1. Primarily due to polarity
Properties of Water
Primarily due to polarity

2. Video1 “Properties of water” – 4 ½ min
Why is ice less dense than water?
How does ice floating on water impact the survival of the living organisms
Draw the water structure.
How does the term “polar” describe the water molecule?
What is the intermolecular force between water molecules called?
Explain surface tension in water

3. Intro to water Molecule two hydrogen atoms and one oxygen atom
v-shaped triangular molecule
hydrogen bonds
Polarity
properties

4. Intro to Water
Water is a molecule made up of two hydrogen atoms and one oxygen atom. It has the formula H2O. When oxygen and hydrogen combine (H-O-H) they form a v-shaped triangular molecule. While water molecules are electrically neutral, the oxygen atom holds a small negative charge and the two hydrogen atoms hold small positive charges. Water molecules are attracted to each other, creating hydrogen bonds. These bonds determine almost every physical property of water and many of its chemical properties too. Scientists believe this unusual electrical balancing, called polarity, gives water some of its remarkable properties

5. Terms to know by the end of the lesson Video 2
Polarity
Hydrogen bond
Cohesion
Adhesion
Surface tension
Capillary action
Specific heat

6. Water Physical Properties (review)
At what temperature in Celsius does water start boiling?
At what temperature in Celsius does water start melting?
At what temperature in Celsius does water start freezing?
What is the density of water?

7. Water has a high specific heat capacity
Water has the ability to absorb a lot of heat with a relatively small increase in temperature
Water has one of the highest specific heat capacity
This allows marine organisms to avoid drastic temperature fluctuations in the seawater.
This allows orchards grown on the coast to survive hot summers and severe winters.

8. Water “acts” like a magnet Video 4

9. Lewis e-dot structure of water molecule 2 lone pairs – accounts for its bent shape

10. Water molecule is V-shaped - BENT

11. Thinking critically
Videos5&6
If matter expands when heated, and contracts when cooled, why does ice expand (increase in volume) when water freezes?

12. When water freezes, it goes from a mixed up liquid state where all these V's are just sliding around each other, to an ordered crystalline solid state where all the V's have to connect with each other in nice orderly solid shapes.

13. The closest and easiest solid crystal shape for something that exists as a degree V is a hexagonal (really tetrahedral in 3D) crystal. Think of it as a flat hexagonal snowflake shape, but it really goes in three dimensions. The water molecules want to do this because to them it "feels" nicer--that is: they feel less strain and they can get into a lower energy state by getting into this nice orderly hexagonal crystal.

14. video clip “Why ice float “
Critical Thinking: If ice were more dense than liquid water, how would this impact the survival of the marine life? (The floating layer of ice insulates the liquid water below, so that it wouldn’t freeze – this makes the ocean environment to easier to live in)

16. H2O is Polar As we know – water is neutral
(equal number of e- & p+ = zero Net Charge)
But because the O atom is more electronegative than the H atoms – electrons spend more of their time nearer the oxygen. (O atom attracts more than its “fair” share” of electrons).
This gives water a slight overall charge.
The oxygen end “acts” negative.
The hydrogen end “acts” positive.
This charge is called polarity

17. Oxygen “pulls” closer to it creating positive and negative sides of the polar molecule.

18. Water is Polar

20. Blast from the past: What is electronegativity?
How does it change across a period?
Down a group?
What is the most electronegative element on the PT?
Least electronegative?
Which of the two elements, S or N, has a greater ability to attract another atom’s valence electrons?

22. I am more electronegative than selenium, but less electronegative than chlorine? Who am I?

23. Electronegativity values-how to determine if a bond is polar or not-polar Oxygen – 3.44 Hydrogen – 2.20 Difference in values– 1.24 (polar bond) The bond is polar if the difference is between Non-polar = or less than 0.5 Ionic = or greater than 1.7

24. Other examples of polar molecules (no lone pairs):
Carbon is more electronegative
Oxygen is more electronegative

25. Non-polar molecule (lone pair):

26. Water is a universal solvent
Water can dissolve more substances than any other solvent.
Give examples of substances that water can dissolve.
The dissolving power of water is very important for life on Earth. Wherever water goes, it carries dissolved chemicals, minerals, and nutrients that are used to support living things.
Water is a universal solvent

