1. Solutions 1 1 1 1

2. What Is A Solution? Everything! (har har) What's the matter?
Pure Substances have a definite set of physical properties.(melting point, density, reactivity, etc)
Elements
Compounds
Mixtures are two or more substances physically combined but not chemically combined
Heterogeneous- a mixture that is not uniform throughout.
Examples: dirt, chocolate chip cookies, you
Homogeneous- uniform throughout
Solution- a special homogeneous mixture where one substance is dissolved into another. Almost always clear.
Examples: Salt water, syrup, rubbing alcohol 2 2 2 2

3. Mixtures
Activity:
1. Left-hand side of your notebook, draw 4 gas tanks and label them “H2 Gas,” “O2 Gas,” “Hydrogen & Oxgen compound,” and “H2 & O2 Mixture.”
2. Fill each tank with the appropriate molecules. Use open circles for hydrogen atoms and filled-in circles for oxygen atoms.
H2 Gas
O2 Gas
Oyxgen & Hydrogen
Compound
O2 & H2
Mixture
Pure
Pure
Pure
Not pure
Not pure 3 3 3 3

4. Solutions Solutions have two components:
Solvent – major component of a solution, dissolves the solute
Solute – minor component of a solution,dissolved by solvent
The solute is the active ingredient of a solution.
Steps of solution process:
1. Solute particles separate - absorbs energy to overcome intermolecular forces holding particles together
2. Solvent molecules separate - absorbs energy.
3. Solvent particles surround solute particles – releases energy
Known as “solvation”.
Solutions that release more energy than absorbed are called exothermic (energy EXiting).
Solutions that absorb more energy than released are called endothermic (energy ENters) 4 4 4

5. Solutions Separating Mixtures:
distillation – using different boiling points to separate substances in a mixture
Examples: desalination
filtration – Using particle size to separate substances through a semi-permeable membrane.
Examples: air filter in a car, tea bag, coffee filter
Chromatography- using a molecule’s ability to move through a medium.
Examples: gel electrophoresis, HPLC 5 5 5

6. Solubility Solubility- able to be dissolved
Solids, liquids and gases can be dissolved.
Remember “like dissolves like”
Ionic & polar solutes dissolve in polar solvents.
Non-polar solutes dissolve more in non-polar solvents.
Immiscible - liquids that are not soluble in each other
Ex: Oil and water do not dissolve in each other because of different polarities 6 6 6 6

7. Solubility Rules Page 6 of the NC Chemistry Reference Tables
Use the rules to determine solubility of certain ionic substances 7 7 7

8. Temperature & Pressure
Temperature and Pressure affect solubility
Solids dissolve better at higher temperatures, pressure has no effect
Example: tea that is heated can dissolve more sugar
Gases dissolve better at lower temperatures and high pressure
Example: soda bottles are kept cold and under pressure (closed) 8 8 8

9. Saturation
Saturated solution- solution containing the maximum amount of solute for a specific amount of solvent at a given temperature and pressure.
More solute will not dissolve
Unsaturated solution- does not contain the maximum amount of solute in solution.
More solute can dissolve until the maximum is reached
Supersaturated solution- an unstable solution that contains more solute than it can theoretically hold at a given temperature
Created by cooling a saturated solution
Adding more solute causes the excess solute to precipitate
Precipitate- a solid that forms and settles down in a liquid mixture 9 9 9

10. Solubility Curves
Solubility Curve– graph of solubility versus temperature
compares the solubilities of multiple compounds in water as a function of temperature.
solubility is expressed in terms of grams of solute per 100 grams of H2O. 10 10 10

11. Solubility Curves
How many grams of KNO3 can dissolve in 100 grams of water at 30ºC?
Answer: About 48 grams. 11 11 11

12. Solubility Curves
How many grams of KClO3 can dissolve in 100 grams of water at 55ºC?
Answer: About 25 grams. 12 12 12

13. Solubility Curves
How many grams of NH4Cl can be dissolved in 200 grams of water at 40ºC?
Answer: About 96 grams. 13 13 13

14. Solubility Curves
A saturated solution of NaNO3 is prepared at 70ºC in 100 grams of water. If the temperature is lowered to 40ºC, how many grams of NaNO3 will precipitate?
Answer: About 30 grams will precipitate out. 14 14 14

15. Solubility Curves
If 35 grams of NH4Cl are dissolved in 100 grams of water at 30ºC, is the solution unsaturated, saturated, or supersaturated?
Answer: The solution is unsaturated. 15 15 15

16. Solubilities of Gases
Henry’s Law – The solubility of a gas in a liquid increases as the pressure above the liquid increases.
Explains decompression sickness (the “bends”).
Nitrogen is forced to dissolve in scuba divers’ blood by high pressure.
If the diver ascends too quickly, the nitrogen bubbles come out of solution and form painful and possibly fatal gas embolisms. 16 16 16