Water Bonding Water has unusual properties

1. Water BondingWater has unusual properties

2. Polar Covalent Bonding of Water:Unequal sharing of electrons(intramolecular forces) OR H O Means partially + Means partially - H

4. Hydrogen Bonds hydrogen bond = is the attractive force between the hydrogenattached to an electronegative atom (tendency to attract electrons) of another molecule (usually O, N, F) Hydrogen Bonding Dance (1 min)

5. Youtube Polarity and Hydrogen Bonding • (3:52)

6. Water Molecules • Can bond to fourother water molecules • H+ end attracts the O-ends

7. Polarity of Water helps H-bonds form • Uneven sharing of electrons • Between slightly (+) H atom to a slightly (-) atom of a different molecule • H-bonding of water • H- Bonding and polarity

8. Hydrogen Bonds between Water Molecules • Weaker than covalent and ionic bonds • Stronger than van der Waals

9. Cohesion Like in drops • Water is attracted to other water molecules (similar polar molecules) • H-bonding between water molecules hold them together

10. Cohesion is why a waterfall, a stream, a water drop forms

11. Adhesion Strong adhesion to glass • Attraction of unlike substances • EX: water to the sides of a glass tube • Drop to leaf Not so much with plastic

12. Adhesion or Cohesion?

13. Surface Tension -the attraction of molecules to each other (cohesion) on a liquid's surface pull inward (due to H-bonds) to create a “film” A screen showing surface tension youtube Water molecules pull in all direction not on the surface

14. Surface Tension allows a Pennyor Paper Clip to float?Surface Tension and Capillary Action?? - YouTube Surface tension is responsible for the shape of water droplets H-bonds pull in water to create a “film”

15. Water Strider • Jesus Christ Lizard (natl geo) (1.25 mins) • Can stand on top of water • Water Strider on Pond Surface (44 secs) See indentations of water strider’s feet in water.

16. High Specific Heat • = the amount of heat per unit mass required to raise the temperature by one degree Celsius. • The specific heat of water is higher than any other common substance. WHY? • Have to break/form those H-bonds.

17. Phases of Water • Describe how the molecules change (speed and spacing between molecules) as the temperature changes. • Water Phase Change Animation (keep clicking on the “increase heat”) • Did the water molecules break apart or did just the spacing between them change?

18. Note the spacing between the water molecules

19. Heat of fusion = needed to melt ice (solid to liquid)Heat of vaporization = needed to evaporate to water vapor (liquid to gas) • (note how long it takes to break the H-bonds)

20. Water has High Heat of Vaporization • Takes a high temperature to evaporate, or boil water • Need to break those H-bonds

21. Water has High Heat of Fusion(Amount of heat to go from solid to liquid) • Takes a low temperature to freeze water (loses at lot of heat) • Those H-bonds must form

22. Look at the spacing and speed of molecules in each phase • Vision Learning (scroll down to Liquid Water and H-bonding and to Ice and H-bonding)

23. Heat Total amount of energy of the atoms/molecules Temperature A number of the average speed of molecules What’s the difference between… Which has more heat…10 mL of 50o C water or 100 mL of 50oC water?

24. Going from water vapor to liquid to solid ice As heat is released the attraction between the molecules (intermolecular forces) increases Going from ice to liquid water to water vapor As heat is taken in the attraction between the molecules (intermolecular forces) decreases SOLID ICE LIQUID WATER WATER VAPOR

25. Evaporative Cooling • The water of the surface of the skin absorbs heat to change water from liquid to gas. You feel cooler.

26. Water has High Specific Heat • Takes a lot of heat to raise the temperature of water 1oC(break the H-bonds) • This is why coastal areas have milder climates.

27. Kelley’s Island • Has the same weather as northern Ohio except… • “The still warm lake keeps us warmer in the fall, but the still cool lake gives us cold breezes in the spring.”

28. Water expands upon freezing • If water worked like other liquids, then there would be no such thing as an ice berg, the ice cubes in your soft drink would sink to the bottom of the glass, and pondswould freeze from the bottom up!

29. Ice forms an Open lattice • Below 4oC (H-bonds form) • Ice floats • H-bonds are more stable in the solid form of water H-bonds

30. Ice Expands and is Less Dense than Liquid Water 4 oC Liquid Solid

31. Water is the “Universal Solvent” • Means it can dissolve a lot of substances due to its polarity • Dissolving NaCl in water movie • dissolve animation

32. Water is the Universal Solvent • What types of compounds are good at dissolving? • Polar • Ionic • WHY? • Opposite charges attract • Remember: Likes dissolve likes: Polar into polar/nonpolar into nonpolar

33. Aqueous Solution • Means a solution in which water is the solvent • Ag+(aq) + Cl-(aq) → AgCl(s) • EXAMPLES: blood, Coke, Pepsi, urine, Tea, coffee

34. Mixtures-Solutions-Suspensions • Mixtures: 2 or more elements physically mixed (NOT CHEMICALLY BONDED) • A. Solutions: type of mixture with evenly distributed ions throughout • B. Suspensions: Mixture of water andundissolved material keeping the small materials suspended

35. Can you identify: Mixtures-Solutions-Suspensions? Oil and Water Sand and Salt

36. What is the difference?

37. What’s the difference between… • Mixtures, solutions, suspensions, and COMPOUNDS?COMPOUNDS ARE CHEMICALLY JOINED…the others are physically mixed.

38. SOLUTIONS • When one substance dissolves another substance. • SOLVENT + SOLUTE = SOLUTION • Solvent=material doing the dissolving (surrounding the ions) • Solute=what is being dissolved

39. Salt Solution Which is the solvent? Which is the solute? Water is solvent. Salt is the solute.

40. Amphipathic • Bipolar • A molecule that is water-loving (polar) at one end and water-hating (non-polar, like oils) at the other end

41. How does detergent work? Soap has a water-loving (hydrophilic) and a water-hating end (hydrophobic). Soap (hydrophobic end) attaches to the oil and also to the water (hydrophilic end) to wash away the oil. (animation, wait for it) How Soap Works

42. Capillary Action • Capillary action – the narrower the tube the higher the water rises • Adhesion - of water to tube • Cohesion-water to water (column of water) Meniscus-water creeps up the sides of the glass tube

43. Note size of tube diameter and the height the liquid rises

44. Capillary Actionor Capillarity • The thinner the straw or tube the higher up capillary action will pull the water. • Flowers and Food Coloring • Water transport in xylem tubes youtube • surface tension and capillary action youtube

45. Transpiration • Loss of water vapor from parts of plants, especially in leaves • ?Transpiration?? - YouTube

46. Explain how each of these allow water to pull up a plant? • Cohesion ?Transpiration?? - YouTube • Adhesion • Transpiration • Can you explain what is going on in this video? • ?Flowers and Food Color Time Lapse?? - YouTube

47. Capillarity in Plants • Surface Tension and Capillarity You Tube Video • Water Transport in Plants

48. Solutions • A SOLUTE is the substance to be dissolved (sugar). • The SOLVENT is the one doing the dissolving (water).

49. What is the difference?

50. SALT SOLUTION • Animation of Salt Dissolving in Water • Dissolve Another Nice Animation • When water is the solvent, the solution is called an aqueous solution.