31 votes

Why is the boiling point of fluorine lower than that of oxygen?

It would be tempting to argue that fluorine is so electronegative and holds its electrons so tightly that their polarizability is reduced, thus so are the dispersion forces in $\ce{F2}$. But upon ...
Oscar Lanzi's user avatar
19 votes
Accepted

Quadrupole moment of a molecule

What is a quadrupole moment of a molecule and how does it arise? This explanation is geared at someone with one year of chemistry. It captures the gist but is not rigorous: To test for monopoles, ...
Karsten's user avatar
  • 40.2k
17 votes
Accepted

What happens if you carbonate ethanol?

Carbon dioxide is in fact roughly ten times as soluble in ethanol as in water [1](https://doi.org/10.1016/j.fluid.2006.04.017) (meaning you need more dissolved under pressure to get that bubbling ...
Oscar Lanzi's user avatar
14 votes
Accepted

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

Because it takes two to tango. Dipoles interact with each other. A Lone dipole has nothing to interact with (other than an electric field, but if we ignore some externally applied macro field, there ...
matt_black's user avatar
11 votes

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

As the other answers have indicated, CO2 has no NET dipole moment. However it does have two dipoles pointed in opposite directions (as OP keeps mentioning). This means that CO2 can possibly interact ...
user157879's user avatar
11 votes

Why are some molecules unable to absorb infrared radiation?

In basic terms, for a molecule to absorb radiation there has to be an oscillating dipole being produced. This can occur by nuclear motion (vibrations, rotations) or electronic motion to produce ...
porphyrin's user avatar
  • 30.4k
10 votes

If the polarity of the solvent increases, will the Rf value increase or decrease?

I wish we would stop teaching chromatography in terms of "polar" and "nonpolar." The aspirin will interact fairly strongly with the silica due to hydrogen bonding/electrostatic interactions of the ...
SendersReagent's user avatar
9 votes

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

Carbon dioxide is more than linear. It's symmetric, and the axis of symmetry perpendicular to the bonds also applies to whatever dipole moment it has. The only vector that looks the same after being ...
Zhe's user avatar
  • 17.4k
9 votes

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

After the successful calulation of the electrostatic surface potential, molden equally allows the display of it in a form like (source) A step-by-step, hopefully still functional, tutorial is this. ...
Buttonwood's user avatar
  • 29.7k
9 votes

Halogenation of Phenol

The reaction of phenol with bromine is known as bromination of phenol. Solvent has great influence on the reaction. In different solvents, different products are obtained. The action of bromine on ...
Uday's user avatar
  • 330
8 votes

If the polarity of the solvent increases, will the Rf value increase or decrease?

Since aspirin has a carboxylic acid group on it, it would be considered polar. Silica gel, consisting of $\ce{SiO2}$, is also polar. Since polar molecules attract other polar molecules, the aspirin ...
ringo's user avatar
  • 24k
8 votes

How can sulfate be nonpolar covalent if it is a polyatomic ion?

These two species have bonds within them, and (non)polar covalency refers to those internal bonds. The species as a whole can be an ion, and yet not have net polarity on its bonds. Sulfate is ...
NMJD's user avatar
  • 673
8 votes
Accepted

Polarity index vs. Dipole moment

From Roger E. Schirmer "Modern Methods of Pharmaceutical Analysis": Solvents are generally ranked by polarity, but polarity is not a uniquely defined physical property of a substance. Hence the ...
CoffeeIsLife's user avatar
  • 4,284
8 votes

Reaction of water and methane

Polar and non-polar liquids do not mix, but that doesn't tell you anything about their ability to react, which depends on the thermodynamics and kinetics of the reaction. The reaction shown is in the ...
NMJD's user avatar
  • 673
8 votes

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

Exactly that. Dipole-dipole interactions are caused because the positive end of one dipole is attracted to the negative end of another dipole. This macroscopic attraction can only occur if the centre ...
Jan's user avatar
  • 68k
8 votes
Accepted

