1. Polarity of Water and other Special Properties!

2. I. Facts about water Water is the most common liquid on Earth
Water must be present for life to exist
Water makes up 50 – 90% of living things
Water is 75% of the human body

3. Water is Polar. What is polarity?

4. Matter is made up of electrons (- charge) and protons (+ charge)
Usually, the + and - charges are evenly spread out.

5. However, if the charges are concentrated in different areas...- +
This is now the negative pole
This is now the positive pole
…the object is said to have polarity.

6. …water is slightly polar.
Because the atoms in each molecule of water are not arranged in a straight line... +
This is the positive pole
This is the negative pole -
…water is slightly polar.

7. - + Water obeys the Laws of Electrostatics:
Opposite charges attract each other...

8. The negative sodium is attracted to the positive chlorine
The negative sodium is attracted to the positive chlorine. This is table salt.
Na-
Cl+

9. + +
…while like charges repel.

11. 2H + O  H2O H O H H O + H + -

12. + + -
“Micky Mouse” look

13. + So if anything with a positive charge is put in water... - - -
…the negative poles of water molecules are attracted to it. - + - +

14. Of course, water’s positive pole will be attracted to negative charges.- + - + - - - + - + - +

15. The polarity of water explains why water dissolves more chemicals than any other liquid.

16. Many chemicals are ionic compounds, made of negative and positive ions:- +

17. When these ionic compounds are mixed in water, the water molecules surround both the negative and positive ions, forcing them apart, and dissolving the compound.

18. + - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + +

19. Ionic compounds that dissolve in water include:
Salts
Acids
Bases

20. Some molecules that are not ionic compounds are like water: They are polar also, with a positive and a negative end: + - + - + - + - + - + - + - + -

21. Water molecules will be attracted to the poles of these molecules, separating them from each other, and thus dissolving them. - + - + + - + - - + - + - + - + + - - + - + - + - +

22. Polar compounds that are dissolved by water this way include sugars, amino acids, nucleic acids, alcohols, and many other molecules important to life.
Some molecules are neither ionic, nor polar. Usually, these will not dissolve in water.

23. - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - +

24. Fats and oils, gasoline, kerosene, and waxes are some examples of compounds that will not dissolve in water. These are called NONPOLAR

25. Nonpolar molecules: No negative or positive charges Will not mix with polar substances Exs: oil, wax

26. Water has unique properties because of its polarity.

27. Hydrogen bonds – weakest bond of attraction between hydrogen and other polar molecules

28. Cohesion (“Co-”) – means “sticking together”
Attraction between molecules of the same substance
Caused by hydrogen bonds

29. 3. Adhesion Water molecules sticking to other items with a charge.
ex: capillary action
ex: a meniscus

30. Ex: Water strider insect or floating paperclip on water
4. Surface tension – forms a film- like boundary on the surface of water, can support light objects.
Ex: Water strider insect or floating paperclip on water

31. A fluid that dissolves another material is call a solvent.
Solvent – the dissolving substance, usually a liquid, that makes up most of the solution
The material that is dissolved is called a solute.
Solute – substances that are being dissolved

32. A mixture in which a solute is dissolved in a solvent is called a solution.

33. A Glass of Saltwater Solution – saltwater Solvent – water
Solute - salt

34. A Muddy Stream Solution – stream Solvent – water
Solute – dirt, pollution, chemicals

35. A Cup of Coffee Solution – coffee Solvent – water
Solute – coffee, sugar, cream, milk

36. Substances that do NOT dissolve in a solvent, are said to be Insoluble.

37. Water is the best solvent known
Water is the best solvent known. It will dissolve more substances than any other fluid.

38. Water - Density

39. Density – the ratio of mass of matter to its volume.
What can you infer about the density
of these liquids?
O O O O O O
Oil
O O O O O O O O O O O O
Water
O O O O O O O O O O O O O O O O O O O O O O
Soap
oooooooooooooooooooooooooooooooooooooooooooo
Syrup

40. The 3 states of water

41. Solid – molecules expand to form a 6 sided crystal

42. Liquid – molecules contract

43. Gas – molecules separate; hydrogen bonds are broken

44. Changes in the state of water are
due to the addition or removal of
Heat.
Solid absorbs heat Liquid absorbs heat Gas
Solid releases heat Liquid releases heat Gas

45. The Density of Water

46. Least dense A. gas
B. solid
Most dense C. liquid

47. The unique properties of water density
Why oceans and lakes don’t freeze solid
Facts:
Water is densest at 4o C
Water contracts as it cools to 4o C
As water goes from 4o C to freezing (0o C) it expands to become less dense than liquid
As water molecules bond together to form ice, they release heat

48. .

49. Lab book Entry Date: 9-15-06 Title: Properties of Water Table of Contents: add it in
What are the ingredients in the following solutions that act as the solute and solvent?
a. Lemonade
b. 409 Cleaner

50. 2.Why does the polarity of water make it such a good solvent
3. Draw 5 water molecules as they would line up next to each other. Show the partial charges on each atom.

51. 4. Explain why fish and other aquatic
life do not die when the top of a
pond is frozen in winter.
Less dense ice forms heat released
Cold water sinks
4o C at bottom
Thermal inversion