CHEM 1&2 Lab Manual & worksheets pg 110

CHEM 1&2 Lab Manual & worksheets pg 110 -...

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Experiment 9: VSEPR General Chemistry I and II Lab Manual Dakota State University Page 110 of 232 Let's see why these molecules are non-polar. The classic example is carbon dioxide, CO 2 , so let's take that one as the example. The Lewis dot structure shows that each oxygen is double bonded to the carbon, the central element, and there are no hydrogens on the carbon. This gives us set number two, and the molecule's parent structure and shape are both linear. We also see that the carbon-oxygen is polar (quite polar) with the oxygen being more electronegative. But, since the molecule is symmetrical, the two dipoles on each side of the molecule are exactly identical, and therefore cancel one another out: One way to think of this is if two children of exactly identical strength were pulling a wagon. If they were pulling in exact opposite directions, the wagon is not moving anywhere; it's stuck. However, if they were not equally strong, or if they were pulling in kind of similar direction,
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Unformatted text preview: then the wagon would move, maybe not towards one of the children exactly, but it would move. As a result, carbon dioxide is non-polar because it is a highly symmetrical molecule. To see why something that is, say, square planar might be non-polar, we have to consider what it would look like. An example of such a shape might be something like [Cu(NH 4 ) 4 ] +2 , which is square planar. Anyway, consider the following diagram: As you can see, if the molecules on diametrically opposed corners are identical, any dipole present would cancel out exactly. This has been kind of vague, but all the information you need is contained within this document. Any questions, comments or suggestions should be sent to me by email, phone, or by stopping by in a friendly little visit WITH NO VIOLINS! EXPERIMENTAL PROCEDURE:...
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This note was uploaded on 01/27/2012 for the course CHM 2045 taught by Professor Josephwalter during the Fall '11 term at Dakota State.

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