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Questions tagged [dipole]

For questions about the dipole moment of a bond or a molecule; its calculation, comparison with other bonds or molecules, affect on molecular properties, etc.

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1answer
36 views

Why are the dispersion forces in CS2 stronger than the dipole-dipole forces in COS?

London dispersion forces supposedly have the least strength out of all the intermolecular forces. But $\ce{CS2}$, which has only dispersion forces, has a higher boiling point (and thus stronger ...
2
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0answers
20 views

Perturbation theory for molecules, chromophore group, dipole approximation,

I am interesting in chromophore group and dipole approximation. For example, i have a molecule (acetone or any other ketone/enol) which is belongs to some symmetry group. Because of the symmetry ...
2
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1answer
36 views

Why does dielectric constant of crystal fluctuates in case of Frenkel defect in a crystal?

So I was studying Frenkel defect in crystal and came across this line that said The closeness of like charges tends to increase the dielectric constant of the crystal. I'm not able to understand ...
2
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1answer
102 views

Which has a greater dipole: chloroform (CHCl3) or trichlorofluoromethane (CCl3F)?

Does chloroform have a greater dipole because the $\ce{C-H}$ dipole is weaker than $\ce{C-Cl}$ dipole thereby making the overall net dipole greater in chloroform, as opposed to trichlorofluoromethane ...
0
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1answer
69 views

Why does phosphine have a dipole moment and a higher boiling point than carbon tetrafluoride?

Phosphine, PH3, and carbon tetrafluoride, CF4, are small molecules of a similar size and the same mass of 88 au. CF4 has a dipole moment of 0, which is unsurprising given its tetrahedral shape. ...
1
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2answers
116 views

Which Oxygen atom in HCOOH (formic/methanoic acid) does Carbon donate its electrons to, to obtain a partial positive charge?

I was wondering if the Carbon atom in HCOOH (methanoic/formic acid) forms a positive partial charge by donating its electrons to both the Oxygen atoms, since they both possess a higher ...
1
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0answers
201 views

Dipole moment in aromatic compounds

Compare the dipole moment of the following: o-nitrophenol o-dichlorobenzene o-xylene What I thought was: o-dichlorobenzene should have the maximum, due to the acute angle and being more ...
0
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1answer
52 views

how can a covalent molecule with a permanent dipole still have temporary dipoles?

As I have read online, temporary dipoles occur due to the random fluctuations of the electron cloud. The electrons move randomly to one side of the molecule creating a negative partial charge while ...
9
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2answers
117 views

Why is ammonia still considered polar despite undergoing rapid inversion?

Here it is stated that a molecule with a rotation axis cannot have dipole moment perpendicular to the axis, as any dipole moment would be changed upon rotation about this axis (which preserves the ...
2
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2answers
50 views

Directional emission from molecules

This might be a silly question (probably is). When a molecule absorbs it has a transition dipole moment, a measure of how strongly a certain transition will interact with light will depend on how ...
1
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2answers
707 views

Hydrogen bonds - why not in HCl? [duplicate]

In a textbook1, I found the following clear definition of hydrogen bonds: The strongest secondary bonding type, the hydrogen bond, is a special case of polar molecule bonding. It occurs between ...
1
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1answer
965 views

Why Benzene is a good solvent even while it is not polar [closed]

Consider for a moment, ether, THF, benzene and hexane. Why is the solubility of many organics in these solvents in the following order THF > ether / benzene > hexane What makes benzene a good ...
1
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1answer
181 views

Will there be change in electronegativity difference in C-O and C=O?

Is there any change in EN difference in C-O and C=O. If yes, why? Does EN difference change if its bond is changed to single, double, or triple?
8
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1answer
1k views

Why does C=O have a larger dipole moment than C-O?

Why does $\ce{C=O}$ have a larger dipole moment than $\ce{C-O}$? According to me, dipole moment directly depends upon bond length and electronegativity difference. In $\ce{C=O}$ and $\ce{C-O}$, (I ...
0
votes
1answer
95 views

What are the intermolecular forces between polychloroethylene?

Does polychloroethylene have only van der Waals/London forces between its molecules? Surely, if all the chlorine atoms are on one side, due to the fact that chlorine is more electronegative than ...
6
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2answers
587 views

How to compare dipole moment in thiophene, furan, and pyrrole?

This is what I found (source): I wonder about several things here. First, why is tetrahydrothiophene's dipole moment bigger than that of tetrahydrofuran, when considering that tetrahydrofuran has an ...
4
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1answer
94 views

Why does the helium hydride ion have such a large dipole moment?

