Questions tagged [polarity]

For questions about polar or non-polar chemical species, or their comparison. Also, for questions where polar or non-polar solvents have an effect.

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132 views

Dipole moment in NF3 versus NH3

The usual explanation for the molecular dipole moment of NF$_3$ being smaller than that of NH$_3$, despite the N-F dipole being stronger than the N-H dipole, is that influence of the lone electron ...
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1answer
38 views

Partial dissolution of non-polar solutes in polar solvents

I have learnt that in order for dissolution to occur, the solute-solvent intermolecular forces must be strong enough to overcome the solute-solute and solvent-solvent forces. However if this is the ...
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2answers
115 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 ...
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1answer
22 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 ...
2
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1answer
144 views

What is dielectric constant and how does it explain the reason why water is one of the best solvents

When i was reading solublity of ionic compounds,they mentioned that polar compunds are fairly soluble in polar solvents and water is better solvent due its high dielectric constant.Can anybody explain ...
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3answers
197 views

Is there a difference between dipole and dipole moment?

I’m confused as to whether both terms “dipole” and “dipole moment” are the same or different, does the moment have something to do with the molecular geometry? I know the vectors of the charges cancel ...
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1answer
74 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 ...
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1answer
95 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 ...
2
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1answer
37 views

How to determine polarity of components in TLC

Estimate how a TLC-analysis would look like for the following reaction when you take a TLC at: a) the start of the reaction, b) after 65% conversion and c) after full conversion of A. (You may assume ...
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1answer
79 views

Relation between ionic resonance energy and polarity

The ionic resonance of the bonds are given as follows: $$ \begin{array}{cr} \ce{A-B} & 24.3 \\ \ce{A-C} & 50.6 \\ \ce{A-D} & 102.3 \\ \ce{A-E} & 105.9 \end{array} $$ Which of ...
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1answer
75 views

Why is casein hydrophobic?

According to this source hydrophobic behaviour occurs when a molecule does not have a charge or is neutral and therefore cannot be attracted to the negative nor positive parts of water. Casein has an ...
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0answers
146 views

Why is Lithium Chloride (LiCl) soluble in alcohols?

According do J.D. Lee's Concise Inorganic Chemistry, LiCl is soluble in alcohols because it has some covalent nature, althought it is mainly polar. Why would LiCl have covalent character? Why doesn't ...
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1answer
114 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
77 views

Do molecules with polar bond, but with no dipole moment experiences a greater effect from the london dispersion forces?

Do molecules that have polar bonds and a structure that makes the polarity of those bonds cancel each other out, experience a greater effect from the London dispersion force, than molecules with a ...
2
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1answer
120 views

Comparing the bond strength between a polar bond and non-polar bond

According to NCERT class 12 part 2, $\ce{ICl}$ has lesser bond enthalpy than $\ce{I2}$. I have read that non polar covalent bonds are weaker than polar covalent bonds as in polar covalent bonds ...
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1answer
663 views

Why does a molecule with a Thiol group form Hydrogen bonds?

I'm doing the GRE Biology practice test, and question #1 asks: The answer is E. I understand why II and IV are polar, but why is $\ce{R-S-H}$ polar? R is a side chain to the sulfur, sulfur's valence ...
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1answer
417 views

Electrode polarity in fuel cells

I am studying fuel cells right now and I'm confused about the polarity of the two electrodes. In the diagram below, the anode is shown as negative. However, why do $\ce{H+}$ ions move away from the ...
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1answer
370 views

Why does the C-C bond break earlier than the C-F bond in the pyrolysis of perfluroethane?

According to me $\ce{C-F}$ bond is highly polar and thus is a weaker bond as compared to $\ce{C-C}$. Hence, $\ce{C-F}$ should break first in the pyrolysis of perfluroethane. Instead, in J. D. Lee, it ...
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0answers
78 views

Linalyl acetate: polar or nonpolar? [duplicate]

Why is linalyl acetate nonpolar? From the structure of the molecule I would have assumed that it was polar since it has a $\ce{C=O}$ bond and is asymmetric. What is it that makes it nonpolar?
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1answer
74 views

How does a mostly non-polar molecule prevent a polar head from being pulled off by other polar molecules?

Linear-shaped molecules of a solute with a large non-polar section and a small polar head are not soluble in a polar solvent. Why is this? Why don't the attractive forces between a molecule of polar ...
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0answers
443 views

Why is methamphetamine less polar then amphetamine? [closed]

The question is as stated in the title. Is there a general way to determine relative polarity of organic compounds? This question is for use in the context of the manner in which polarity of the ...
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1answer
627 views

Polarity and acid strength in alcohols

I'm totally confused about the relationship between the polarity and acid strength of a given compoud. Take the case of alcohols itself, it's said that primary alcohols have greater acid strength ...
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1answer
15k views

Halogenation of Phenol [closed]

Why does only one $\ce{Br+}$ ion get generated in a non-polar solvent (such as $\ce{CS2}$), while more $\ce{Br+}$ ions are generated in aqueous or polar solvent (such as $\ce{H2O}$)?
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400 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 ...
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0answers
866 views

Polarity of Acetic Acid, Ethanol and 1-Propanol

In order to compare acetic acid, ethanol and 1-propanol in terms of solubility in hexane, I would like to order them in terms of (a)polarity. By looking up the dipole moments, I found that these ...
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1answer
681 views

Why does an electron-donating group reduce the polarity of the O-H bond? [closed]

Why does the polarity of $\ce{O-H}$ bond decrease if an electron-donating group is attached in the compound? For example, I have seen that when alkyl groups are joined in phenols, the polarity of $\...
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2answers
2k views

Why does an OH bond absorb a higher frequency than a CH bond?

