For details and practice using the visualization tool, Chime
See the Chime tutorial:
http://c4.cabrillo.cc.ca.us/projects/chime_tutorial/index.htm

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Part 1: Calibrated Peer Review (CPR)
In this part of the assignment that each of you are to do independently, you will:

* Study text and web-based resources on the bonding and molecular structure of water.
* Use your knowledge of covalent bonding and simple molecular construction to write an essay correctly describing the bonding and polarity characteristics of water, H₂O.
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* Go to the CPR Web page: http://cpr.molsci.ucla.edu/
* Click on Tour and follow the guide.
* After completing the Tour, go to login - new user: first time logging in.
* Select DVC and use your DVC id number to login.
* Follow the prompts and be sure to write down the new username that the program will provide you and also the password that you have selected. Don't loose them.

The deadlines for the various milestones and submissions are provided. Be sure that you meet the deadlines since the program will LOCK YOU OUT after the deadline has passed and you will be penalized for not completing the assignment. (Do not worry about HTML tags.)

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Part 2a: Structures and Functions (Can be done with a partner and one sheet turned in for both .)
* Refer to the handout. There are no Web images to refer to.

Part 2b: Click on the following structures IIa- IId, which are linked to files viewable in Chime, and complete the table in the handout provided in class.
 

II a II b II c II d

For hydrocarbons that only have single bonds, it is possible to have a number of different possible arrangements of the respective carbon and hydrogen atoms and their respective bonds. They are different molecules and are referred to as structural or constitutional isomers. They have the same molecular formula but have different physical properties such as boiling points and densities.

For C₄H₁₀, butane, there are two possible isomers, for C₅H₁₀, pentane, there are three. The number of isomers increases steadily with each additional carbon atom but it explodes with more than 10 carbon atoms. C₁₁H₂₄ has 4,347 possibilities and C₁₂H₂₆ 366,319!

Click on the following Web structures.Draw Lewis structures for the two isomers of butane, the three isomers of pentane, isooctane plus two other isomers of isooctane that you are to provided by rearranging bonds and atoms.

Octane, C₈H₁₈, is an important component in gasoline, which is a mixture of hydrocarbons. Gas combustion engines tend to perform best when the gasoline has a large amount of one isomer, "isooctane", present. The larger the amount of isooctane, the higher the octane rating of the gasoline and the more you pay at the gas pump.

Draw a Lewis structure for isooctane and draw two other isomers of octane by rearranging the atoms and bonds. (There are 18 possible isomers in all.)
 

Isomer 1 Isomer 2 butane Isomer 1 Isomer 2 Isomer 3 pentane isooctane

One of the four compounds in Part 2b is an octane booster that is a gasoline additive. The compound is MTBE, and although it is widely used throughout the United States, California has recently banned it. Draw its Lewis structure and briefly explain why it has been banned.

Part 3:

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CO2 and Energy

Sun light is absorbed in plants, which use an enzyme, chlorophyll, as a catalyst to synthesize sugars, carbohydrates and starches. These carbon compounds have the sun's energy converted into chemical bonds which essentially store and provide the energy in various food sources used by man and animals. Without plants, chlorophyll and the sun, life as we know it would be unable to survive.

The images below illustrate photosynthesis of one sugar of the many possibilities, This one is a form of glucose. The multi-colored image in the center frame above the arrow is a structural rendering of a chlorophyll molecule. Only the molecular "backbone" of chlorophyll is shown since this particular protein has over 3600 indivdual atoms.

 

A-1)Write a complete, balanced equation with molecular formulas for the photosynthesis of glucose, the above sugar.
 

A-2)  The sugar that is produced contains two of the four chemical functions in Part 2a. Identify them.

A-3)  How many grams of pure CO_{2 (g)} would be needed to produce 100. g of glucose (about a quarter of a pound)? Show your calculation.

Combustion of Hydrocarbons / Atmospheric CO_{2 (g)}

Plant and animal carbonaceous materials have been converted to "crude oil" through microbial action and geochemical forces working over millions of years. The hydrocarbon "crude oil" that is pumped from underground and undersea deposits is processed into fuels ("fossil fuels") which are burned to release chemical energy for manufacturing, transportation and conversion into electricity.

The reaction below is the combustion (burning) of isooctane, an important component of gasoline.

B-1) Write a complete, balanced equation with molecular formulas for the combustion of isooctane.
 

Extra Credit:
B-2)  How many grams of CO_{2 (g)} are produced from the combustion of 1 gallon of isooctane? (Isooctane density = 0.69194 g/mL, 3.785 L = 1 gallon). Show your calculation.

© Copyright 2003 R.J. Rusay