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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Intermolecular Forces and State Change
I know that intermolecular forces determine the state of a substance at a given temperature and that changing state involves the ability of a substance to overcome those forces. I encountered a ...
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Fugacity vs compressibility
What's the criterion for saying that the forces of attraction are dominant?
f < p or Z < 1
I ask this because there is a situation where
f < p and yet Z > 1 (below Boyle temperature)
if ...
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What happens to the sea of electrons when a metal melts/boils? [closed]
I was taught about metallic solids with the sea of electrons model. My question is how does the sea of electrons function when metal turns into a liquid and a gas. The way I see a liquid is ...
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What are the intermolecular forces between the following compounds in a mixture?
I need to figure out the intermolecular force between the following compounds in a mixture:
acetone-aniline,
acetone-chloroform,
ethanol-acetic acid,
acetone-ethanol,
ethanol-water
Can someone ...
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Charge polarisation in acetamide molecule due to different lithium salts (varying anions)
I am trying to understand how will acetamide molecules behave in the presence of lithium salts with different anions (nitrate, bromide and perchlorate).
Among the three, it is evident that bromide is ...
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why Tin/Zinc alloys can be used to solder aluminum and Tin alone does not "wet" the aluminum?
It is impossible to solder aluminum with only tin, tin does not "wet" aluminum surface because of the instantaneous reaction aluminum/oxygen on the surface of the base metal (aluminum). I ...
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Why does the PE becomes negative in potential energy versus intermolecular distance graph? [closed]
In the potential energy versus inter molecular distance graph, we know that atoms/molecules/particles want to be at optimum distance from each other ie $r_0$ and to the left of this position in the ...
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Intermolecular forces between polyatomic ions and water
I was wondering what kind of intermoleuclar attraction exists between nitrate ion $\ce{NO3-}$ and $\ce{H2O}$?
Is it ion-dipole attraction or is it hydrogen bonding? Since there is nitrogen and oxygen, ...
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Do CHF3 and acetone form a hydrogen bond?
I haven't been able to find a reference confirming that fluoroform forms hydrogen bonds with acetone. Do they?
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Hydrogen Bond Length and Lattice Density [closed]
The subject of the density of solid water is discussed on Physics Stack Exchange in this post.
In the post, it is said that..
the way the molecule is angled ensures that a specific (energetically
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How to model a molecule of benzene surrounded by 100 molecules of water with molecular dynamics?
I have experience calculating molecular properties (mostly DFT). However, I would like to spend some time on molecular dynamics methods. I would like to ask your advice to direct me towards a program ...
user55257
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Differences between formulae for dipole–dipole interaction energy
I came across two formulae for dipole-dipole interaction energies on Chemistry LibreTexts — Dipole-Dipole Interactions:
$$V=-\frac{2\mu_1 \mu_2}{4\pi\epsilon_0r^3}\tag{3}$$
and
$$V=-\frac{2\mu^2_\...
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How are intermolecular forces between non-metallic substances affected when the substance is heated to its melting point?
I have 3 main questions that I am unsure of:
Are intermolecular forces acting simultaneously causing attraction between particles in a sample of a substance?
Example: Hydrogen bonding and dipole-...
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Intermolecular interaction Van Der Waals
In the empirical demonstration of the Van der Waals equation at Khan Academy, they made a demonstration of the real volume, for example, it was said that it has to be larger than the ideal volume, ...
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Why are Dispersion Interactions Stronger in Molecules with Bigger Molecular Mass? [duplicate]
Usually there are two explanations:
When dipoles are induced due to movement of electrons in the molecule, they are bigger in molecules with more mass since they have/include more atoms (has sense to ...
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Why do fluoride molecules seem to have abnormally low boiling points?
As far as I know, to non-polar molecules like CF4 and C2H6,
boiling point is mainly affected by the London dispersion force.
As a result, molecules with more protons and electrons normally have higher ...
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What does "the natural bond angle" mean in the context of Universal Force Field (UFF) potential energy calculation and how are bond angles calculated?
As the title says, what does "the natural bond angle θ0" mean in the context of Universal Force Field (UFF) potential energy calculation? The reference appears in section D. Angular ...
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Which definition of van der Waals forces is correct? [duplicate]
I've been told by my teacher that van der Waals forces is the formal name for intermolecular forces. But on the internet, many people are saying van der Waals forces is another name for London ...
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What are the limits of size differences in a host–guest complex?
We learn in my chemistry course that there must be a snug fit for a host-guest complex to form. So, something like benzene (0.6 nm in diameter) can form a host-guest complex with a β-cyclodextrin host ...
user107675
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Why does water weaken ion ion attractions?
My lecturer has told me that water, having a high dielectric value, will "shield" ions and reduce ion-ion attractions.
I really don't see why. Having water molecules surround these two ions ...
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Why are steric effects repulsive?
Normally, I think about orbitals interacting in the context of bonding. When two atomic orbitals overlap, they can do so in-phase or out-of-phase. The in-phase overlap results in a bonding molecular ...
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Magnitude of Lennard-Jones force evaluated with molecular dynamics simulation
The intent is to evaluate the error source of a molecular dynamics (MD) simulation which is only based on the Lennard-Jones interaction between noble gases (helium in this case). What is the magnitude ...
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Help understanding how "steric effects" are distinct from "electronic effects"?
@jakebeal's excellent answer to Why do animal cells “mistake” rubidium ions for potassium ions? includes the following passage:
In the case of potassium versus sodium, which are both very important ...
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Why do bubbles form and stay when I shake a bottle of tea?
I have some bottled tea and I noticed that shaking it creates some foamy bubbles that stay for quite a while (at least half an hour if not more). I originally thought it has something to do with my ...
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Strength of the hydrophobic interaction
How strong is the "hydrophobic force"?
