Heat • High Heat of Vaporization • Less Dense as a Solid

  15. Cohesion • Attraction between particles of the same substance (why water is attracted to itself) • Results in surface tension (a measure of the strength of water’s surface)

  16. Cohesion … Helps insects walk across water, but how is it helpful to people?

  17. Adhesion • Attraction between two different substances. • Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. • Capillaryaction-water molecules will “tow” each other along when in a thin glass tube.

  18. Adhesion Causes Capillary Action Which gives water the ability to “climb” structures

  19. High Specific Heat • Amount of heat needed to raise or lower 1g of a substance 1° C. • Water resiststemperature change, both for heating and cooling. • Would you rather walk on sand or in water on a beach on a hot summer day? • Which would be warmer that night? Why?

  20. High Heat of Vaporization

  21. Water vapor forms a kind of global ‘‘blanket” which helps to keep the Earth warm. • Heat radiated from the sun warmed surface of the earth is absorbed and held by the vapor.

  22. Water is Less Dense as a Solid • Which is ice and which is water?

  23. Exit Ticket Draw a water molecule with labeled atoms and charges. What is the property called that describes water sticking to itself? Is ice les dense or more dense than liquid water? How do you know?

  24. Do Now • Why is water’s property of high heat of vaporization important to the earth and more specifically to us? • What 2 properties of water are important for plants specifically and why? • Explain why solid water (ice) is able to float on liquid water.

  25. Water Distribution • Water covers approximately 71% of the Earth’s surface (USGS). Most of this water (97%) is not drinkable because it is saltwater.

  26. Water Distribution • The majority of freshwater (3%) exists in ice caps, glaciers, and oceans. • 77% of the freshwater is frozen. Of the 23% that is not frozen, approximately a half of a percent is available to supply living organisms with what they need to survive. • The availability of water varies with local geography and allows humans to utilize water as a resource.

  27. Salinity • Salinity = total amount of solid material dissolved in water • Can be determined by measuring water conductivity • Typically expressed in parts per thousand (‰) Figure 5-15

  28. So why is the Ocean so Salty?! • Dissolved chemicals eroded from the Earth's crust and washed into the sea. • Solid and gaseous ejections from volcanoes, suspended particles swept to the ocean from the land by onshore winds, and materials dissolved from sediments deposited on the ocean floor have also contributed.

  29. Salinity Cont. • Salinity in ocean waters is increased by evaporation or by freezing of sea ice and it is decreased as a result of rainfall, runoff, or the melting of ice. The average salinity of seawater is 35 parts per thousand(3.5%). Salinities are much less than average in coastal waters, in the polar seas, and near the mouths of large rivers. • In recent years, salinity has been changing across the world’s oceans. Why do you think that is?

  30. Processes affecting seawater salinity • Processes that decrease seawater salinity: • Precipitation • Runoff • Icebergs melting • Sea ice melting • Processes that increase seawater salinity: • Sea ice forming • Evaporation • Hydrothermal vents

  31. What are Hydrothermal Vents?

  32. Hydrothermal Vent • Hydrothermal vent- a deep-sea hot spring where heated seawater forces its way up through the crust. • Discovered rich communities in 1977. • Temperatures range from 10-20⁰C (50-68⁰F) to 350⁰C (660⁰F). • Mineral particles such as sulfides and carbonates precipitate to form chimneys.

  33. Mid-Ocean Ridge

  34. Hydrothermal Vents

  35. Where are vents located? Where magma is close to the surface – Mid Ocean Ridges.

  36. Mid-Ocean Ridges http://www.divediscover.whoi.edu/ridge/axial.html

  37. 19771st vent found by Alvin

  38. Alvin?

  39. Alvinhttp://www.youtube.com/watch?v=XotF9fzo4Vo

  40. Submersibles, ROVs, & AUVs

  41. How are vents created? • STEP 1 • Cold water (2oC) seeps through cracks and is heated up (up to 400oC) http://www.divediscover.whoi.edu/vents/vent-infomod.html

  42. STEP 2 • Water heated to 350-400oC – high temps. facilitate leaching of minerals from rock. • Oxygen is removed chemically • Picks up dissolved metals (Fe, Cu, Zn). • H20 picks up Hydrogen sulfide.

  43. STEP 3 • Hot liquid under pressure finds an exit. • Dissolved metals and H2S are carried up and out. • Effluent is acidic and toxic to most animals.

  44. White and Black Smokers

  45. Black Smoker Hottest of all vents

  46. monosulfide. This compound gives the smoker its black color. They spew mostly iron and sulfide, which combine to form iron monosulfide. This compound gives the smoker its black color.

  47. WHITE SMOKERS • White smoke contains silica • Anhydrite is created (white mineral) • Contains compounds of barium, calcium, and silicon • Still hot enough to cook pasta – but not as hot as black smokers

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