Questions tagged [intermolecular-forces]
The forces, either attractive or repulsive, that exist between molecules due to electric charges or varying electron cloud distribution. This tag could also include intra-molecular attractions (within one molecule itself) often found in a protein amino acid residues.
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Dipole vs Dispersion Forces
Sometimes dispersion forces can outweigh dipole interactions given that it is sufficiently large. Some large enough nonpolar molecules have a higher boiling point than small polar molecules. At what ...
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Does glucose form a molecular lattice in the solid state?
When I look at solid iodine, it is a molecular lattice held by van der Waals forces. Glucose is also simple molecular and so I naturally assumed that because it is solid like iodine, it forms ...
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Cucurbiturils and cyclodextrins — what is the difference?
One was reading about the cyclodextrins on this site and decided to further investigation on the matter. One encountered a class of molecules called cucurbiturils, which are macrocyclic molecules that ...
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Why do we not consider the force of repulsion between two cations/anions in an ionic lattice?
Obviously, there are forces of attraction between the Cl- anions and the Na+ cations. But aren't there also forces of repulsion between the Na+ atoms (look diagonally between the grey atoms)? Likewise ...
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Are van der Waals forces the same thing as intermolecular forces? [duplicate]
Like the name suggests, intermolecular forces are those between molecules and can be forces of attraction between permanent dipoles or temporary dipoles. However, it seems that the definition of van ...
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Cyclodextrins: Is there really a hydrophobic interior and hydrophilic exterior?
I do not get most of the explanations on why cyclodextrins are so good at hosting hydrophobic molecules. It is true that the hydroxyl groups are pointed outwards and thus the cavity is definitely less ...
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London forces and van der Waals interactions
London or dispersion forces are considered to be type of van der Waals (vdW) interactions or inter-molecular forces that are neither ionic or covalent. However, is there way to distinguish dispersion ...
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Complexities in Long-Term Storage Container-Planning for DIY Ferrofluid Experiment
I’m a big 2-part resin crafter, so my question pertains specifically to the interactions between ferrofluid and resin.
I recently acquired a large glass tube with open ends and I’m trying to figure ...
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Melting Point Order of Benzene Derivatives
Q)Compare the melting points of the following?
o-Hydroxybenzaldehyde
o-Methoxybenzaldehyde
p-Hydroxybenzaldehyde
p-Methoxybenzaldehyde
My attempt: Intermolecular H-bonding increases melting point ...
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Are London dispersion forces in xenon tetrafluoride strong enough to make it a solid?
Xenon_tetrafluoride ($\ce{XeF4}$) is a well-known square-planar molecule with no dipole moment. Molecules are thus have to be bound to each other by London dispersion forces (LDF) which are known to ...
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A curly arrow can only have its tail starting from a double bond or lone pair?
According to this video, a curly arrow representing a reaction mechanism can only have its tail starting from a double bond or a lone pair.
I am wondering if the tail of a curly arrow could also start ...
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Why is hydrogen bonding stronger than dipole-dipole interaction of carbonyls? [duplicate]
My understanding was that hydrogen bonding is much stronger than other dipole-dipole interactions since the dipole between hydrogen and O/F/N is much greater than other dipoles. However, the dipole ...
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What explains the relative order of melting and boiling of oxygen and nitrogen?
Why is the melting point of nitrogen ($\ce{N2}$) greater than that of oxygen ($\ce{O2}$)? After all, both are non-polar, and $\ce{O2}$ has more electrons than $\ce{N2}$.
In addition, why is the ...
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How would you explain the general trend in melting point between Group 1 and Group 2 chlorides?
This question is based off of the attached chart. I notice how there's a general increase in melting point down group 2 chlorides and a general decrease (except for Lithium) down the group 1 chlorides....
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Is a microplastic saturated ferrofluid polar or nonpolar? [closed]
In my experiment (Junior science fair) I submerged a magnetic chip collector holding my ferrofluid (magnetite and grape seed oil) with polypropylene beads (attracted as part of the experiment) into ...
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How do pencil erasers erase on a fundamental level? [duplicate]
One could say we're taking advantage of friction, but I want to dig deeper down to molecular/atomic level: what's the process or chain that happens when one erases from a macroscopic to a more ...
