Polar vs Nonpolar Example

(Polar molecules, Non-polar molecules, etc.)

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Polar vs Nonpolar Example

Postby ngarcia » Fri Nov 15, 2019 9:04 pm

In today's lecture, Professor Lavelle used cis-dichloroethene as an example of a polar molecule and trans-dichloroethene as an example of a nonpolar molecule. This made me very confused because they have the same structure (according to the powerpoint), but the arrows were in different areas. Can someone explain how that works?

Rohan Kubba Dis 4B
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Joined: Sat Aug 17, 2019 12:18 am

Re:olar vs Nonpolar Example

Postby Rohan Kubba Dis 4B » Fri Nov 15, 2019 9:22 pm

Basically, a good example to look up is 2E30. (Yes I know it is an even question, but it is a good example). If you look at it there are three forms of essentially the same element. In the second and third versions, these are the trans and cis versions of the molecules respectively. Essentially in the trans version shows fluorine on the opposite side and on the other end:

C––C (Carbon is double bonded)

And the cis version shows this:


Essentially when you look at the structure, there is no dipole moment isn’t he trans versions because vectorally, the values cancel out, making it non polar, however in the cis version, the vectors are not cancelled out, making it polar (because it has a dipole moment).

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Re: Polar vs Nonpolar Example

Postby Megan_1F » Fri Nov 15, 2019 9:33 pm

The trans version will have the dipoles canceling each other out (opposite ends), thus there is no dipole moment and the molecule is Nonpolar. In the cis version, the dipoles do not cancel each other out, thus creating a dipole moment making the molecule polar.

Alexa Mugol 3I
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Joined: Sat Aug 17, 2019 12:17 am

Re: Polar vs Nonpolar Example

Postby Alexa Mugol 3I » Fri Nov 15, 2019 10:39 pm

In cis-dischloroethene, the Cl atoms are on the same side, so the partial negatives are on the same side. Therefore, there's a big area with partial negative and the other side is partial positive. In trans-dischloroethene, the Cl atoms are on opposite sides of each other, so the partial negatives cancel out since the partial charges are balanced.

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