According to Wikipedia, the helium hydride ion $\ce {HeH+}$ has a dipole moment of 2.26 or 2.84. What contributes to this large dipole moment in this molecular ion?
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0answers
108 views

Why don't I get the same value of percentage ionic character of a particular molecule from different equations?

About the ionic character of a polar covalent compound Pauling gave two equations as [1-$e^{.25(x_a - x_b)}] $% [18$(x_a-x_b)^{1.4}$]% Hanary and Smith gave the equation [$16(x_a-x_b)+3.5(x_a-...
2
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0answers
94 views

For a given period, why is the boiling point of the halogen greater than that of the noble gas?

The boiling point of bromine, a halogen, is $\pu{58.8^\circ C}$, while the boiling point of krypton, the noble gas in the same period as bromine, is $\pu{-153.4 ^\circ C}$. I thought that the larger ...
6
votes
1answer
85 views

Accuracy benchmarks for atomic multipole moments

Thermochemical accuracy is regularly quoted as 1 kcal mol$^{-1}$, or 4.2 kJ mol$^{-1}$. I'm expressing some data and I want to use benchmarks like this to validate them, however, they are not all in ...
8
votes
1answer
145 views

Does tetrachlorodibenzo-p-dioxin (2,3,7,8) have a nonzero dipole moment?

I've looked at and drawn the structure, and I originally felt that it would be nonpolar - as I believe all the dipoles would cancel out, but I'm not 100% sure. I might be too dependent on the fact ...
7
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1answer
369 views

Why does acetonitrile have a larger dipole moment and boiling point than acetaldehyde?

Experimentally, acetonitrile has a larger dipole moment than acetaldehyde, but I've never understood why. I always thought that the charge separation between carbon/oxygen is larger than that of ...
-2
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1answer
371 views

London Dispersion Forces and Dipole-Dipole forces together? [closed]

How do London Dispersion Forces and Dipole-Dipole forces exist at the same time between polar molecules?
5
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1answer
189 views

Relative importance of electronegativity and bond length for dipole moment magnitude

In this answer to the question "Why is the dipole moment of chloromethane larger than the dipole moment of fluoromethane?", the order of the dipole moments was given as $\ce{CH3Cl > CH3F > CH3Br ...
13
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1answer
147 views

Are there any (simple) molecules with very different absorption and emission dipole directions?

When a single molecule absorbs or emits light, it does so perpendicular to the direction of the respective transition dipole. In principle, the directions of the dipoles for absorption and emission ...
13
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2answers
686 views

How to identify hydrogen bonds and other non-covalent interactions from structure considerations?

Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically ...
0
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0answers
346 views

Deciding if a molecule is polar and non-polar in cyclic carbon compounds

While discussing about dipole moment of the compounds, our chemistry teacher told that the dipole moment will be 0 for 1,4-Dichlorobenzen, and for those compounds where same atoms or group of atoms ...
3
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0answers
4k views

Order of dipole moments of chlorine substituted methane (CH3Cl, CH2Cl2, CHCl3, CCl4) [duplicate]

In my book, the order of dipole moment for CH3Cl, CH2Cl2, CHCl3 and CCl4 is given as: CH3Cl>CH2Cl2>CHCl3>CCl4 The way I understand this is— In case of CCl4, tetrahedral symmetry exists. Therefore,...
0
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1answer
64 views

Dipolar moment between HI and HF [duplicate]

Which between $\ce{HI}$ and $\ce{HF}$ has a greater dipolar moment? I think it is $\ce{HI}$ because the atomic radius of $\ce{I}$ is greater.
11
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2answers
405 views

Hartree-Fock dipole moment

I read this sentence in a paper (J. Phys. Chem. A 2014, 118 (20), 3678–3687. DOI: 10.1021/jp502475e): Calculations using Hartree–Fock theory systematically overestimated dipole moments and ...
8
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1answer
124 views

How real are bond dipoles?

In general chemistry, it is common to teach students to determine a molecular dipole by having them first determine "bond dipoles" which are just based on electronegativity. Then, by adding up these ...
4
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1answer
157 views

Theoretical comparison of dipole moments of N,N-dimethyl-4-nitroaniline and N,N,2,3,5,6-hexamethyl-4-nitroaniline

These two compounds are given in my workbook, and I am supposed to compare their net dipole: The solution given in the workbook is that: Molecule A (N,N-dimethyl-4-nitroaniline) has a "net shifting ...
5
votes
1answer
1k views

Dipole moment of ferrocene conformations

Which conformation of ferrocene has a zero dipole moment? I thought that the answer should be the staggered conformation because it would have the cyclopentadienyl groups oriented away from each ...
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1answer
276 views

Polarity of symmetric Lewis structure [closed]

Why is $\ce{CF2Cl2}$ polar? The Lewis dot structure shows the molecule as being symmetric. Wouldn't that make it nonpolar?
7
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1answer
902 views

Calculating dipole moments from atomic partial charges

How can I calculate dipole moment of a complex molecule where the partial charges are available from density functional theory? I have the coordinates of each atom from atomistic simulations of an ...
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0answers
80 views

Why is the molecular dipole the main determinant of whether a substance dissolves in another substance?