Polarity of alcohols and their miscibility in water

If your book says exactly that, then it says nonsense. Sure enough, the addition of CH2's makes a molecule less polar. As for the solubility in water, methanol is miscible - i.e., infinitely well ...
Ivan Neretin's user avatar
  • 31.2k
8 votes

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

I have found one simple way to do this via Molden: Open the .xyz file via Molden: gmolden myfile.xyz Click the "Create Surfaces ...etc." button Click Solv. Acc. ...
khaverim's user avatar
  • 3,610
8 votes

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

I think this qualifies as a separate answer, using VMD. I converted the .xyz file to .pdb format (or at least some variant of the strict convention). Thus the file looks like below. The columns are ...
khaverim's user avatar
  • 3,610
8 votes
Accepted

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

I think, the easiest way is to use Multiwfn in combination with Jmol. There you can estimate/rebuild the ESP from partial charges. Multiwfn Load your xyz file with the charges into Multiwfn, which ...
pH13 - Yet another Philipp's user avatar
8 votes
Accepted

Hartree-Fock dipole moment

I originally wrote this as a comment, but I will post it as an answer as I'm fairly certain this is most of the answer. In general, there are two distinct types of electron correlation which can be ...
jheindel's user avatar
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8 votes
Accepted

Possible structure if a compound like AB4 is polar?

Given all $\ce{B}$ are equivalent in terms of AXE notation, for $\ce{AB4}$ the following coordination environments are possible [1, p. 177]: square-planar $(D_\mathrm{4h},$ SP-4); square-pyramidal $(...
andselisk's user avatar
  • 37.6k
8 votes

Does an ionic bond have a dipole?

"A dipole" strongly implies a single thing having two poles. A molecule, like for example HCl, is a single thing. It consists of two atoms sharing a privileged spatial relationship, that ...
Randy Lambreghts's user avatar
7 votes
Accepted

Which has more inductive effect: an aldehyde or a carboxylic acid?

I believe the Wiki page is more accurate, because the Hammett Equation substituent constants (para) indicate -CHO should be more "electron withdrawing" than -COOH, but there is little reason to use ...
Zachr's user avatar
  • 308
7 votes

What determines "polarizability" of an element?

Fluorine is not very polarizable because it is small. Its electrons, therefore, are all close together. A polarized atom has shoved all its electrons to one side. Since they are close together in ...
iammax's user avatar
  • 1,009
7 votes

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

This is because when these liquids are mixed, H-bonding type interactions are formed between hydrogen atom of chloroform (partial positive charge due to 3 Cl atoms) and 'pi' electron cloud of benzene ...
Apurvium's user avatar
  • 1,272
7 votes
Accepted

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

I got this explanation from one of my seniors. It is true that $\ce{C-F}$ bond is highly polar as fluorine is more electronegative than carbon. In fact it is this very difference in electronegativity ...
Hercules's user avatar
  • 709
7 votes
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Qualitative Comparisons of Dielectric Constants of Organic Solvents

Yes, but it is much more complicated. The molecule does not have to have a dipole, in which case the (static) dielectric constant (relative permittivity) depends on the molecule's polarisability and ...
porphyrin's user avatar
  • 30.4k
7 votes
Accepted

Question about the role of d-orbitals in polarisation

Well, please be more specific about the molecule(s) in question for that quotation. d-orbitals are certainly involved in some bonding, especially for the transition metals, but you are right that the ...
ketzbook's user avatar
  • 116
7 votes

Can “hydrates” of crystals form with other molecules?

An examplle used for disinfection and synthesis is the compound of urea with hydrogen peroxide, $\ce{CO(NH2)2•H2O2}$. This is a shelf-stable source of hydrogen peroxide that readily releases the ...
Oscar Lanzi's user avatar
6 votes
Accepted

In practice, do polar molecules actually align in an electric field?

These are two entirely different and unrelated phenomena, to the point that you'd better unsee that other question and my answer to it, if you can. Ions are very much not like molecules. Ions are ...
Ivan Neretin's user avatar
  • 31.2k

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