1. The Sea Around Us Lecture 3: Properties of Water: The Wonder Substance Today’s music: Dave Matthews Band “Don’t Drink the Water” Bill Nye the Science Guy Water Cycle Jump! The Who “Water” From: A Gentle Introduction to Water www.chem1.com/acad/ sci/aboutwater.html

2. Lecture Review Questions:Lecture Review Questions: TA Office Hours (T & W 11-12) On-line Assignment 1 is due tonight by 11pm Homework 1 will be posted soon Cell Phone Recycling Book pics! (Angel dropbox) Thanks to ESMARLIN R. Read Chap. 5 of Trujillo and Thurman (on reserve in EMS Library, Deike Bld)

3. Climate secrets of Mariana Trench probed (BBC news) The international team used a submersible, designed to withstand immense pressures, to study the bottom of the 10.9km-deep “underwater canyon.” Their early results reveal that ocean trenches are acting as carbon sinks. This suggests that they play a larger role in regulating the Earth's chemistry and climate than was thought. http://www.bbc.co.uk/news/science -environment-12183244 Fish eating at 7.7km depth Oceans in the News17/01/11

4. Where Did the Oceans Come From?

5. Empirical vs Belief-Based Approaches Truth is based on authority (of texts, self- proclaimed or selected leaders, legends, etc.) and is generally inviolable. Truth is based on application of a standardized method and repeated tests to confirm a result, and is subject to change as new methods are developed and new results discovered. In other words, theories evolve…

6. Belief-based vs. empirical approaches to knowledge The Source Of Authority? Belief system Definitions are simply decrees. They are not based on Science

7. The Theory of Evolution is Based on The Scientific Method A theory based on scientific principles and rigorously tested by skeptical scientists for over a century and a half!

8. 15% of your grade is based on in Class Exercises (using clickers) Marone’s Theory of Grades

9. Empirical* system: Measurements Observations Hypotheses Theories Scientific Method Parameter “X” Parameter “Y” “Correlations” *empirical means “experiential” or “searching for interrelationships”

10. Scientific method: definitions FACT : observation repeatedly confirmed HYPOTHESIS: testable statement about the natural world (a working model) THEORY: a set of verified hypotheses that explain how things work. A theory explains most or perhaps all of the observations, but ‘the jury is still out,’ for one reason or another. LAW: generalization of how some aspect of natural world behaves under stated circumstances; repeatedly-verified explanation of some aspect of the natural world

11. 1. Initial observation of materials/phenomena/behavior 2. Development of questions/establishment of constraints 3. Formulation of models to explain behavior: MULTIPLE WORKING HYPOTHESES 4. Testing of hypotheses through observation/experiment; COLLECTION OF DATA (MEASUREMENTS) 5. Analysis of data, evaluation/interpretation of results (ELIMINATE HYPOTHESES) 6. Formulate conclusions. THE SCIENTIFIC METHOD

12. Scientific Method Hypotheses and Theories must be falsifiable. That is, we can never “prove” an hypothesis, we can only disprove it We must accept some uncertainty until substantial observations and tests have been conducted. Some problems do not yield easily and answers are complex (for example--the origin of water on Earth; the carbon cycle; global climate, earthquake prediction Hypotheses and Theories must be falsifiable. That is, we can never “prove” an hypothesis, we can only disprove it We must accept some uncertainty until substantial observations and tests have been conducted. Some problems do not yield easily and answers are complex (for example--the origin of water on Earth; the carbon cycle; global climate, earthquake prediction

13. The Habitable Zone Where did Earth’s Water Come From? And Why is it Still Here?

14. Seawater Origin and Evolution Earth: The Third Stone from the Sun (Jimi is not dead!) The chemical evolution of Earth’s ocean and atmosphere is intimately related to the processes that formed the Earth--the water planet. Why does Earth have liquid water whereas the other planets do not at present? Or do they? Where’s Pluto?

