Question 5d (UPDATED)

Does CO have an entry for global warming potential in the IPCC reports?  The book said it doesn’t.

Question (?)

How do yo tell the difference in the levels of Carbon Dioxie, Methane, and Nitrous Oxide in the northern and southern hemispheres?

The determining factor for a gas to be a greenhouse gas is if it absorbs IR radiation. To find out which ones are infrared active, the first step is to use the VSEPR theory to see if the bonds are polar through its molecular shape. Then, see if the overall molecule is polar. After that, check each molecular vibration too see if there is a dipole moment and whether it has brought about a net change.

Making the Link

You can tell that a gas is a greenhouse gas because it absorbs IR radiation.  Polar bonds and different polarity cause molecules to absorb IR radiation.  Therefore, greenhouse gases have polar bonds and absorb IR radiation.

Making the Link

A gas is a greenhouse gas if it has an asymmetric stretch. The bond dipoles in molecules with asymmetric stretches absorb infrared radiation

Making the Link

To determine if a gas is a greenhouse gas, we must first determine the shape of the molecule. Next we determine if the molecule is polar or nonpolar. Then, the vibrations that occur as a result of the bond dipole moment shifting indicate that IR absorption takes place. Important things to note: Polarity does not determine whether a gas is a greenhouse gas, it is the net bond dipole moments changing that indicate a gas is a greenhouse gas. For instance, Methane is nonpolar overall, but it is still a greenhouse gas. Also, when a gas molecule stretches, the kind of stretch is important for figuring out if it absorbs IR. An asymmetric stretch absorbs IR because the bond dipoles are moving more to one side than to the other.

A little confused…

I’d really like it if we could go over the table in Session 4 as a class. I was kinda confused by the rates and percentages.

Making the Link

To determine if a gas is a greenhouse gas, we muct determine if it absorbs infrared radiation. To do this, we determine the polarity of the molecule, and the dipole moments of the bonds that make up the molecule (basically determining how the bond moves). By determining if the molecule absorbs infrared radiation we thereby determine greenhous gases.

Making the Link

Using Lewis structures and the VSEPR theory to predict the shapes of molecules, we can figure out the polarity of the bond and the molecule. Then we can find the stretch of a molecule. If this stretch is asymmetric or bent, the dipole moment changes and the molecule can absorb infrared radiation. If a molecule absorbs infrared radiation, then it is a greenhouse gas.

Class Assignment

Ok everybody, as requested by Dr. Metzker, the assignments for this week are as follows:

1. Don’t go to class.

2. Don’t go to lab.

3. Acquire a copy of the CD from the Global Warming workbook, and do something with it…

4. Post a paragraph to the blog from Section 3 question 8 or Making The Link (whichever is easier).

5. Work through Workbook Section 4 alone with a partner.

6. Work on your group semester project if you so desire.

7. ????????

8. Show up for class sometime Tuesday.