28. “Like dissolves like” (due to its polarity)
Water (polar) + Styrofoam (non-polar)
Acetone (nonpolar) + Styrofoam (non-polar)
“Like dissolves like” (due to its polarity)

29. Polar Bonding Polarity really does allow bonding
They are hydrogen bonds and they are weak
They last for fractions of a second
Continuously break and reform
video clip “Water molecule Part 1” - bonds breaking and reforming
Polar Bonding

30. Hydrogen Bonds (Formed between a highly Electronegative atom of a polar molecule and a hydrogen (O-H)
Opposites attract

31. This model to show the attraction between H and O – hydrogen bonding

32. Forces due to polarity
Cohesion
Adhesion

33. Cohesion (water is sticky)
Attraction between particles of the same substance ( why water is attracted to itself)
Results in Surface tension (a measure of the strength of water’s surface)
Produces a surface film on water that allows insects to walk on the surface of water

34. Inside a drop of water polar water molecules attract to each other in a random fashion
At the surface of the drop, water does not attract to the air
A unified layer of molecules at the surface creates surface tension
There the water behaves like an flexible sheet allowing denser objects to “sit” on the surface.
Surface Tension

35. Surface tension (cohesion)
Can be seen as water
droplets form
Helps insects walk across
water
Surface tension (cohesion)

36. Adhesion Attraction between two different substances.
Water will form hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton
Adhesion Causes Capillary Action, which gives water the ability to “climb” structures.

37. Adhesion Form spheres & hold onto plant leaves
Can be seen as water droplets form on the spider web (another polar surface)
Form spheres & hold onto plant leaves
Adhesion

38. Capillary action
We know that gravity is ALWAYS pulling on objects with mass
Yet water can move up a paper towel with relative ease – How can this happen?
Because the positive and negative charges in the paper attract the polar water molecules (adhesion)
This property of adhesion is called capillary action.

39. Warm up: 2/25/13
Explain the following water properties in both words and drawings(2 min)
Polarity-
Like dissolves like-
Heat capacity
Water acts as a magnet-
Trade notebooks with your partner write one constructive comment in your partner’s notebook. Hand them back their notebook( 1min)

40. How do heterogeneous and homogeneous mixtures differ?(Left Side)
Salt solution and Oil in water
2 min - Quick Write: Based on your prior knowledge about mixtures, explain why a salt solution is classified as a homogeneous mixture and a mixture of oil and water is said to be a heterogeneous mixture.
White boards activity:
Homo- or Hetero - ?
COKE
AIR
STEEL
A JAR OF PENNIES
Coke (mixture of CO2 gas, water, sugar, caramel color, food flavorings)
Air (mixture of O2 and N2)
Steel (alloy – mixture of Fe and C)
A jar of pennies and nickels
Notes

41. By the end of the day you will know:
Solute
Solvent
Solution
Soluble
Insoluble
Immiscible
Separation
Solvation
Factors affecting the rate of dissolution
Next notes…

42. Complete the sentences.
When you put salt into water it______. The salt dissolves because it is ________in the water. The substance which dissolves is called the ______. The substance that does the dissolving is called the _______. When something dissolves you get a _______.
Water is a ________. Salt is a ________.
When a substance does not dissolve it is________
Dissolution of salt in water
water.jsp

43. Animation - Dissolution of an Ionic compound (results in dissociation) and a covalent compound (no dissociation) wf
Animation – Strong electrolyte (complete dissociation into ions) – many ionic compounds – conduct electricity - (+ strong acids and bases – will cover in more detail in Bundle 11)
Animation – Weak electrolyte (partial dissociation) – weak acids and bases (if a conductivity meter is used - light is not as bright (dim) compared to a strong electrolyte)
Animation – Non-electrolyte ( no dissociation)  - no disruption of its molecular (covalent) structure – does not conduct electricity

44. Checking for understanding
The dissolved components of ionic and covalent compounds are:
All ions
Ions for ionic and molecules for covalent compounds
Ions for covalent and molecules for ionic

