1. Water

2. Earth the Water Planet

3. Earth the Water Planet

4. Special Properties of Water
Universal Solvent
Transparency
Three Physical Phases
Density and Temperature
High Specific Heat
High Heat of Vaporization
Low Compressibility
“Stickiness” of Water Molecules
Viscosity

5. Polarity of Water Molecules

6. Hydrogen Bonding Between Water Molecules

9. Hydrogen Bonding Between Different Molecules

10. Universal Solvent

11. Universal Solvent
Solution = A liquid in which two or more substances are homogeneously mixed.
Solvent = Fluid portion of a solution into which other substances are dissolved.
Solute = A substance that is dissolved into a solvent to produce a solution.

12. NaCl (sodium chloride) Dissolving Into Water
Universal Solvent
NaCl (sodium chloride) Dissolving Into Water

13. NaCl Dissolving Into Water
Universal Solvent
NaCl Dissolving Into Water

14. NaCl Dissolving Into Water
Universal Solvent
NaCl Dissolving Into Water

15. Protein Dissolving Into Water
Universal Solvent
Protein Dissolving Into Water

16. Solubility of Solids
In general, the solubility of solids increases with increases in temperature.

17. Solubility of Gases
In general, the solubility of gases decrease with increases in temperature.

18. Importance to Living Things
Water is the solvent in which most of the chemistry of life takes place.

19. Transparency

20. Electromagnetic Radiation

21. Electromagnetic Radiation

22. Light Intensity and Depth in the Ocean

23. Spectral Characteristics of Light with Depth

24. Importance to Living Things
Aquatic plants are able to live and photosynthesize beneath the surface of the water.
Animals are able to see below the surface of the water.
Changing spectral distribution of light with depth influences physiology and behavior of living things.

25. Three Phases of Water
solid
liquid
gas

26. Three Phases of Water
solid
liquid
gas

27. Ice vs Liquid Water
hydrogen bonds
ice
liquid

28. Melting and Boiling Temperatures of Water

29. Colligative Properties
Dissolved solids increase the boiling point and decrease the freezing point.

30. Importance to Living Things
Water exists in all three phases at temperatures found on Earth.
If water behaved like substances with similar molecular weight, water would exist only as a gas and it’s likely that the Earth’s gravity wouldn’t retain water.

31. Density and Temperature
Above 4°C the density of liquid water decreases as the temperature increases.
As the temperature is decreased from 4°C to 0°C, the density decreases.
Water exhibits a density maximum of 1.0 grams/milliliter (g/mL) at 4°C.
Ice is less dense than water.

32. Density Behavior of Water

33. Specific Gravity

34. Importance to Living Things
Ice floats on top of liquid water.
If ice were more dense than liquid water, then ice would sink, leading to a freezing-over of many lakes and streams.

35. Ice Floats!

36. High Specific Heat
1.0 calories of absorbed heat energy will raise the temperature of 1.0 gram of water by 1.0°C.

37. Importance to Living Things
Water can buffer the environment and living things against extreme changes in temperature.

38. High Heat of Vaporization
At 25°C, 1.0 gram of water must absorb 580 calories of heat energy in order to be converted from a liquid to a gas.

39. Importance to Living Things
Water vapor in the atmosphere moderates the Earth’s climate.
Living things may moderate their body temperatures via evaporation of water from their surfaces (evaporative cooling).

40. Low Compressibility
Liquid water does not compress significantly into a smaller volume.

41. Importance to Living Things
Water can provide shape and form to a living thing (hydrostatic skeleton). For some organisms a hydrostatic skeleton may facilitate movement.
Aquatic organisms may swim.

42. Low Compressibility

43. “Stickiness” of Water Molecules
Cohesion
Adhesion
Surface Tension

44. Cohesion
The binding together of like molecules; the binding together of water molecules to each other via hydrogen bonds.

45. Adhesion
The binding together of different molecules; the binding of water molecules to other substances via hydrogen bonds.

46. Cohesion + Adhesion
Capillarity

47. Importance to Living Things
Cohesion and Adhesion in Water Transport in a Plant

48. Surface Tension

49. Importance to Living Things

50. Resistance of a Fluid to Flow
Viscosity
Resistance of a Fluid to Flow

51. Colloids and Suspensions

52. Importance to Living Things
The viscosity of water may be a significant force resisting movement in very tiny aquatic organisms.
The viscosity of water retards the rate at which small suspended particles may settle through it.
The viscosity of water may influence transport of fluids throughout an organism.

53. Decomposition of Water
H2O  H+ + OH-
1 in 107 water molecules will decompose this way in a container of pure water ( [H+] = 10-7 M).
Note that the concentration of H+ is equal to the concentration of OH-)

54. pH of pure water = -log[10-7] = 7
Definition of pH
pH = -log[H+]
pH of pure water = -log[10-7] = 7

55. Acids
Add excess H+ to the solution such that [H+] > [OH-].
HCl  H+ + Cl-

56. Bases
Remove H+ from the solution such that [H+] < [OH-].
NaOH  Na+ + OH-

57. pH Scale Type of Solution pH Value Neutral 7 Acidic <7
Basic (alkaline) >7
Type of Solution
pH Value

58. pH Scale

59. Buffers
Chemicals that minimize changes in the pH of a solution.

60. Importance to Living Things
Enzymes (enzymes regulate chemical pathways in cells and tissues) and other proteins of living things are pH-sensitive.
The pH of physiological solutions may influence chemical equilibria.

61. Water