Unit 11: Solids and Liquids
Reading
BJU Chemistry: Ch. 11 "Solids and Liquids"
AP Classroom Unit 6 'Thermochemistry' (continued)
Topics
Labs (we'll take a vote)
BJU Chemistry: Ch. 11 "Solids and Liquids"
AP Classroom Unit 6 'Thermochemistry' (continued)
Topics
- Intermolecular forces: Hydrogen bonds, dipole-dipole forces, dispersion (London) forces.
- Properties of solids and liquids
- Separation processes: distillation, crystallization
- Measuring melting points, freezing points
Labs (we'll take a vote)
- Boron Compounds/Flame Test lab
- Distillation lab (Fractional distillation of ethanol-water mixture)
| chemical_bonding_CHART.pdf |
| 11._solids_&_liquids_exercises_11.1-11.34.docx |
Solids and liquids are held together by INTERmolecular forces (IMF's). The atoms in a solid vibrate in place, while the atoms in a liquid can slide past one another.
|
LIQUID STATE
|
Overview
Up to this point we have been discussing INTRAmolecular forces, the forces which BOND ATOMS together into COMPOUNDS. These fall into three broad categories: 1) Ionic bonds, 2) Covalent bonds, and 3) Polar-covalent bonds. We also discussed Metallic bonds, as well.
Now we are switching gears and talking about INTERmolecular forces, the forces which make molecules stick to one another to form LIQUIDS and SOLIDS.
These INTERmolecular forces (IMF's) come in three types:
All three of these intermolecular forces are termed "Van der Waal" forces. This can sometimes be a source of confusion.
Intermolecular forces are WEAK forces: A hydrogen bond represents only about 20 KJ/mol, and Dispersion forces only represent <5 KJ/mol in strength - whereas a typical Covalent bond is around 400-500 KJ/mol. However, if intermolecular forces were much stronger we wouldn't have any liquids or gases in nature; everything would just be a SOLID, and life wouldn't exist! Many have pointed out the evidence of fine-tuning and intelligent design.
Up to this point we have been discussing INTRAmolecular forces, the forces which BOND ATOMS together into COMPOUNDS. These fall into three broad categories: 1) Ionic bonds, 2) Covalent bonds, and 3) Polar-covalent bonds. We also discussed Metallic bonds, as well.
Now we are switching gears and talking about INTERmolecular forces, the forces which make molecules stick to one another to form LIQUIDS and SOLIDS.
These INTERmolecular forces (IMF's) come in three types:
- Dipole-dipole forces, the electrostatic attraction between the (+) and (-) ends of polar molecules
- Hydrogen bonds, the electrostatic attraction between a Hydrogen on one molecule, and either Oxygen, Nitrogen, or Fluorine on an adjacent molecule
- Dispersion forces (London forces), the weak electrostatic attraction between non-polar molecules which arises from an unequal distribution of their respective electron-clouds at any given instant.
All three of these intermolecular forces are termed "Van der Waal" forces. This can sometimes be a source of confusion.
Intermolecular forces are WEAK forces: A hydrogen bond represents only about 20 KJ/mol, and Dispersion forces only represent <5 KJ/mol in strength - whereas a typical Covalent bond is around 400-500 KJ/mol. However, if intermolecular forces were much stronger we wouldn't have any liquids or gases in nature; everything would just be a SOLID, and life wouldn't exist! Many have pointed out the evidence of fine-tuning and intelligent design.
Distillation of Ethanol-Water Mixture lab
We will make ethanol and use fractional distillation to concentrate it. This is a classic, fun chemistry lab. Bring the handout with you to the lab. I will have instructions.
We will make ethanol and use fractional distillation to concentrate it. This is a classic, fun chemistry lab. Bring the handout with you to the lab. I will have instructions.
| 0._distillation_of_ethanol-water_mixture_lab.pdf |
|
|
Boron Compounds lab
- Prepare some compounds with interesting properties based on the element 'Boron'
- Flame tests to observe emission spectra of various metals.
| boron_compounds_lab_handout.pdf |
| flame_test_chart_metal_ions.png |
| 11._solids_and_liquids_exercises_student_examples.pdf |