1. Chemical Reactions
Properties of Water
Solutions
Acids, Bases, and pH

2. PROPERTIES OF WATER
The water molecule is a great example of the uneven sharing of electrons
The preceding creates some of the unique properties of water like…

3. PROPERTIES OF WATER Water molecules are unique because…
Surface tension
High boiling point and low freezing point
Density of ice vs. water

4. PROPERTIES OF WATER HYDROGEN BONDING
A force of attraction between molecules
Instead of atoms attracting other atoms or molecules, the molecule attracts neighboring molecules
Always involves hydrogen attracted to
Fluorine
Oxygen
Nitrogen

5. PROPERTIES OF WATER Adhesion and Cohesion
Water is attracted to other water. This is called cohesion.
Water can also be attracted to other materials. This is called adhesion.
The oxygen end of water has a negative charge and the hydrogen end has a positive charge. The hydrogens of one water molecule are attracted to the oxygen from other water molecules.
This attractive force is what gives water its cohesive and adhesive properties.

6. SOLUTIONS Solution - a homogenous mixture.
Homogenous - a mixture that is completely uniform in composition; its components are not readily distinguished.
Is a dispersion of ultimate-sized (molecules, atoms, ions) particles of solute in solvent.

7. SOLUTIONS Cannot be separated into solute and solvent by filtration.
Is clear (transparent), but may be colorless or colored.
Acts as though it is in a single phase.

8. SOLUTIONS Solute – dissolved particles in solution.
Solvent – the dissolving medium in a solution.

9. SOLUTIONS
The solute is the substance, which is being dispersed by the dispersing agent, the solvent. The solute is generally in smaller quantity but in solid/liquid solutions, the solid is generally considered to be the solute regardless of quantities.

10. SOLUTIONS
Both solute and solvent may be solid, liquid, or gas. They may be paired a variety of combinations.
Types of solutions
Example
Solute
Solvent
solid in liquid
salt water
salt
water
gas in liquid
ammonia water
ammonia
gas in gas
air
oxygen
nitrogen
solid in solid
brass alloy
Zinc
copper
liquid in liquid
alcohol solution
alcohol

11. SOLUTIONS
In order for a solute and solvent to disperse in one another there must be attractive forces, which are similar to in strength to those, which existed between the solute particles and also between the solvent particles. For this reason ionic (NaCl) or polar solutes (hydrogen Chloride) will dissolve readily in water, a polar solvent.
Non-polar solutes such as iodine and hydrocarbon compounds dissolve much more readily in each other than in water.
Solubility is a term used to describe the maximum amount of solute, which can dissolve in a given amount of a specific solvent at a given temperature and pressure.

12. SOLUTIONS
“Likes Dissolve Likes.” Useful method for describing the combinations of solutes/solvents which will dissolve readily.
-Miscible - describes liquids that dissolve in each other.
-Immiscible – describes liquids that are insoluble in one another: oil and water are immiscible.

13. SOLUTIONS
Often water will not mix with molecular liquids like oil. We say that the two liquids are not miscible. They do not mix together or dissolve - they form two separate layers. They have to be shaken up to get them to mix for just a short time.
Picture: Oil and water don't mix. They are immiscible. They form two separate layers. Shaking them will mix them for a short time.

14. SOLUTIONS
Saturation amount (solubility) is related to solvent and solute, (polar, non-polar, ionic) temperature, and (in cases where the solute is a gas) pressure.
-Dilute – a solution that contains a small amount of solute.
-Concentrated – a solution containing a large amount of solute.

15. SOLUTIONS
Unsaturated - a solution that contains less solute than a saturated solution at a given temperature and pressure.
Saturated – a solution containing the maximum amount of solute for a given amount of solvent at constant temperature and pressure; an equilibrium exists between undissolved solute and ions in solution.
Supersaturated - a solution that contains more solute that it can theoretically hold at a given temperature; excess solute precipitates if a seed crystal is added.

16. SOLUTIONS
Colligative Property – a property of a solution that depends only on the number of solute particles; boiling point elevation, freezing-point depression, and vapor pressure lowering are colligative properties.

17. Acids and Bases
Water dissociates into hydrogen ions (H+) and hydroxide ions (OH-). They ions then re-associate back into water: it’s a constant back-and-forth process, with an equilibrium between the H2O form and the H+ and OH- forms.
Acids produce H+ ions when dissolved in water
Bases absorb H+ ions when dissolved in water.
Water is neutral, neither acid nor base, because it always has equal numbers of H+ ions and OH- ions.
Both conditions can speed up various chemical reactions; acids and bases cause most of the chemical transformations that occur in living things. Much of the digestion that occurs in the stomach is due to strong acids (hydrochloric acid) there. ↑

18. Acids and Bases
To create an acidic condition, dissolve an ionic substance in water that releases H+ ions but not OH-.
Similarly, an ionic substance that releases OH- but not H+ is a base. The OH- absorbs the H+ ions already present in the water. An example is lye: sodium hydroxide: NaOH, which dissociates into Na+ and OH-.
Bases are also called alkaline. Ammonia and other compounds that contain NH2 also work as bases.

19. pH Scale
Acidity is measured on the pH scale, which indicates the amount of H+ ions present. The scale runs from 0 (very acidic) to 14 (very basic).
Water, which is neutral, has a pH of 7
Acids have lower pHs: the hydrochloric acid in your stomach has a pH of about 2. Eating food stimulates your stomach to secrete more acid. Antacids (like Tums or Rolaids) neutralize some of this acid.
Bases have a higher pH: the lye in over cleaner has a pH of about 14.
Body fluids are slightly basic, pH 7.4

20. Buffer