I'm wondering why a bond between an O and an H is going to absorb a higher frequency than a bond between a C and an H (any hybridization). O is heavier than C in terms of atomic masses, and I'm ...
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437 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 ...
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1answer
3k views

Why do chloroform and benzene exhibit negative deviation from Raoult's law?

Chloroform is a polar molecule, and benzene is nonpolar. Shouldn't the chloroform-chloroform and benzene-benzene intermolecular forces be stronger than chloroform-benzene interactions (like dissolves ...
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1answer
287 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?
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1answer
333 views

Affinity to mobile or stationary phase during column chromatography [closed]

I have carried a column chromatography and obtained two compounds. The first one is liquid (ester) and the second one is solid (nitro) yet I know that the second compound is less polar than the first ...
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2answers
800 views

Mechanism of Halogenation of Alkene

In the above reaction, we use a non-polar compound (such as CCl$_4$) as a solvent. Then, why does the Br$_2$ polarise on attack by the alkene, even though a non-polar solvent does not encourage ...
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0answers
110 views

What makes a bond non-polarisable?

Many chemical bonds are known to be polarisable. Similarly, many ions are also known to be polarisable. Examples include the carbon-iodine bond and the carbonate ion. Recently, I have read that the ...
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91 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 ...
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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 ...
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40 views

Ionic or Covalent? [duplicate]

Is BeF2 ionic or covalent? BeF2 : covalent or ionic? The above link does not provide a proper explanation as to why it should be ionic, even though fluoride anion is large and polarisable and ...
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362 views

Mixing solvents of different polarity [closed]

Suppose a non-polar solid is dissolved in ethanol. Water is added to the solution. Will the solid separate, if it isn't soluble in water?
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1answer
2k views

How does HCl dissolve in water if the intramolecular force is stronger?

So what I know now is that the H in HCl is more positive and the Cl is more negative, while the H in H2O is more positive and the O is more negative. When HCl enters water, its more positive atoms (H) ...
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3answers
5k views

What determines “polarizability” of an element?

In this question, the answer given discusses that fluorine has a good orbital overlap with hydrogen and also that fluorine is not very polarizable. However, is it always true that strong bonding is ...
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4answers
1k views

Easiest way (software) to visualize charge density from an .xyz file with point-charges?

I have an .xyz file which contains partial charges calculated by a Quantum-Chemistry software (NWChem). The system looks like this, here I show the partial charges calculated from the electrostatic ...
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1answer
1k views

Polarity of xenon fluoride

The structure of xenon fluoride is a capped octahedron. The lone pair is stereochemically active, i.e. it will rotate about. The dipole moments of the axial fluorides will get cancelled, and so will ...
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0answers
100 views

Why does increasing electronegativity difference result in decreasing density?

I've been collecting data and there's a very strong inverse relationship between electronegativity difference and density ($\pu{R^2}$ value of roughly 0.95 from my data). Is there any chemistry that ...
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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, ...
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1answer
658 views

Can I use gasoline as a non-polar solvent?

I was wondering if I can use gasoline for a non-polar extraction of organic substances instead of prescribed diethyl ether, which is a bit hard to get in my country. If not, are there any products ...
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0answers
402 views

Overall polarity of polychlorinated benzofuran

I have been struggling over this weekend to find an answer for the overall polarity of this molecule: 2,3,7,8-tetrachlorobenzofuran In order to find intramolecular forces, I determined the difference ...
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2answers
4k views

Why is sodium carbonate less soluble in water than sodium bicarbonate?

Why is sodium carbonate less soluble in water than sodium bicarbonate? If you think about their structures, the only thing that is different is that sodium carbonate has two sodium atoms, while sodium ...
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1answer
855 views

What causes polarization in noble gases?

According to my knowledge, polarization occurs when in a compound there is a difference of polarity its constituents. But in the case of noble gases, there is a single component. What exactly is ...
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4answers
10k views

Why are some molecules unable to absorb infrared radiation?

Methane $\ce{CH4}$ is symmetrical and non polar, and so is oxygen $\ce{O2}$. But $\ce{O2}$ doesn't absorb IR. Why is that? People say that if a molecule can change its polarity then it will absorb IR, ...
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1answer
229 views

Why is Cyanidine soluble in water?

Cyanidine is not polar due to its make-up of only hydrogen atoms and carbon atoms, correct? But "like dissolve like", which means it would HAVE to be polar, or no? Is it then soluble solely because of ...
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1answer
11k views

How to determine relative polarity (basic procedure)? [closed]

I am taking AP Chemistry, and have noticed that I can identify a polyatomic polar molecule, but struggle to determine which molecule is the most polar given a set of several polar molecules. What ...