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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.

Polarity is the separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment.

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Why is water "the universal" solvent?

This is an old question that our textbook tried to answer but worsened the situation. Many things are soluble in water. So many, that studying solutions will always require studying aqueous ones. It is true that many non-polars like waxes are not…
M.A.R.
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Why is water a dipole?

Water ($\ce{H2O}$) is a dipole. The reason why is simply because it is not symmetrical, there are more electrons on the oxygen side than on the hydrogen side, and the electronegativity of oxygen. But why isn't $\ce{H2O}$ symmetrical like $\ce{CO2}$?…
Friend of Kim
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Non-zero dipole moment of hydroquinone

Why does hydroquinone possess a non-zero dipole moment? The $\ce{OH}$ groups present at para positions on the benzene ring should cancel the effect of each other... if there is a plane change then exactly when do atoms in a molecule change planes?
Napster
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Why is the boiling point of fluorine lower than that of oxygen?

Fluorine boils at -188.1 °C and oxygen boils at -183 °C, but shouldn't $\ce{F2}$ boil after $\ce{O2}$? Despite being electronegative elements, both are nonpolar molecules and posses dispersion forces as the only mean of intermolecular interactions.…
John Hon
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Dipole moment of cis-2-butene

I need someone to back me up on this before I go confront my teacher: I was doing some analysis of the dipole moment of cis-2-butene. Let's say that the alkyl groups are both on top. Would the dipole moment be a vector that has its tail on the top…
yolo123
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Quadrupole moment of a molecule

What is a quadrupole moment of a molecule and how does it arise? How is it measured for a particular molecule? I've read the Wikipedia article on quadrupoles and understand that it has to do with the distribution of charge, but I'd like a more…
EJC
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Is the triiodide ion polar?

Three professors argue it is non-polar. My professor argues that it is a monopole, like most ions. The structure of the triiodide ion places a negative formal charge on the central iodine atom. The molecular geometry is also linear (at least…
Dissenter
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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 surface potential (using CHELPG method). I want…
khaverim
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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, but now looking through some exam papers it's called the same thing "induced dipole…
Crafter0800
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Why is carbon dioxide nonpolar?

I understand that polarity corresponds to an electronegativity difference and that the larger the electronegativity difference, the more polar the bond. However, I have read that carbon dioxide is nonpolar. This doesn't make sense to me. In carbonyl…
Caters
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Why are bonds ionic when the electronegativity difference between bonded atoms is greater than 1.7?

I'm learning about how to recognise whether a bond is ionic or covalent, based on the difference in electronegativity between the two bonding partners, $\Delta \chi$. What I have now is a formula: If $\Delta \chi = 0$, then the bond is nonpolar If…
LeDuc
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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, but I don't understand how a molecule changes…
user41793
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Why are alcohols with longer chains less polar?

In my self-study, I recently came across the following question: "Choose the solute of each pair that would be more soluble in hexane ($\ce{C6H14}$). Explain your answer. (a) $\ce{CH3(CH2)10OH}$ or $\ce{CH3(CH2)2OH}$ ..." Undecanol is more soluble…
readyready15728
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Difference of dipole moments of dichloromethane and trichloromethane?

Why is the dipole moment of $\ce{CH2Cl2}$ ($1.60 ~\mathrm{D}$) greater than that of $\ce{CHCl3}$ ($1.08~\mathrm{D}$)? Based on my knowledge of vectors, I feel it should be the other way around.
Apurv
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Why is DMSO more polar than other solvents, yet it dissolves ionic compounds worse?

I'm working right now in the solvent importance in ionic character, and I noticed how a binary salt ($\ce{CuCl2}$) dissolved better in methanol than in dimethylsulfoxide, and in contrast, a coordination compound (Cu[salen]) dissolved better in DMSO…
Farad
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