Final Exam - Exam 2 Recap Flashcards
Define intermolecular forces?
Forces of attraction that occurs between atoms, molecules, and ions due to their proximity to each other. These are weaker than intramolecular forces (covalent, ionic).
Why may intermolecular forces appear stronger than intramolecular forces?
Because of the large number of interactions.
What affects the strength of attraction between intermolecular forces?
- Magnitude of charge (real or partial)
- Distance between atoms
The stronger the attractive forces, the more they resist breaking apart.
How does solubility relate to intermolecular forces?
Solubility depends on attractive forces of the solute and solvent. “Like dissolves like”.
Describe the weakest intermolecular force?
Van der waals (London dispersion) forces: arise from formation of induced dipoles between two nonpolar molecules
List the intermolecular forces from weakest to strongest?
Van der waals, dipole-dipole, hydrogen bonding, ion-dipole, ion-ion
Describe dipole-dipole interactions?
Occurs in all polar molecules. Strength depends on the nature of individual dipoles.
Describe hydrogen bonding?
Very strong specialized dipole-dipole interaction. Strongest when N, O, and F involved.
What are electrostatic interactions?
Ionic interactions between a cationic and anionic portion. Effective at distances further away and persist longer.
What does solubility of one substance in another depend on?
Intermolecular forces (like dissolves like)
* More polar bonds means more water soluble
Which substance is water soluble and which is fat soluble?
Vitamin C is very water soluble to due to multiple polar groups (-OH, C=O)
Vitamin E is fat soluble because there is only two polar group and many C-H bonds
What is a saturated solution?
When the solvent holds the maxiumum amount of dissolved solute
No more solute can be dissolved if added
What is an unsaturated solution?
When the solvent holds less than the maximum amount of solute dissolved
Addition of more solute will dissolve in solution
What is a supersaturated solution?
When the solvent holds more than the maximum amount of solute (unstable)
Ex: adding more solute by heating, then after cooling addition of more solute will cause crystalization
How do you calculate weight percent?
mass solute / mass solution x 100
Solution will be given as (w/w).
Assume the percentage is out of 100 g sample.
How do you calculate volume percent?
volume solute / volume solution x 100
Solution will be given as (v/v).
Assume a 100 mL sample.
