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Quiz for Chemistry in a New Light
Copy each question below into an email and answer the questions there. (No need to copy the images). Mail your answers to your instructor at chm151@chemistryland.com

1. You learned that chemistry involves 3 areas of focus: Building blocks, Force/Energy, and math. Let's say you are teaching your little girl how to make a cake. You will explain it to her using these 3 areas of focus.

1a: What building blocks will you mention that make a cake?

1b: What force or energy aspects will you mention?

1c: What math is involved in making a cake?

 

sugar alcohol molecules

2. Building blocks:
Here is a progression of molecules that starts with one carbon going up to six carbons.
(Note: a molecule means a group of two or more atoms). The smallest molecule is methanol (a racing fuel) which has four hydrogen atoms (H), one carbon (C), and one oxygen (O). The next is ethylene glycol (car antifreeze). The next four are often used as artificial sweeteners. There's a group of 4 atoms that is the basic building block for all of these molecules.
What is that group of 4 atoms?

methanol, glycerol, and mannitol

3. Force and Energy: Here are three compounds from #2. Let's focus on the force and energy aspects. You've heard of the states of gas, liquid, and solid. The reason for these states is the force of attraction between the atoms or molecules. The stronger the attraction, the more likely it becomes a solid. Methanol becomes a vapor (a gas) very readily. Ethylene glycol stays a liquid even when hot. Mannitol is a solid.
3a. All of these can be turned into a vapor (gas). Which one do you think would take the most energy (most heat) to turn into a vapor?

3b. Which of these has the longest chain of carbons?

MELTING POINTS
Methanol:
-96 degrees Celsius
Ethylene glycol: -12.9 degrees Celsius
Glycerol (glycerin): 18 degrees Celsius
Erythritol: 121 degrees Celsius
Arabitol: 103 degrees Celsius
Mannitol: 166 degrees Celsius

fire animationfire animation

4. Math:  Here are the compounds from #2. Now we are using math to better understand these compounds.
The melting point of a compound reflects how strong the molecules are held together. The stronger they are held together the more heat is required to shake them enough so they will break loose from each other (that's the melting point).
4a. Which one of these compounds in the list has the weakest force holding them together?
4b. Which one has the strongest force holding the molecules together?
4c. The pattern seems to be... the longer the carbon chain, the higher the melting point. There is one exception here. Which one?

5. Building block: This molecule is called iron porphyrin. It's very similar to the molecule in hemoglobin. The "heme" in hemoglobin is referring to a molecule almost like this one. The green spheres here are carbon atoms. The blue ones are nitrogen atoms, and the small white ones are hydrogen atoms. In the center is iron (pink atom). The major building block for this molecule is a five atom ring (4 carbons[green] and 1 nitrogen[blue]) bridged using one carbon atom with a hydrogen atom. Roll cursor over image to see this group.

5a. How many groups make up this molecule?

5b. Draw this molecule on paper (don't worry about colors). First copy what you see here, then try to draw it without looking. What tips would you give others about drawing this molecule from memory?

thermite reaction

THERMITE: Some crazy neighbor shows you this reaction in his back yard. He calls it a "thermite" reaction. You want to do the same thing.

6. Keeping in mind "Chemistry in a New Light" and its 3 areas of focus, what questions might you ask so that you can repeat this demonstration and understand what is going on?

Note: This picture is from www.amazingrust.com. Below is a link to a video of the thermite reaction from the website. It's in wmv format (a Windows video format):
http://www.amazingrust.com/...Thermite(Fe2O3).wmv

 

For students in Phoenix College's CHM151 class, send your answers to me (Ken Costello) at chm151@chemistryland.com

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