AP Chemistry Thou Shalt Not Forget Factoids UNIT 3

from: https://docs.google.com/document/d/1AScbyP4FkHe7uLIVa-0-MEX4gtVY1rSUQuIEcYndqG0

Unit 3A Properties of Liquids and Solids--IMF’s

1. IMF’s from weakest to strongest:

   1. London Dispersion

   2. dipole-dipole

   3. hydrogen bonding

   4. ion-dipole.

2. All molecules contain LD forces, and this force gets stronger as the molecule is larger.

   1. Larger electron cloud = more LD = more polarizable.

3. All polar molecules contain dipole-dipole forces, and this force gets stronger as the molecule is more polar.

4. H-bonds are between a NOF in one compound to a hydrogen that’s already bonded to a NOF in another compound.

5. Boiling point and melting point increase as IMF’s increase.

6. Vapor pressure and volatility decrease as IMF’s increase.

7. Molecular solids have low melting/boiling points, and they do not conduct electricity.

8. Ionic solids have high melting/boiling points, and don’t conduct electricity as a solid, but DO conduct as a liquid or (aq).

9. SiO₂ (quartz) and diamonds are covalent network solids, and they have very high boiling/melting points.

10. Metallic bonds are between metals, and they ALWAYS conduct electricity, and their hardness varies.

11. When a molecular solid melts or boils, it is the IMF’s between the molecules that break, not the covalent bonds.

12. Alloys:

    1. Interstitial alloys are made when a smaller atom fits into the gaps between the larger atoms of a metallic crystal.

    2. Substitutional alloys are made when the radii of the metals are similar in size and are substituted into the crystal lattice. 

Unit 3B Gases, Solutions, and Chromatography

1. Gas mixtures are homogeneous because of the constant random motion of the particles.

2. Gases are compressible because of the large spaces between the particles.

3. Gas pressure is caused by collisions of particles with the walls of the container.

   1. More Collisions = More Pressure

4. P and V are inversely related

   1. doubling the volume of a container will cut the pressure of the gas in half.

5. T and V are directly related

   1. If you heat a balloon, it will expand.

6. T and P are directly related

   1. If you heat a rigid container, the pressure of the gas will increase.

7. PV=nRT is the ideal gas law.

   1. Units:

      1. Temperature = Kelvin;

      2. Volume = Liters;

      3. Pressure = atm

   2. Use this gas constant→ R=0.08206 

8. Gas pressure and # of moles are directly related

   1. if you double the mole of gas in a container, the pressure will double. 

9. Molar Mass = dRT/P

   1. The “d” stands for density in units of g/L

   2. Use this gas constant→ R=0.08206  

10. The more molar mass a gas has, the slower it moves at a given temperature.

11. Temperature = Average Kinetic Energy

    1. (Gases at the same temperature have the same average kinetic energy.)

12. When collecting a gas by water displacement: P_total = P_{dry gas} + P_{water vapor}

13. Real gases behave most like an ideal gas at high temperature and at low pressure.

    1. The more polar a gas is and the larger a gas is, the more it will deviate from ideal behavior.  Consequently, small, nonpolar gases are the most ideal.

14. Filtering separates mixtures based on differences in particle size: the large particles are trapped on the filter paper while the soluble component goes through the filter paper and stays in the “filtrate”.

15. Distillation separates mixtures based on differences in boiling point.

16. Chromatography separates mixtures based on differences in polarity.

17. In paper chromatography, the component that is most similar in polarity to the “mobile phase” moves up the farthest.