Consider a covalent molecule such as carbon tetrafluoride. In $\ce{CF4}$, each $\ce{C-F}$ bond is polar covalent. However, this substance is considered overall non-polar because each bond dipole ...
12
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2answers
5k views

Does the dipole moment increase or decrease by increasing the bond length?

It is established the dipole moment is a result of multiplication of the magnitude of charges (Q) and the distance between them (r). What I understand is that when an electron and a proton get closer (...
4
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2answers
4k views

Why does acetone have a greater dipole moment than dimethyl ether?

Below are the lewis structures for dimethyl ether and acetone. My chemistry textbook indicates that acetone has a larger dipole moment than dimethyl ether. I am familiar with dipole moments and the ...
5
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0answers
66 views

Program to compute multipoles of water at CCSD(T)-F12 accuracy

I want to compute traceless cartesian electrostatic multipole moment tensors up to fourth order (hexadecapole), at CCSD(T)-F12 accuracy using a large basis set. I'd like to be able to choose the ...
3
votes
1answer
3k views

Why does p-dichlorobenzene have zero dipole moment while hydroquinone does not?

At first I thought that both the OH groups would cancel out their dipole moments in hydroquinone. On reading further, I realized that because of the two different planar structures possible, it has a ...
1
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0answers
94 views

Closed shell structure & intrinsic molecular (electric) dipole moment

Does the closed shell structure of a molecule imply that it has an intrinsic (electric) molecular dipole moment? If so, why is that? I came across this in paper [1], which seems to suggest that this ...
4
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1answer
536 views

Why bond energy of acetone is more though it is more polar than formaldehyde?

I was going through the general properties of carbonyl compounds and then found this (in the pic) data, where it says that dipole moment of acetone (if we assume $\ce{R = -CH3}$) is more than ...
14
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2answers
1k views

Why are dipoles “permanent/induced dipole permanent/induced dipole” and not just “permanent/induced dipole” once?

My teacher would always say "induced dipole induced dipole" and while it annoyed my slightly (as you were saying the same word twice) it didn't really bother me, ...
6
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1answer
195 views

How do atoms lose their induced dipole?

There exists the basic chemistry lesson with induced dipoles where the electron density of one atom changes causing a dipole to form and causing a cascading effect where other atoms adjacent to that ...
3
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1answer
711 views

Is dipole moment a vector?

Isn't it a misconception to assume that dipole moments are similar to vectors in their behavior? My reasons are as follows: Let us take an example: Methane ($\ce{CH4}$) Clearly, the hydrogen atoms ...
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0answers
461 views

What is the need for dipole moment if electronegativity already exists?

Say we have an HCl molecule. The difference in electronegativities of the H and Cl atoms tells us how polar the HCl molecule is. The dipole moment is also a measure of the degree of polarity in ...
4
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2answers
1k views

Dipole moment of borazine

What is the dipole moment of borazine? I tried googling it but can't find a reliable source. I searched in JD Lee too. It might have it but I could not find.
2
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2answers
8k views

Dipole moment of CH2Cl2 and CHCl3 [duplicate]

Why does $\ce{CH2Cl2}$ have a higher dipole moment than $\ce{CHCl3}$? My argument being that the $\ce{CCl3-}$ ion being rather stable, can generate a good amount of polarity in the bond, moreover, ...
13
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4answers
1k views

What is the exact reason that compounds such as carbon dioxide cannot interact with other compounds through dipole-dipole interactions?

Whilst I understand that $\ce{CO2}$ has a linear structure, resulting in a vector sum of the dipoles of 0, I do not understand why the dipoles formed at the two oxygen atoms as a result of their ...
11
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1answer
1k views

Why is the dipole moment of chloromethane larger than the dipole moment of fluoromethane?

On the Pauling electronegativity scale, fluorine and chlorine are 3.98 and 3.16, respectively. Since the dipole moment is dependent on electronegativity, why is the dipole moment of chloromethane ...