Question

Which has highest dipole moment??

CH3Cl, CH2Cl2, CHCl3 or CCl4.

well, I saw a video or Merit nation and i found that the answer that I had to this question is wrong.

I thoungh that CH2Cl2 had highest Dipole Moment but the answer was given as CHCl3 in merit nation.

SO, i'll tell my logic to the answer, Pls tell me how I am wrong.



OK, Now CHCl3 has one C-Cl bond. We will keep it's dipole moment as A.

CH2Cl2 has two dipole moments each of A value. If each has A value, we can vectorially add them and get the dipole of the combination as 2(cos(109.5/2))A. that comes to be 1.14A.

CHCl3 will have a dipole moment of A in the opposite direction of the hydrogen by the same logic as above.

CCl4 will have 0 Dipole moment with the same logic as above.

Can you please tell me where I went wrong??

Answer 1

O yes, you 're wrong . CHCl3 has highest dipole moment.

Let see, how it's possible ?

dipole moment is what just a combination of two opposite nature charge placed in very small distance right ?

you also know, electronegativity of C and H comparatively same.

so, we can assume C-H bond doesn't form dipole [ it is considered only for understanding.]

Cl is 2nd most highest electronegativity element.

so, C - Cl bond must form a reasonable dipole moment.

now see figure , here you see CH3Cl has only one C - Cl bond.

if we assume dipole moment of C-Cl bond is P

Then, dipole moment of CH3Cl = P

Now, CH2Cl2 has two C-Cl bond and it has inclined some angle $\theta$

then, dipole moment of CH2Cl2 = √(P² + P² + 2P² cos$\theta$

) ≥ P

in case of CHCl3 , it has three C-Cl bond so, dipole moment of CHCl3 = P + √(P² + P² + 2P²cos$\theta$) ≥ √(P² + P² + 2P² cos$\theta$) ≥ P

you already said , dipole moment of CCl4 = 0, because it has symmetrical shape.

now, can you say which has highest dipole moment , of course CHCl3.

Answer 2

Answer:

• CH2Cl2 has the highest dipole moment.

Explanation:

• H3Cl>CH2Cl2>CHCl3>CCl4
• 1-This is due to in CH3Cl chlorine is EWG and it is in one direction and no other group present for canceling/decreasing its dipole moment.
• 2- In CH2Cl2 dipole moment of H-H atoms and Cl-Cl atoms do not cancel each other because angles are not 180° so they are not linear.
• 3- In CCl4 dipole moment cancel and becomes zero because the angle between trans position of Cl atom is 180°.
• Since more d cl more d dipole moment but in case of ch3cl here is max dipole-dipole moment because all d resultants r in the  same direction...in chcl3 resultant of two cl bonds cancel each other hn d remaining H nd Cl gives dipole moment
• The three-dimensional structures of the three compounds along with the direction of dipole moment in each of their bonds are given below:- CCl4 being symmetrical has zero dipole moment.
• In CHCl3, the resultant of the two C-Cl dipole moments is opposed by the resultant of C-H and C-Cl bonds.
• Since the Dipole Moment of the latter result is expected to be smaller than the former, CHCl3 has a finite dipole moment(1.03D)
• In CH2Cl2, the resultant of two C-Cl dipole moments is reinforced by the resultant of two C-H dipoles.
• Therefore, CH2Cl2(1.62D) has a dipole moment higher than that of CHCl3. Thus , CH2Cl2 has the highest dipole moment.