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Post LAB: Clinging Molecules

Post LAB: Clinging Molecules. Properties of Water. Water’s Properties. Surface Tension :Cohesion and Adhesion Solid water (ice) is less dense than liquid Capillary Action High Specific Heat High Heat of Vaporization High Heat of Fusion Solvent Transparent. 3 - States of Water.

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Post LAB: Clinging Molecules

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  1. Post LAB: Clinging Molecules Properties of Water

  2. Water’s Properties • Surface Tension:Cohesion and Adhesion • Solid water (ice) is less dense than liquid • Capillary Action • High Specific Heat • High Heat of Vaporization • High Heat of Fusion • Solvent • Transparent

  3. 3 - States of Water • < 0o C = ice • 0o C - 100o C = • liquid • 100 o C = steam

  4. Properties of Water

  5. Freeze! • Can of Soda room temperature • Can of Soda frozen Water expands when it freezes

  6. Freeze! Myfavorite

  7. Expansion of Ice Ice expands when water freezes compared to most substances that contract when freezing

  8. Hexagonal Ice Ice crystals in a Cave Hydrogen bonds

  9. http://www.lummox.net/celestial/pics/ak1999sundog.jpg Halos, Sundogs, & Pillars are caused by hexagonal ice crystals

  10. Ponds Freezing Solid water (ice) has a lower density than liquid water High Heat of Fusion:Ice freezes from the top down.Takes longer for lakes to freeze, allowing living things more time to adjust.

  11. Ice good insulator, floats, living things don’t freeze beneath (3.8 °C ) ICE FISHING

  12. Float and Sink • Place paperclip gently on the water. • Surface tension • (unequal attraction of particles in the surface layer )

  13. Float and Sink

  14. Cohesion • Water clings to polar molecules through hydrogen bonding • Cohesion refers to attraction to other water molecules. • responsible for surface tension

  15. Adhesion • Adhesionrefers toattraction to other substances. • Water is adhesive to any substance with which it can form hydrogen bonds.

  16. Clinging Molecules • How many drops will “fit” on penny before it spills over edge? Surface tension

  17. How many drops can you get on a penny? Water? Alcohol? Vegetable Oil? Why is there a difference??? Water[HOH] has stronger weak Hydrogen Bonds Alcohol [(CH3)2CHOH] has weaker forces Vegetable oil [(CH3)(CH2)16COOH]is non-polar… very weak forces

  18. Surface Tension Enhancement of the intermolecular attractive forces at the surface

  19. What causes surface tension? Cohesive forces between molecules are shared with all neighboring atoms. Since the surface has no neighboring atoms above, they exhibit stronger attractive forces for their neighbors next to and below them

  20. Surface tension is a result of cohesive intermolecular forces

  21. water evaporates from leaves = transpiration All thanks to hydrogen bonding! Capillary action adhesion, cohesion and capillary action water taken up by roots

  22. To Wax Philosophic • Wax paper • Water and dropper • Drag tip of dropper around wax paper Surface tension

  23. Add soap.. What happens? Why?

  24. How is surface tension affected by soap? Breaks the surface tension!

  25. Shape of water drop NOT TEAR shaped

  26. Polarity Separation of charge An asymmetrical difference in electronegativity along a bond or in a molecule

  27. Cl Al O N Cl H H H Cl H H Cl S O C O Cl C Cl H H Cl Circle the polar molecules. Label d+ and d- d- d- d+ d+ d- d+

  28. Non-Polar 104.5o ( Bent) 1. __________ molecules are symmetrical 2. What is the bond angle in H2O?__________ 3. The motion of particles in these phases:Solid LiquidGas

  29. Electrostatic Forces Small, weak interactions between molecules

  30. Electrostatic Forces Intermolecular: between molecules (not a bond) Intramolecular: bonds within molecules (stronger)

  31. THE DISSOLVING PROCESSSolvent • Intermolecular Forces: “Like dissolves like”

  32. Miscible / Immiscible:Two liquids are miscible in each other if they readily mix to form a uniform solution. Two immiscible liquids will always separate out into two distinct layers.

  33. Graduated Cylinder • Water. Oil. alcohol Water is POLAR and oil is NON-POLAR Oil is less dense than water so it floats on water Alcohol

  34. (HIGH SPECIFIC HEAT)HEAT CAPACITY The amount of energy required to raise the temperature of 1 gm of a substance 1 degree Centigrade • Short time for water to heat up… animals and plants would boil in the heat of the sun.. • Not good in Texas

  35. Water can take in/lose lots of heat without changing temperature very much Day/Night Temperature Differences Large on land, small in the ocean

  36. What does this mean? • If we had 3 cookie sheets each 1 cm deep • One filled with water, one with soil and one with sand • The amount of incoming energy that would heat the water 1oC, would heat the soil 1.4oC and the sand 5oC

  37. High Heat of Vaporization Why do we sweat? (evaporation plants & animals) breaking water’s bonds has a cooling effect high energy molecules are lost

  38. To Be or Not to Be..Chemistry of living things. Mass of base elements for a 70 kg (154 lb) person. oxygen 43 kg (61%, Carbon 16 kg (23%, hydrogen 7 kg (10 nitrogen 1.8 kg (2.5 calcium 1.0 kg (1.4%, phosphorus 780 g (1.1%, potassium 140 g (0.20%, sulfur 140 g (0.20% sodium 100 g (0.14% chlorine 95 g (0.14%, magnesium 19 g (0.03%, 0.78 mol) • Elements and compounds that make up living things. • 96% of body mass is made of Oxygen, Hydrogen, carbon, and Nitrogen. • 4% is phosphorus, sulfur, sodium chloride, magnesium, potassium iron, and iodine.

  39. Water transports molecules dissolved in it • Blood, a water-based solution, transports molecules of nutrients and wastes organisms • Nutrientsdissolved in water get transported through plants • Unicellular organisms that live in water absorb needed dissolved substances

  40. Water is Transparent • Water is clear  allows light to pass through it • Aquatic plants can receive sunlight • Light can pass through the eyeball to receptor cells in the back

  41. pH

  42. Acids and Bases Hydrogen ion (H+1) is the basis of the pH scale. Water can form ions. H2O  OH-1 + H+1 hydroxide ion hydrogen ion Greater H+1 concentration --- lower pH (acidic) Lower H+1 concentration --- higher pH (basic)

  43. Acids and Bases

  44. Acid Rain & Global Warming Mini video= Acid Rain & Global Warming

  45. Where is CO2 (aq) seen? Carbonated water CO2 is not very soluble… 1 CO2 in 1000 H2O molecules

  46. Shake (Many bubbles in mixture CO2 under pressure Open can release pressure Bubbles form foam(too big for can) Tap; dislodge bubbles on side; Decrease foam Shaken can; bubbles stick to side

  47. How Do Pressure Cookers Work? Pressure cookers increase the pressure above the water so that water boils at a ________ temperature and cooks food ________ HIGHER QUICKER

  48. PHASE CHANGES Remov i ng Energy Adding energy Evaporating Condensing Subliming (Sublimating) Deposition Melting Freezing

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