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Potential Energy Function for Two Atoms
The potential energy between two atoms, in a molecule, is given by
$$U(x)=\frac{a}{x^{12}} -\frac{b}{x^6}$$ where $a$ and $b$ are positive
constants and $x$ is the distance between the atoms. The atom ...
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Why does fluorine form only one hydrogen bond, but oxygen forms two?
Oxygen forms two hydrogen bonds as it has two lone pairs. So, why does fluorine only forms one hydrogen bond having three lone pairs?
Both oxygen and fluorine have nearly the same size, so steric ...
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Why does AsH3 have a higher boiling point than HBr?
Aside from the general trend of the boiling points of the hydrides, I noticed how the group 15 hydrides somehow "overtook" the group 17 ones in boiling point, which felt weird.
Notably, H-...
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How to calculate the ground state molecular potential curve of Lithium in different spin configuration?
I am a physics student and interested in Atom, and molecule optical physics. I am studying Feshbach resonance and I need to know the potential curve of the molecule, then I ask question in physics ...
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Why is octane more volatile than water while having a higher boiling point?
Octane has a boiling point of 120 °C. Water has a boiling point of 100 °C. The definition of boiling point is, "the temperature which the liquid substance's saturated vapor pressure equals the ...
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What is the effect of dissolving ammonia in water on hydrogen bonding?
Hydrogen bonding exists between $\ce{NH3}$ molecules. When $\ce{NH3}$ is dissolved in water, I know that hydrogen bonds are formed between $\ce{NH3}$ and $\ce{H2O}$ molecules. However, do the $\ce{NH3}...
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Why does N,N-dimethylethanamide have a higher boiling point than butanoic acid?
According to Wikipedia, N,N-dimethylethanamide has a boiling point of $\pu{165.1 °C},$ while butanoic acid has a boiling point of $\pu{163.75 °C}.$
From what I learned, butanoic acid should have a ...
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Why so many intermolecular forces?
I was recently learning about intramolecular and intermolecular forces. It seems there are a variety of interactions ( Dipole-Dipole. Ion-Dipole etc ). Why must this be the case? Couldn't all chemical ...
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Why does Methanol have a higher surface tension than Ethanol? [closed]
I am researching the surface tension of different alcohols and found something odd: the surface tension of Methanol was higher than that of Ethanol, which doesn't make sense to me. My understanding is ...
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Is there experimental evidence to show boiling point increases with external electric field, and if so, by how much?
I was wondering whether anyone has demonstrated that a liquid will have a higher boiling point if it is placed in a very large electric field. I believe to be the case, since induced dipoles would be ...
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Air/Acetonitrile Interfaces
Say I drop some acetonitrile on a grounded surface and it forms a meniscus. The acetonitrile is in air. Lets forget about evaporation for the moment.
Will there be an interfacial dipole formed by the ...
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Why surface tension acts tangentially if there is a net inward force? [closed]
I understand that surface tension is caused by an imbalance of forces for molecules on the surface in comparison to those that lie within. As a result, this creates a net inward force that seeks to ...
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Why is the van der Waals constant b of NH3 less than that of N2?
According to the actual data, van der Waals constant $b$ of $\ce{NH3}$ gas is $\pu{0.0371 L mol-1}$ and that of of $\ce{N2}$ gas is $\pu{0.0387 L mol-1}$.
But it should be,
$$b_{\ce{NH3}}>b_{\ce{...
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Hydrogen bond in water vapor [closed]
As the temperature increases and liquid water changes to gas, are ALL the hydrogen bonds broken or they are just weaker?
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Is it possible to have an anhydrous solvent for virology, specifically in vitro phage assembly?
Typical protocols for lambda phage in vitro assembly call for you to dump all your viral components and buffer solutions into water. Water is a great solvent, drives extraction of energy from atp, and ...
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Why do some hydrates need to be heated over 100 Celsius to evaporate the water?
If the boiling point of water is at 100 °C, why does a hydrate need to be heated higher than that to evaporate water from the crystals? Does it have anything to do with their intermolecular forces?
