CHEM 1411 - General Chemistry I
Course (Lecture and Lab) Syllabus
Summer 2007
Instructor: Dr. Shawn Amorde
e-mail address: samorde@austincc.edu
web page: http://www.austincc.edu/samorde
Office Hours: TThF, 7-8am
Liquids and Solids
Text Chapters (13.1-13.8, 13.12, 13.15, 13.16)
Recommended Problems (1,2,4,5,6,7,8,,9,10,12,14,16,22,26,28,76, 78, 80,82)
Liquids
1. Description and properties
2. Intermolecular Forces
3. Viscosity
4. Surface Tension
5. Capillary Action
6. Evaporation
7. Vapor Pressure
8. Boiling Points
9. Heat Transfer
Solids
10. Melting Point
11. Heat Transfer
12. Sublimation and Vapor Pressure
13. Structures
of
14. Bonding
Liquids
We have just discussed the properties of gases and how we can relate a series of laws and equations to their properties. Gas molecules are so diffuse that they do not interact with each significantly, this is not true of liquids and solids. We will look at a large number of properties of both liquids and solids, but due to the large number of these interactions and variety of interactions there are no general equations to summarize their behavior.
Let’s review some of the properties of liquids.
- Shapeless on their own, take the shape of a container
- Have a definite volume
- Only slight compressible
- Have a high density
- Are fluid
- Diffuse through other liquids
- Disordered clusters of particle close to each other
- 3-D motion which is random
Remember liquids are particles which close enough together to interact heavily and based on those interactions we know that some liquids will mix and some won’t. Remember polarity? Non-polar and polar compounds do not mix well, due to the difference in their properties and in liquids they are forces next to each other. Like dissolves like.
Liquids which can diffuse together are said to be miscible. Miscible liquids will mix together and immiscible liquids do not. This property of liquids is absolutely integral to our lives!!
Let’s look at oil and water for an example.
All of the properties of liquids depend on intermolecular forces!! The strength of these intermolecular forces help determine their boiling points, vapor pressure, viscosity, and so on.
These are relatively weak compared to intramolecular forces, i.e. covalent and ionic bonding.
Let’s look at these forces;
Ion-Ion Interactions
Remember E is proportional to charge and distance!!
Dipole Dipole
Interactions
Hydrogen Bonding
Dispersion Forces
The
We have just learned that liquids flow, but what does that mean? We know that some liquids flow fast, like water and some slow like molasses. This difference is viscosity. Viscosity is the resistance to flow.
The stronger the intermolecular forces the greater the viscosity.
Surface Tension
The attraction of molecules on the surface toward the interior of the solution is called surface tension. This tension is the least where the area interfacing the surface is the least, thus a sphere.
Capillary Action
The forces holding a liquid together are called cohesive forces, the attractive forces between a liquid and the surface are called adhesive forces. This can cause a liquid to adhere to its container, like water to a glass.
We have seen this with our buret lab and the meniscus. This attraction can be seen when a liquid “climbs up” the sides of a tube, this is called capillary action.
Evaporation
Those molecules at the surface of a liquid which possess enough kinetic energy to break away and enter the gas phase. Kinetic energy is temperature dependant!!
The reverse is also true and this called condensation.
Vapor Pressure
Vapor molecules cannot escape when trapped in a closed container, this builds pressure called the vapor pressure. This is temperature dependant.
When we heat a liquid and raise the kinetic energy of the liquid raising the vapor pressure. When this temperature reaches a point (under constant pressure) in which bubbles of vapor form below the surface…..this is the boiling point.
If you have a mixture of liquids, you can rely on this property to “boil off” the lowest boiling point liquids first and essentially separate the liquids. This process is called distillation.
The
The melting point of a solid is the temperature in which the solid and liquid forms co-exist. Directly going from solid to gas is called sublimation.
All three states can occur at a specific temperature and pressure, this is called the triple point.
Structures of
All crystals contain regularly repeating units of atoms, molecules, or ions. The smallest unit of volume of a crystal which contains the crystal’s pattern is called the unit cell. There are several sizes and shapes of unit cells, some are diagramed in your book, pg 476 for observation.
This is the difference between graphite and diamond!!
Bonding
There are four main characteristic bonding types seen in solids. Metallic, ionic, covalent, and molecular. The characteristics are summed up in the text on page 477.
These characteristics are the same for what we have discussed, what is different is what makes up the unit cell and what holds it together!!
Lets sum it up.