1. (Chemists have Solutions!)
Unit 4: Solutions
(Chemists have Solutions!)

2. Definitions
Solution: Homogenous mixture of two or more substances in a single phase
Solvent: is the component of a solution that exists in the greatest quantity.
Solute: is the component of a solution that exists in the smaller quantity.
Saturated Solution: A solvent is said to be saturated with a solute, when no more solute will dissolve into it.
Unsaturated Solution: is one in which more solute can be dissolved

3. Definitions
Soluble: a solute is soluble in a solvent if the solute and the solvent mix to form a homogenous mixture.
Insoluble: a solute is said to be insoluble in a solvent if less than 0.1 moles of the solute will dissolve in a liter of solution
Solubility: is the maximum amount of a given solute that dissolves in a given solvent at a given temperature. I.e., when measuring the solubility of a system it must be for a saturated solution.

4. Units of Solubility
Solubility is the maximum concentration of a solute in a solvent for a given temperature. Units of solubility are:
Grams(solute)/liter of solution
Moles(solute)/liter of solution (M, molarity)

5. Determining Solubility
Must prepare a saturated solution
Use an xs amount of solute (goal is to have some un-dissolved solute separate from the solution)
Mix thoroughly and let sit over night at a constant temperature
Pipette a known amount of the saturated solution (25.00 ml) into a pre-weighed weigh boat
Evaporate solution to dryness (remove solvent)
Determine the weight of the solute
Calculate solubility in grams/liter (convert to mol/L if required

6. Properties of Solutions
Conductivity: is a measure of how well a solution conducts electricity. ( for a solution to conduct electricity, it must contained charged particles, I.e., IONS)
pH: the pH of a solution is a measure of how much H+ ions are in solution, the lower the pH the more H+ ions there are present , the Higher the pH the less H+ ions there are. Neutral water has a pH of 7.0 ( at 25 C.)

7. Dissolving Vs. Dissociating
Dissociating is when an Ionic compound breaks down into its ions in solution
Dissolving is when a covalent compound is absorbed by the solution, however it keeps its same chemical composition.

8. The Theory of Solubility
Polar solvents will dissociate ionic compounds and dissolve polar covalent compounds
Non-polar solvents will dissolve only non-polar covalent compounds.

9. What is Polarity?
A compound is said to be polar if it processes a net permanent dipole moment that do not cancel each other out.
Permanent dipole moments occur in covalent molecules where bonds exists between atoms with different electron-negativity.
A Net permanent dipole occurs when all the dipoles in a molecule do not cancel each other out.

10. Molecular Shapes and Polarity

11. Importance of Polarity
Polarity effects the solubility of a solute in a given solution
Polarity effects the phase a pure compound will likely be in
Polarity effects the shape of large molecules such as proteins

12. Intermolecular Forces Vs. Intramolecular Forces
Intramolecular forces: are the forces internal to the molecule. They are responsible for holding the atoms in the molecule together.
Intermolecular Forces: are the forces between molecules
Dipole/Dipole interactions (polarity)
Hydrogen bonding
London forces