1. Properties of Water

2. When a compound is made, normally that compound is neutral because all of the (+) charges have a matching (-) charge.
In a water molecule,
Oxygen:
Hydrogen:
8 Protons
1 Proton
1 Proton
Oxygen:
Hydrogen:
8 electrons
1 electron
1 electron

3. However, they don’t exactly share them evenly
However, they don’t exactly share them evenly. In fact the Oxygen wants the electrons so much, it kind of “hogs” them from the Hydrogen.
This is because of the large amount of (+) charge from the oxygen

4. Because the Oxygen “hogs” the hydrogen electrons, it has a slight negative charge on the oxygen end. (Electrons are negative charged)
This leaves the Hydrogen atoms (with less electron power) with a slight positive charge.

5. This results in what we call a “Polar molecule”
Just like a magnet that has a (+) and a (-) end,
The water molecule has a (+) and a (-) end because the oxygen is hogging the electrons.

6. So that means when water molecules form together
So that means when water molecules form together. They work like magnets. (+)(-) attract each other.
The bonds between the water molecules are called HYDROGEN BONDS. (chemical attractions of polar molecules)

7. Every 1 water molecule can join with 4 others.
These hydrogen bonds are weak bonds, not as strong as Ionic or covalent
Every 1 water molecule can join with 4 others.
Cohesion – an attraction between molecules of the same substance
So water is a very “Cohesive” molecule.

8. Glass is a polar molecule which attracts the water molecules.
Adhesion – attraction between molecules of different substances.
Glass is a polar molecule which attracts the water molecules.
This is why some water stays along the edge of a glass when you pour slowly. You give the water & glass time to form adhesion.

9. Trying to fit as many water drops on a penny shows you both the “cohesive” and “adhesive” properties of water.

10. MIXTURES & SOLUTIONS

11. Chocolate chips & cookie dough
A Mixture is a material composed of 2 or more elements that are physically mixed together, but not chemically combined.
A salt & pepper mixture.
Chocolate chips & cookie dough

12. A solution is a mixture that has the same composition, color, density, and sometimes even taste throughout.
Try adding blue food coloring to a jar, what happens over time is that the coloring evenly mixes all throughout the jar.
It has become a completely homogenous mixture where the molecules of coloring have mixed evenly among the water molecules.

13. The substance being dissolved (the sugar) is called the solute.
To describe a solution you normally say that one substance is dissolved into another.
(like sugar into tea)
The substance being dissolved (the sugar) is called the solute.
The substance that is doing the dissolving (tea) is called a solvent.
Everyone should know what the greatest solvent in the world is.

14. Suspensions – are mixtures of water and non-dissolved material.
Blood is a mixture of water, red blood cells, white blood cells, plasma, and platelets.
Yet, is forms a liquid mixture because all the things above do not react with each other.

15. Hydrophilic molecules are water loving and have an affinity for water.
Hydrophobic molecules will repel water

16. Acid / Base

17. A molecule of water occasionally break into 2 parts.
H2O H OH-
Hydrogen ion
Hydroxide ion
This only occurs about once per 550 million molecules of water.
Water as a whole still remains neutral charges because it even the (+) charged H+ and the (-) charged OH- cancel each other out.

18. The scale runs from 0 to 14, with 7 being the middle or “neutral”
Chemists devise a pH scale to determine how many H+ ions are in a solution. 7 14
The scale runs from 0 to 14, with 7 being the middle or “neutral”
This means at pH 7, the number of H+ ions is equal to the number of OH- ions.

19. Most of you should already know the pH scale
Low pH numbers 1-6 are called Acids,
7 is neutral,
High pH numbers 8-14 are Bases

20. The lower the number, the more “acidic” or the higher the H+ amount is.
Getting more Alkaline
Getting more acidic 7 14
The higher the number, the more “basic” or “alkaline” the higher the OH- amount is.

21. Each number on the pH scale is a factor of 10
Each number on the pH scale is a factor of 10. so for every number you move in a direction, each number means (x10)
If someone added an acid to your pure water… enough to lower it 1pH, how much more H+ ion do you have?
100,000X more
H+ ions 2
10,000X more
H+ ions 3
1000X more
H+ ions 4
100X more
H+ ions 5
10X more
H+ ions 6
10X more
OH- ions 8
100X more
OH- ions 9
1000X more
OH- ions 10
10,000X more
OH- ions 11 7 14

22. Is it more acidic or basic than the original solution?
Problem: Bill had a solution at pH6, adding another chemical to it dropped the pH to pH 3. How many more H+ ions does this new solution have? 7 14 6 3 1
times more H+ ions
Is it more acidic or basic than the original solution?

23. Litmus paper is another indicator of pH.
There is a red and blue litmus paper, but what is important is what color the paper turns when dipped into the solution.
So the solution to the right is?
Blue means Base
acid turns RED

24. Many times you need to know how strong or weak the acid or base is, so on those occasions you can use pH paper like the one to the right.
The paper will turn a different color depending on the amount of H+ ions.

25. PROPERTIES OF ACIDS
Acids have several common properties:
1. Acids taste sour.
- The familiar sour taste in some foods is due to acid. - Still, you should not taste every acid because some acid can cause severe tissue burning.

26. 3. Acids react with indicators
2. Some Acids are corrosive.
- They seem to eat away the metal. Metallic compounds and hydrogen ions form.
3. Acids react with indicators
When an acid reacts with an indicator, you will see a noticeable color change.
This process is called Titration.

27. FOOD ACIDS
Some of the more common acids you see in foods are:
Citric Acid
Lactic Acid
Acetic Acid

28. A very strong hydrochloric acid is found in your stomach which helps dissolve or break down your foods.

29. BASES
You might not be as familiar with bases, but there are some involved in your daily lives…
Egg whites
Baking Powder
Antacids
Soap
Ammonia

30. 3. Bases have a bitter taste.
PROPERTIES OF BASES
1. In the pure, undissolved state, many bases are crystalline in form. (crystals)
2. Bases feel slippery
3. Bases have a bitter taste.
Bitter coffee

31. 4. Bases are corrosive just like acids. (Lye)
5. Bases also react with indicators.
Using Red litmus paper in a base, turns the paper blue
Blue means Base

32. So drinking a lot of Grapefruit juice, since it has a lot of acid in it, will lower my body’s pH level right?
Not really, because inside your body you have dissolved compounds called “Buffers” that maintain your normal body pH around 6.5 to 7.5
This is another way the body maintains “Homeostasis” – a stable internal environment.

33. Specific Heat
Amount of heat that must be absorbed or lost for 1 g to change 1 degree Celsius.
1 gram of water changing 1 degree C = a calorie
Specific heat of ethyl alcohol = . 6 cal/g/C

34. VOCABULARY! Polar Molecule Acid Hydrogen Bonds Base Cohesion Alkaline
Adhesion
Mixture
Solution
Solute
Solvent
Suspension
pH scale
Acid
Base
Alkaline
Buffer