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Topic: Dipole Moment!!!!!!!!!  (Read 5026 times)

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Offline stacker

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Dipole Moment!!!!!!!!!
« on: December 15, 2009, 07:20:09 PM »
Ok I'm very tired because I've spent the past 50 minutes trying to figure out a problem that should take only 5. Someone please just take 2 minutes of your time to save me 20 more minutes. THis is a simple problem yet I cannot do it on my own, without my textbook and with what vague description there is on the internet.

"The bond length of LiBr is 255 pm. What would be the dipole moment, in D, of this compound assuming an ionic bond?"

I've tried using this equation of multiplying the charge of an electron by the bond length (in picometers) converted to meters. I got the wrong answer: 4.086 x 10 ^ -29.

That is, I multiplied "1.60217646 × 10-19 coulombs" by "255 x 10 ^ -29"

Offline Schrödinger

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Re: Dipole Moment!!!!!!!!!
« Reply #1 on: December 15, 2009, 10:09:13 PM »


"The bond length of LiBr is 255 pm. What would be the dipole moment, in D, of this compound assuming an ionic bond?"

I've tried using this equation of multiplying the charge of an electron by the bond length (in picometers) converted to meters. I got the wrong answer: 4.086 x 10 ^ -29.

That is, I multiplied "1.60217646 × 10-19 coulombs" by "255 x 10 ^ -29"

That exponent of yours is wrong (pm to m conversion) (probably that was a typo :P).

Your final answer :  4.086 x 10 ^ -29 is right, but in what units?
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Offline savy2020

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Re: Dipole Moment!!!!!!!!!
« Reply #2 on: December 16, 2009, 02:19:42 AM »
I've tried using this equation of multiplying the charge of an electron by the bond length (in picometers) converted to meters. I got the wrong answer: 4.086 x 10 ^ -29.

That is, I multiplied "1.60217646 × 10-19 coulombs" by "255 x 10 ^ -12"
It is correct but it is 4.086*10-29 C m .
But generally Dipole moment is calculated in Debye(D).
Refer this http://en.wikipedia.org/wiki/Bond_dipole_moment

Please always take care of units. Write them in each step. :)
:-) SKS

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