45. The dissolution of KNO3 and C3H6O (acetone) in water occurs:
Molecules by molecules for both KNO3 and C3H6O
Ion by ion for KNO3 and molecule by molecule for C3H6O
Ion by ion for C3H6O and molecule by molecule for KNO3

46. Based on your observations of the dissolution process on the animation, how do you think substances get dissolved?
Each solvent molecules gets separated from other molecules and is surrounded by ions in ionic substances or molecules in covalent substances
Each ion in covalent substances and each molecule in ionic substances gets separated from other molecules or ions and is surrounded by solvent molecules
Each ion in ionic substances and each molecule in covalent substances gets separated from other molecules or ions and is surrounded by solvent molecules.

47. For the following reaction
Warm up 2/25/13
For the following reaction
identify the products as insoluble or soluble.
Na2CO3 + CaCl2  CaCO3 + 2NaCl
Classify the type of reaction
Activity
Sketch the process of dissolution of calcium chloride. Find a partner - compare each other’s drawings – make corrections if needed(4min)

48. Factors that Affect the Rate of Dissolution
Pre-assessment:
If you wanted to dissolve a substance in water as quickly as possible what could you do?

49. The three methods to increase the rate of dissolving for a solid are?
Heat it!
Crush it!
Stir it!

50. How can you achieve the following:
Increased number of collisions between solvent and solute
Agitation
Increased surface area
Increased kinetic energy

51. Notes –Solubility
the amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure (for gases)
grams of solute per grams of solvent
grams of solute per 100ml of solvent

52. Example: at 25. 0 0C, the solubility of sodium chloride is 35
Example: at C, the solubility of sodium chloride is 35.0 grams per 100 ml of water.
You can dissolve up to 35.0 grams of sodium chloride in 100 ml of water.
If you add more than 35.0 grams the solid will simply not dissolve.

53. Based on solubility we can have three types of solutions:
Unsaturated – a solution that could dissolve MORE solute at a specific temperature
 Saturated – a solution that contains the MAX amount of solute that can dissolve at a specific temp (stable)
Visual evidence: a small quantity of un-dissolved solute remains in solution
Supersaturated – a solution that contains more dissolved solute than a saturated solution. (Prepared by heating the solvent, adding solute, and cooling slowly – very unstable)
DEMO. Supersaturated solution of Sodium Acetate

54. Solubility Graph Grams of solute per 100 g of water NaClO3 KBr NaCl
Grams solute/100 g H2O
NaClO3
KNO3
KBr
NaCl
Temperature
Solubility Graph
Grams of solute per 100 g of water

55. How much solute will dissolve?
A solubility curve shows the amount of each solute that will dissolve in 100g H20 at each temperature.
Saturated is on the line.
Unsaturated is below the line.
Supersaturated is above the line.
Grams solute/100 g H2O
NaClO3
KNO3
KBr
NaCl
Temperature

56. How much solute will dissolve?
A solubility curve shows the amount of each solute that will dissolve in 100g H20 at each temperature.
Saturated is on the line.
Unsaturated is below the line.
Supersaturated is above the line.
Saturated
Grams solute/100 g H2O

57. What is the solubility of KNO3 at 60 oC in 200 g of H2O?
How many grams of KBr can dissolve in 300 gr of H2O at 100 oC?
Grams solute/100 g H2O
NaClO3
KNO3
KBr
NaCl
Temperature

58. How much solute will dissolve?
Grams solute/100 g H2O
Unsaturated

59. How much NaClO3 would you have to add to 100 g of water at 50oC to make a saturated solution?
Look at the intersection.
Grams solute/100 g H2O
Approx. 140 – 142 g

60. Mini Lab: WHAT FACTORS INFLUENCE DISSOLUTION
Surface Area (Solid Solute)
1) Record the time 1 sugar cube needs to dissolve in 200 ml of tap water. ______
2) Crush 1 sugar cube in the mortar & pestle. Record the time the crushed sugar cube needs to dissolve in 200 ml of tap water. _____________
Temperature (Solid Solute)
3) Obtain 200 ml of warm water from the front lab table. Color one side of the sugar cube with a Vis-A-Vis marker. Add the sugar cube to the warm water & record the time the cube needs to dissolve. _____________
 4) Obtain 200 ml of cold water from the front lab table. Color one side of the sugar cube with a Vis-A-Vis marker. Add the sugar cube to the cold water & record the time the cube needs to dissolve.___________
Stirring (Solid Solute)
5) Place 1 sugar cube in 200 ml of tap water. Record the time the cube needs to dissolve without stirring.______________
6) Place 1 sugar cube in 200 ml of tap water. Record the time the cube needs to dissolve while you stir the solution._____________

