1. Water & pH
Packet #7
Chapter #2

2. Introduction Most abundant liquid in the world
Makes up at least half of all living organisms and up to 95% of some species.
75% of earth is submerged in water
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3. The Water Molecule
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4. Properties of Water
Density

5. Density H2O (l) is more dense than H2O (s)
Water freezes from top downward allowing ice to form at the top
Ice at top can insulate the warmer water below that layer from colder temperatures above
Prevents large bodies of water from freezing solid and allowing the survival of aquatic organisms
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6. Properties of Water
Cohesion and Adhesion

7. Cohesion & Adhesion Cohesion
Attraction of molecules of the same substance.
The hydrogen bonding allows water to be cohesive
Causes individual water molecules on the top to be drawn inward allowing for the appearance a smooth surface.

8. Cohesion & Adhesion Adhesion
Attraction of molecules of different substances.
Example of water in a graduated cylinder.

9. Properties of Water
Specific Heat

10. Specific Heat
Specific heat is defined as the amount of heat, measured in calories, required to raise the temperature of one gram of a substance by one Celsius degree.
Water has a very high specific heat
It takes a long time for water to heat up.

11. Major Properties of Water
Density
Cohesion
Adhesion
High Specific Heat

12. Other Important Water Fact(s)

13. Solubility
Water makes an excellent solvent and makes up most solutions
Any solution that contains water is called an aqueous solution.

14. Solubility Water is a versatile solvent due to its polarity
Can form an aqueous solution.
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15. Other Important Points II
Hydrophilic substance
Water loving
Has an affinity for water
Hydrophobic substance
Water hating
Does not have an affinity for water
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16. pH

17. pH
The pH scale will tell us how willing a compound is in giving hydrogen ions (H+)
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18. pH—Acid & Base Reaction
Bronsted-Lowry Acid
A substance that donates a hydrogen ion (H+)
An acidic solution has a higher concentration of H+ than pure water and have pH values below 7
Bronsted-Lowry Base
A substance that accepts a hydrogen ion (H+)
A basic, or alkaline solution, contain lower concentrations of H+ than pure water and have pH values above 7.
Using H2O (Base) and HCl (Acid)
H2O = Water
HCl = Hydrochloric Acid
The hydrogen in the compound HCl donates/gives it’s electron to Cl
Hydrogen will have a positive charge because it is missing an electron and Chlorine will have a negative charge because it has gained an electron (These are called ions; H+ and Cl-)
The oxygen atom, located in the water molecule and is electronegative, decides to give the Hydrogen ion an electron
Hydrogen attaches to H2O to make H3O+
It has a positive charge because the Hydrogen ion attached missing an electron
H3O+ is called the Hydronium ion
In the end as a result of the Acid-Base Reaction, the end produces are H3O+ and Cl-
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19. pH Scale
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20. Review

21. Water is a polar substance
Review
Water & pH
Properties of Water
Density
Cohesion
Adhesion
Specific Heat
Solubility
Mixtures
Solutions
Aqueous Solutions pH
Acid
Donates hydrogen ions
Base
Accepts hydrogen ions
pH Scale
Acids
pH < 7
Neutral pH
pH of 7
Bases
pH >7
Water is a polar substance