18. Seawater Origin and Evolution Is it a planet ?! The chemical evolution of Earth’s ocean and atmosphere is intimately related to the processes that formed the Earth-- the water planet. Why does Earth have liquid water whereas the other planets do not at present? Or do they? The “Goldilocks Principle”

19. Planetary mass High gravity retains light volatile gases = thick atmosphere Low gravity loses all atmospheric gases Boiling breaks chem bonds Freezing stops all biochem rxns 0° 100° LIFE ZONE s o l i d l i q u i d g a s SURFACE TEMPERATURE Distance from sun The “Goldilocks Principle” * (°C) ATMOSPHERIC COMPOSITION INTERNAL COMPOSITION http://www3.geosc.psu.edu/geosc040/40.lecture_files/

20. NASA “Global Surveyor” mission map of ancient oceans on Mars (orbiter, 1997) WATER on MARS 4 BILLION YEARS AGO? Photos and mosaic JPL/ NASA The Grand Canyon of Mars - Valles Marineris 3000 km Water-formed gullies in crater

21. Summary: Origin of Water on Earth and in the Oceans Two Major Hypotheses Earth Belch –degassing of volatile chemical species (water, C02, etc. Substances easily driven off by heat Volcanic Eruptions, Hot Springs, Seafloor Vents E.T ? Comets and meteorites. Impacts big and small

22. Chat with at least 3 people around you. See if you could get together with them to go over course materials and study for exams in this course. Does the person on your right live A) On campus B) Off campus

23. This image shows the distribution of Earth’s surface water. Which is/are correct? A) Most of Earth’s surface water is in the Ocean B) Rivers and Lakes account for more water than the Atlantic Ocean C) Land ice (glaciers) account for most of the surface water that’s not in the ocean D) A and C E) Rain and clouds contain as much water as the ocean

24. Water in the world ocean came from Earth’s interior A)This is a falsifiable, scientific hypothesis B) This is a known, proven fact C) This is reasonable, based on what we know about Earth’s composition and internal structure D) All of the above E) A and C

25. Ocean water most likely formed: a)During the first 0.5 x 10 9 years of Earth’s history b) Largely from emission (degassing) of materials (volatiles) from Earth’s interior c) From melting of glaciers and polar ice caps d) (a) and (c) e) (a) and (b) So, How Would You Answer This Question?

26. Water in the Oceans --and why we should be concerned about the physical properties of water Importance to Physical & Biological Processes Water’s unique physical properties cause a buffering of Earth’s surface and environmental changes, which promotes continuity of life on Earth The physical properties of water determine how oceans circulate, how heat is transferred by the ocean and atmosphere, and the way waves work.

28. Water Promotes Continuity of Life on Earth Low viscosity rapid flow to equalize pressure differences High surface tension allows wind energy to be transmitted to sea surface allows cells to hold shape --and life to form controls the behavior of water drops High heat capacity cools/warms slowly relative to land aids in heat retention & transport minimizes extremes in temperature helps to maintain uniform body temps High latent heat of evaporation/precipitation very important for heat transfer between ocean & atmosphere (main source of energy for hurricanes!)

29. Properties of Water: Surface Tension, Viscosity, Compressibility Viscosity: Is the resistance to shear motion Increases as water cools Is low for water, compared to say, ketchup Low viscosity liquids pour or stir easily High viscosityWater has low viscosity

30. Properties of Water: Surface Tension, Viscosity, Compressibility Compressibility (can you squooosh it?) is: Very low for water The change in volume for a change in pressure Think about: In the ocean: pressure increases by 1 atm. (14.5 psi) for every 10 m increase in depth at 4000 m, a liter of water (at the surface) is only ~ 2% smaller Sea level would be 37m higher if water were totally incompressible After Compression before

31. Properties of Water: Surface Tension, Viscosity, Compressibility Surface tension or capillary force (highest of all liquids) cohesion of liquid surface- intermolecular forces water forms weak "elastic" membrane increases as water cools decreases with increasing salt content meniscus

32. Surface tension is what holds water drops together and determines the shape of waves. Ripples and small waves are generated by wind energy and the surface tension of water.

33. http://www.flixxy.com/water-drop.htm#.UPQpcIVe8oY%3Cp%3E Physical Properties of Water. Check out Water Drop at 2000 Frames per Second From Discovery Channel's series 'Time Warp' where MIT scientist and teacher Jeff Lieberman and digital-imaging expert Matt Kearney use the latest in high-speed photography to turn never-before-seen wonders into an experience of beauty and learning.