61. Homework: Lab analysis questions
1) How do you increase the surface area of a solid?
2) How is surface area of a solid solute related to dissolution? WHY?
3) How is temperature related to the dissolution of a solid solute? WHY?
4) What effect does stirring have on the dissolution of a solid solute? WHY?

62. Checking for understanding

63. The Great Soda Mystery!
What is the difference between the hot soda and cold soda? Why?
As temperature _______,
solubility of a gas ______.
3. Does pressure affect the amount of gas in the soda? How?
4. As pressure _____, solubility of gases ______.

64. In general solubility of solids increases with increasing temperature.
Temperature Effects
In general solubility of solids increases with increasing temperature.
Solubility of gases in water decreases with increasing temperature.
Thermal Pollution: of lakes and streams leads to a decrease in oxygen content of the water.
Warmer waters is less dense and is found at the surface where the oxygen must dissolve to reach water at lower depths.

65. Solubility of Gases
When something is heated it will favor the gas phase, therefore, heating solutions with gaseous solutes will decrease the solubility.
For example, carbonated water can dissolve more carbon dioxide at lower temperatures. The following is a solubility curve for gases

66. Solubility of gases versus solubility of solids

67. Pressure
Pressure has little effect on the solubility of liquids or solids in liquid solvents.(can’t not be compressed)
The solubility of a gas in a liquid solvent INCREASES when pressure increases. The pressure holds the solute (CO2 gas) in the solution.

68. Electrolyte - An ionic compoud whose aqueous solution conducts electricity. (Dissolved in water, the positive and negative ions are free to move (mobile ions) and can conduct elect.)
Solid ionic compounds can’t conduct electricity (ions are present but they are NOT mobile)
Strong (HCl, KCl) – completely ionize in water.
Weak (vinegar – acetic acid) – partially ionize in water
Ex: NaCl almost completely ionizes in solution and produces positive and negative ions, which will conduct electricity. Electrolytes can be found in sports drinks (ex. Gatorade) – maintain homeostasis.

69. Warm up 3/5/13 1) When the attractive forces within the particles of a solid substance are weaker than the attractive forces between the solid particles and its liquid solvent, what will happen to the solid substance? Draw a picture representing the above scenario.

70. Exit Pass- What do all of the following have in common?
KCl(aq) NaCl(aq) AgNO3(aq)
NaOH(aq) HCl(aq)
They are all homogeneous mixtures= solutions
Which is the solute and solvent in each one?

71. Concentration of Solutions How would you describe the concentration of the Kool-Aid solutions? How do you know which solution contains more or less solute?

72. Concentration – a measure of how much solute is dissolved in a specific amount of solvent.
Concentration may be described qualitatively using the words:
1. Concentrated- contains a LARGE amount of solute
2. Dilute – contains a SMALL amount of solute

73. Although qualitative descriptions of concentration can be useful, solutions are more often described quantitatively. One of the commonly used quantitative descriptions is MOLARITY.
B. Calculating Concentration
1. Molarity (M) – The # of moles of SOLUTE dissolved per LITER of solution.
M = moles solute
L of solution
a. Ex: An IV solution contains 5.10 g of glucose (C6H12O6) in ml of solution. What is the molarity of the solution?
b. Ex: How many grams of Na2SO4 would be dissolved in 1.5L of a .24M solution of Na2SO4?

74. In the laboratory, you may use concentrated solutions of standard molarities called stock solutions. For example, concentrated hydrochloric acid (HCl) is 12M. You would rarely use this concentration in a lab. How would you prepare a LESS CONCENTRATED (dilute) solution? You can prepare a less concentrated solution by taking a concentrated solution (stock solution) and diluting it with solvent

75. M1V1 = M2V2