How you can explain that #C Cl_4# has no dipole moment?

2 Answers
Sep 19, 2017

Answer:

Well, the molecular dipole moment....

Explanation:

....is the vector sum of the individual bond dipoles. There is some difference in negativity between carbon and chlorine, enuff to give a #""^(+delta)C-Cl^(delta-)# dipole, but when these dipoles are summed together in a vector fashion, the resultant is ZERO......

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On the other hand, chloroform, #"HCCl"_3#, which is more of less identical to carbon tet. geometrically, is a polar molecule, because the vector sum of the individual bond dipoles DOES NOT sum to ZERO.

Mar 5, 2018

Answer:

See below...

Explanation:

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQnY4gltm73HLpTfzPr8GAP3E1Bs4nelViA1OigrUNWp81-oOdSWpYIPcs

Let's have a vector approach.

  • The angle between two #"Cl"# atom is always #color(red)(109^@28'#.
  • So, we have to take the cos component of the three #"Cl"# atoms showing in the pic downside.
  • I mark the upper one as #(1)#, left one as #(2)#, bottom one is #(3)# and the right one is #(4)#.

For #(2),(3),(4)# no. chlorine,the resultant dipole moment is

#mu_((2-3-4))=3xxmu_1 cdot cos(180^@-109^@28')=3xxmu_1xx0.333=3xxmu_1xx1/3=mu_1" "#[#mu_1# is generated dipole moment for each #"Cl"# atom.]

Now, the upper #"Cl"# atom's dipole moment and the resultant dipole moment cancel out each other.

Hence,#color(red)(mu_("CCl"_4))=mu_1-mu_1=0#

This is the answer proved by vector.