34. Physical Properties of Water: The Wonder Substance Molecular Structure and Organization Bonding of hydrogens to oxygen creates a "polar" molecule. Water molecule: 105° angle unequal charge distribution: Polar

35. Molecular Structure and Organization: Clustering of water molecules What causes it? hydrogen bonds (weak interaction ~10% of covalent strength) This property creates Surface Tension Liquid water; bonds are constantly breaking and reforming each bond lasts a few trillionths of a second high proportion of molecules bonded at any instant

36. Water Promotes Continuity of Life on Earth Low viscosity rapid flow to equalize pressure differences High surface tension allows wind energy to be transmitted to sea surface allows cells to hold shape --and life to form controls the behavior of water drops High heat capacity cools/warms slowly relative to land aids in heat retention & transport minimizes extremes in temperature helps to maintain uniform body temps High latent heat of evaporation very important in heat/water transfer in atmosphere

37. Properties of Water Unusual Properties--compare other liquids Heat capacity (high) only ammonia (NH3) higher H 2 0 much higher heat capacity than rock or steel Heat Capacity or Specific heat: What is it? Ability of a material to store heat Heat needed to change the temperature of a given mass of water (1 gram or 1 kilogram) by 1 degree C For Water: heat capacity is: 1 cal per gram per deg. Celsius, 1cal/(gm °C) 1 calorie is the heat energy needed to raise 1 gm by 1°C 1 calorie = 4190 J (heat capacity of water is 4190 J/Kg °C) Need 41,900 J to raise the temperature of 1 kg (1 liter) of water from 0 to 100° C

38. 3 phases of materials

39. Heat input Temperature (°C) water Heat, Temperature and Changes of Phase Which statement is correct about this plot? A.Ice changes to water at 50° C B.Heat is required to change ice to water and this is known as latent heat C.Once the ice melts, heat will cause temperature to rise, this is known as sensible heat D.B & C E.None of the above Ice 0 50 -50

40. Heat Capacity Heat required to change the temperature (by 1 °) of a given mass Heat input (J/kg or cal/gram) Temperature (°C) Liquid water Rock & Soil 4190 Kg °C J

41. Heat capacity and phase changes: ice (solid) water (liquid) vapor or steam (gas) 0 200 400600800 Heat input (cal/gram) Temperature (°C) 150 100 -100 50 0 -50 Liquid water Ice Vapor Latent Heat Heat needed to change phase (from solid to liquid, liquid to gas, liquid to solid, etc.) Latent heat of vaporization or condensation 540cal/gm Latent heat of fusion or melting 80cal/gm Ice + liquid vapor+ liquid

42. Clicker question: Which is the best answer A.Viscosity is a measure of resistance to shear motion A.A low viscosity liquid pours more slowly than a high viscosity liquid B.The viscosity of water is zero C. Water is highly compressible, which means that 1 kg of it occupies a much, much smaller volume at the bottom of the ocean than near the ocean surface D.A & D

43. Consider: two identical pots, filled with equal masses of fluid, on identical burners on a stove. Pot A is filled with a fluid of low heat capacity Pot B is filled with a fluid of high heat capacity After a time….. A.The material in Pot A has reached higher temp. B.The material in Pot B has reached higher temp. C.Both pots are at the same temp. Heat Capacity is the heat required to change the temperature (by 1 °) of a given mass of material

44. Heat input (J/kg or cal/gram) Temperature (°C) Higher Heat Capacity Lower Heat Capacity Heat Capacity Heat required to change a given mass by a given temp. J/kg or cal/gram Pepsi

45. Heat Capacity Heat required to change a given mass by a given temp. J/kg or cal/gram Heat input (J/kg or cal/gram) Temperature (°C) Higher Heat Capacity Lower Heat Capacity It’s game day, and you want to keep your Pepsi cold as long as possible. You should fill your cooler with: A.A material with high heat capacity B.A material with low heat capacity C. Doesn’t matter because you’re trying to keep it cold, not hot

46. Latent Heat and Changes of State Latent heat of fusion (or melting) Heat to form or melt ice (liquid to solid phase) 333 kJ/kg (80 calories/gram) Latent heat of vaporization (or precipitation) Heat to vaporize (boil) a liquid or condense liquid from a gas phase 2260 kJ/kg (540 calories/gram) Evaporation of water from the surface can occur at any temperature. However, it takes more energy to evaporate at low T than to boil off vapor once water reaches 100°C

47. The high heat capacity of water means that it heats up and cools off more slowly than land.

48. Latent heat is a key factor in Hurricane development and sustainability.

49. Properties of Water: Heat Capacity What is heat capacity? Why is it so high for H 2 0? Adding heat to water: speeds up molecules break bonds Hence, less warming or less evaporation than expected When heat is removed from water: bonds form and restructure, material condenses (e.g., gas to liquid) energy is released via bonds formation Energy release causes heating and thus temperature decrease is smaller than expected

50. Density of Water Fresh water reaches maximum density at 3.98 °C Density= 1,000 kg/m 3 (1kg/liter) Density decreases as water is heated above 4°C At 20 °C, density of pure H 2 O is 998.23 kg/m 3