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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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2
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1answer
42 views

Why does dipole must lie parallel to a rotation symmetry axis?

While studying group theory, I've got confused by the following statement: For a molecule to have a permanent dipole moment, it must have an asymmetric charge distribution. The point group of the ...
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0answers
33 views

Why London force dominates in Alkyl Halides

Why London Force is greater than dipole-dipole interactions in Alkyl Halides? As we know that most of the time London force is weaker than other forces. Then why in this case it's not so? ...
3
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2answers
206 views

Link between centrosymmetry, dipole moment and chirality

What is the relationship between the three concepts in the title? I know all centrosymmetric molecules are achiral, but not all achiral molecules are centrosymmetric. Thus, there are no molecules ...
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0answers
48 views

Theoretically predict the density of water

Is it possible to predict the density of water having just its molecular structure (basically obtain 1 g/cm3 at 3.96 °C)? Are you aware of research/textbook that dive into this topic? Is it able to ...
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0answers
34 views

Do I understand correctly that simulation volume influences relative permittivity calculations? If so, how is the result useful?

I am having a lot of trouble understanding the influence of volume on relative permittivity/static dielectric constant. I'm not a chemist, but am using molecular dynamics to calculate relative ...
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0answers
27 views

Dipole moments of dibromoethene isomers

There was an exercise in my textbook asking to compare the dipole moments of 1,1-dibromoethene and 1,2-dibromoethene(Z). The answer in the textbook says that the dipole moment of 1,1-dibromoethene is ...
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2answers
120 views

Dipole moment of water using the definition [closed]

In many Chemistry books, the dipole moment of molecules is calculated through algebraic formulas. However, another definition of the dipole moment is $$\vec{\mu} = \sum_i q_i \, \vec{r}_i$$ So, how ...
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0answers
132 views

Comparing dipole moments of Ortho,para and meta compounds

I was doing some questions based on dipole moment ortho,met and para compounds. I was not able to understand why dipole moment for \ce{C6H4NH2NO2} increases from ortho to para Because i think \ce{NH2} ...
6
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0answers
152 views

Why is the dipole moment of XeF$_6$ zero? [duplicate]

In Concise Inorganic Chemistry by JD Lee (4th edition; adapted by Sudarshan Guha), page 73 under the section 3.6 (VSEPR Theory chapter Chemical Bonding): ...according to this theory, the position ...
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0answers
135 views

Why does the dipole moment order of group 15 hydrides increase down the group?

The order given in my book is $$\ce{NH3} > \ce{SbH3} > \ce{AsH3} > \ce{PH3}$$ Phosphorous is more electronegative than arsenic and antimony. Then shouldn't the dipole moment be more in ...
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0answers
45 views

Finding Bond moment of O-H bonds of water

While finding bond moment of water we take the dipole moment of water as the vector sum of two O-H bonds and we calculate it to be 1.51D. But the lone pair is also present which affects the dipole ...
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2answers
454 views

Why is the dipole moment of acetone higher than ethanol?

It is true that acetone is less polar than ethanol. I thought the dipole moment is proportional to polarity, and if so, the dipole moment of acetone should be lower than ethanol. But the dipole ...
3
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0answers
43 views

Why is there only little difference between molecular dipole moments in CHX3 compounds (X = Cl, Br, I)?

Why is there only little difference between molecular dipole moments in $\ce{CHX3}$ compounds ($\ce{X}$ = $\ce{Cl}$, $\ce{Br}$, $\ce{I}$)? As we can see there is a huge difference in dipole moment of ...
-1
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1answer
25 views

What is the meaning of moment in Dipole moment [duplicate]

Today I read about dipole moment in my standard textbook. It said something like it is the measure of charge separation, and then proceeded to the formula , ie. Delta'charge'×bond length. But I can't ...
0
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1answer
77 views

Why must polar molecules be asymetrical? [duplicate]

As I understand, polarity in molecules comes from the difference in electronegativity or the ability of the atoms to attract eletrons so the electrons spend more time or are more probable to gravitate ...
4
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1answer
111 views

Qualitative Comparisons of Dielectric Constants of Organic Solvents

This question is inspired by the discussion around this earlier question. It is relatively simple to do a qualitative comparison of the polarities of different molecules (for example by analyzing the ...
1
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1answer
63 views

dipole–dipole interactions: OCR Sample Paper wrong? [closed]

I was doing OCR A Level Chemistry A, H432/01 Periodic table, elements and physical Sample Question Paper. Question 6 was: The boiling point of hydrogen bromide is –67 ºC. The boiling point of ...
6
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1answer
378 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
31 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
79 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
231 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
188 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. ...
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2answers
220 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 ...
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0answers
382 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 ...
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1answer
76 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
186 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
56 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 ...
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2answers
1k 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 ...
4
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1answer
2k views

Why Benzene is a good solvent even while it is not polar

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
191 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
2k 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 ...
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1answer
103 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
948 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
102 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
152 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
126 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
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1answer
92 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
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1answer
178 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
508 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 ...
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1answer
412 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
231 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
185 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 ...
12
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2answers
986 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 ...
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0answers
487 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 ...
2
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0answers
11k 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
70 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
462 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 ...
7
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1answer
129 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 ...
3
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1answer
218 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
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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 ...