1. Solutions

2. Solution – homogeneous mixture in which solute & solvent particles are evenly distributed in one another
solvent – the dissolving medium; thing that does the dissolving
solute –the dissolved particles; thing that is dissolved
solutes and solvents can be solids, liquids, or gases

3. Solubility – amount of solute that dissolves in a quantity of solvent at certain temperature and pressure
Solutions can be:
a) unsaturated – contains less solute than solvent can possibly dissolve
b) saturated – contains as much solute as can be dissolved by solvent

4. c) supersaturated – contains more solute than can normally be dissolved by solvent; not very stable – slight disturbance to solution will cause solute to precipitate or crystallize

5. Terms related to solubility
soluble – substance that will dissolve in a solvent
insoluble – substance that will not dissolve in a solvent
miscible – when 2 liquids will dissolve in each other in any proportion (ex: water and ethanol)
immiscible – when 2 liquids are insoluble (ex: water and oil)

6. Electrolytes
excellent conductors in liquid state or dissolved in water (aqueous)
In order for a solution to carry an electrical current, it must contain ions that are free to move.
Acids, bases and ionic compounds all ionize (break into ions) in water to form free ions.

7. Factors Affecting Solubility
agitation of the system – increases collisions between solute and solvent particles
particle size – smaller dissolves faster because more surface area
temperature – solutes generally dissolve faster at higher temps.
– higher kinetic energy at higher temps.
– stronger and more frequent collisions between solute and solvent particles
- Exception: solubility of gases inversely proportional to temperature

8. Concentration of Solutions
Molarity – M – mols of solute per L of solution
Example: 5 M – dissolve 5 mol of solute in enough solvent to make 1 L of solution

9. Calculating molarity (M)
convert mass of solute (g) to mol using molar mass
convert volume of solution to L
use formula:
M = mols solute
literssolution

10. Example 1
What is the molarity of 2.3 moles of sodium chloride in 0.45 liters of solution?
M = mols solute
literssolution
M = 2.3 mol = 5.1 M
0.45 L

11. Example 2
What is molarity of a solution prepared by dissolving g of KOH in H2O, then diluting the volume to 500 mL?
mass = g KOH mol KOH = 0.676mol g KOH
molar mass KOH
volume = 500 mL 1 L = L
1000 mL
molarity = mol = 1.35 M
0.500 L

12. Dilutions
stock solution – mixture w/ high concentration of solute; can be diluted by adding additional solvent to get molarity needed
use this equation to solve for unknown:
M1 · V1 = M2 · V2

13. Example
What is the molarity of a solution that is made by diluting 50.0 mL of 4.74 M solution of HCl to mL?
M1 = 4.74 M
V1 = 50.0 mL
M2 = ?
V2 = mL
M1V1 = M2V2
M2 = M

14. “Like dissolves like” Rule
Polar solvents dissolve ionic and polar solutes
partial positive & negative charges of polar molecules are attractive to one another
Due to an uneven sharing of electrons in a molecule
polar solvents with partial + and – charges are attracted to + and – ions in ionic compounds
Nonpolar solvents dissolve nonpolar solutes

15. The Uniqueness of Water!
Structure of H2O
Lewis Dot Structure
VSEPR Shape
Electronegativity (H=2.1 and O=3.5)
Hydrogen bonding

16. Physical Properties of Water
Density of Ice
Universal Solvent
High melting and boiling points
Cohesion (surface tension)
Adhesion (capillary action)
High specific heat (ability to hold heat)
ALL OF THESE ARE DUE TO THE STUCTURE OF WATER (polar and hydrogen bonds)!!!