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Is there any material that, subjected to electricity, extends in size in multiples without substantial change in heat for human use? [closed]
Is there any material that can molecularly restructure so as to expand its intra- or inter-molecular distance by no less than three-fold without substantially losing its structural integrity and ...
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Analog of chemical accuracy in vibronic energy calculation [closed]
Is there any analog of chemical accuracy in vibronic energy calculation? I understand that the unit is /cm however, probably, I shouldn't expect a given number in that unit as the analog.
I am ...
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When does a long carbon chain become more significant to the boiling point of a substance than polarity? [closed]
I'm asked to sort the following compounds according to their boiling point (in an increasing manner): acetic acid, sodium chloride, and pentadecane (C15H32). Obviously, sodium chloride will have ...
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Are all humectants sticky?
While using a topical lotion based on ethanol, water and propylene glycol, I noticed that it becomes sticky while drying. Propylene glycol is a humectant and is used for this purpose in ...
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Why do atoms make bonds? [duplicate]
I have been studying chemistry for a long time in school till now, but, what I recently realised I do not understand is why do atoms really make bonds, why do they want to gain or lose electrons or ...
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Why does alkylamines have a higher boiling point than ammonia?
Here are the boiling points of ammonia and some amines:
$$ \begin{array}{|c|c|}
\hline
\textrm{Substance} & \textrm{Boiling Point} \\
\hline
\textrm{Ammonia} & \pu{-33.34^\circ C} \\
\textrm{...
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Resource estimate for ab initio calculation [closed]
I have recently come across this very intriguing paper “The Fundamental Vibration of Molecular Hydrogen”.
I have asked the authors the following naïve questions directly via email?
What was the ...
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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 ...
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Interaction energy of an hydroxide ion with a Pd surface
I need to estimate the interaction energy of a hydroxide ion with a palladium surface of $-0.6$V in water.
I know that the electric field of a charge $e$ is
$$
E = \frac{1}{4\pi\epsilon}\frac{e}{r^2}
$...
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Viscosity and repulsive forces
Suppose we let a ball move in a fluid with initial velocity $u_i$. Then as time goes on its velocity goes down and tends to $0$ after infinite time. I understand viscosity in the following way:
In ...
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Comparison of hydrogen bond strength
Consider the following sets of H-bonds:
$$
\begin{align}
&\text{P:} &\ce{-O-H\bond{....}N} \\
&\text{Q:} &\ce{-O-H\bond{....}O} \\
&\text{R:} &\ce{-N-H\bond{....}N} \\
&\...
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Incompatibility of Helmholtz Double Layer and Redox electrochemistry
In an electric double layer capacitor(EDLC) (or any situation with a Helmholtz double layer) what prevents the ions from being reduced or oxidized like the ions in an electrochemical cell?
If it is ...
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Exceptions to the molar mass trend in London dispersion forces in molecules: do they exist?
"In general, larger molecules have higher boiling points than smaller molecules of the same kind, indicating that dispersion forces increase with mass, number of electrons, number of atoms or ...
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Physical origin of induction and dispersion energies
I am reading this book on non-covalent interactions. Chapter 1 states that there are 3 types of non-covalent interactions:
Electrostatic interactions, which are just the coulomb interactions between ...
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Can Ion-Dipole Force Occur Between Lecithin and Water?
So, ion-dipole force occurs between an ion and a polar molecule. I would like to ask if an ion-dipole force would occur between water molecules and lecithin as seen in the picture, since it has a ...
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How is relative interaction energy defined and quantified?
I understand the interaction energy is the energy associated or caused by the interaction between the objects. So, for atoms it has to be the sum of van der Waals interaction and Coulomb interaction.
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Should there be a better explanation on Van Der Waals force? [duplicate]
The explanation on how Van der Waals force forms is this: Van der Waals forces consist of induced, temporary dipoles between neighbouring molecules. These are caused by constantly shifting electron ...
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What does Partial charge means in Dipole Dipole forces [duplicate]
Dipole-dipole forces act between the molecules possessing permanent dipole. Ends of the dipoles possess “partial charges” and these charges are shown by Greek letter delta (δ). Partial charges are ...
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