Hydrophobic interactions are weak interactions but can have greater strength than hydrogen bonds. I find the strength of the hydrogen bond in ...
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Intermolecular forces of attraction between positional isomers of alcohols
This seemingly trivial question is as follows: Why is the boiling point of 1-butanol ($\ce {117.7 ^\circ C}$) higher than that of 2-butanol ($\ce {99 ^\circ C}$)?
The only reason I can think of is ...
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Why does Ethylene Glycol have higher boiling point than Propylene Glycol?
Looking at the two alcohols, both have hydrogen bonding and are singly bonded throughout the molecule. However, propylene glycol has a larger electron cloud which to my knowledge would increase its ...
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Why ethyl cyanide and propanol have the same boiling point?
As I understand, the intermolecular forces of ethyl cyanide are of van der Waals nature (dipole-dipole) but in the propanol molecule there are hydrogen bonds which are in principle much stronger. Why ...
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Can Steel be Created from Germanium?
I've tried searching with Google as well as on this website, but I haven't been able to find even a question asking about it. It was something that I was just curious about, but my limited knowledge ...
user101773
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Why hydrogen bonds are stronger than Van der Waals forces?
Why the hydrogen bonds are more intense than Van der Waals forces in the case where the molecules with the Van der Waals forces have a stronger dipolar moment than the molecules with the hydrogen bond?...
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Why are hydrogen bonds in an antiparallel beta sheet stronger than those in parallel beta sheets?
Beta sheets are illustrated as such in most diagrams, where:
In an antiparallel β-sheet, the polypeptide strands are arranged such that a $\ce{C=O}$ and an $\ce{NH}$ from adjacent strands face each ...
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Can we predict the IMF strength of Acetone vs Glycerol?
I was recently assigned a lab where I was to observe several properties of the chemicals Acetone and Glycerol then use my observations to predict their overall Intermolecular Force strength.
The ...
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Forcing atoms closer together [closed]
Is there a method in chemistry to alter the energy of atomic bonds by forcing atoms closer together in a smaller volume?
Similar to how pressure squeezes atoms closer together.
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Why does diethylmethylamine have such a low melting point?
According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^...
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Without attractive forces, why would there be only ideal gases? [closed]
I've read this statement in several places. What is the importance of attractive forces for solids and liquids?
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Relative strength of intermolecular forces [duplicate]
My attempt at a solution:
First I look for hydrogen bonds:
The only compounds with hydrogen bonds are the second and fourth ones, so they have the strongest intermolecular forces. The second must have ...
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Anomalous boiling point of "iso-" alkanes
I was attempting to compare the boiling points of iso-hexane and 3-methylpentane.
Boiling points of organic compounds depend upon three factors according to Master Organic Chemistry – 3 Trends That ...
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Why is carbon tetrachloride a liquid at room temperature? [duplicate]
From what I can understand, $\ce{CCl4}$ has only London dispersion forces between its molecules. However, it is still liquid at room temperature. $\ce{CCl4}$ has just five atoms, making it a ...
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work and chemical bonds [closed]
If breaking bonds is endothermic (takes energy), and work is force over a distance-
Would breaking bonds require "work"? Or do we only need heat energy? I'm trying to understand how to ...
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Casimir effect and van der Waals forces
The Casimir effect makes two close metal plates in a vacuum attract.
I was pondering and figured out that two close molecules should experience the same effect, as they are close and between molecules ...
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Why is boiling point of carbon tetrachloride greater than silicon tetrachloride?
$\ce{CCl4}$ and $\ce{SiCl4}$ both are non polar molecules thus London forces must be the only forces of interaction.
Then London forces are supposed to be greater in $\ce{SiCl4}$ due to its larger ...
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Do amines or alcohols have stronger intermolecular hydrogen bonds?
Which has stronger hydrogen bonding, $\ce{CH3OH}$ or $\ce{CH3NH2}$
I think it comes down to which has more dominance; number of hydrogens, number of lone pairs, or electronegativity.
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Atoms and their vibration [closed]
We all know that the atoms in any solid matter vibrate about their mean position but why do they do so?? What will happen if they stop vibrating??
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Ozone in ozone layer [closed]
If ozone is a gas, and gases have the highest entropy, then how does the ozone gas stay within a few layers of the atmosphere, even though they span for kilometers?
user92006
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Pressure of a system of particles
I'll derive the pressure of a system of particles, which would be used in a MD simulation for example, according to Allen's Computer Simulation of Liquids and show where my issue is.
Consider a ...
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it is possible for the hydrogen bond to form between the hydrogen chloride molecule, HCl? [duplicate]
Recently I'm doing my work, and I can't find what it is the answer. Can you guys help me?
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What are the cheapest basis sets able to model intermolecular dipole interactions inside a metal complex and give good relative energies, with DFT?
As a example, If I have a square planar complex of a cation with both a weakly polar ligand (X) and strongly polar ones, like ammonia and water I expect a bit of stabilization due to formation of a ...
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Why are Buckminsterfullerene (C60) solutions pink/purple?
A solution of Buckminsterfullerene $\ce{(C60)}$ is shown below:
According to the April 8th Wikipedia page on Buckminsterfullerene $\ce{(C60)}$:
Solutions of pure C60 have a deep purple color which ...
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Why is the boiling point of ethyl fluoride lower than that of hydrogen fluoride?
The book, Solomons' Organic Chemistry (for JEE Mains and Advance), contains the following question:
Hydrogen fluoride has a dipole moment of $\pu{1.82 D}$; its boiling point is $\pu{19.34 ^{\circ} ...
user88957
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Boiling points of ethylene, formaldehyde and oxygen
The boiling points of ethylene, formaldehyde and dioxygen are $\pu{-103.7 ^\circ C}$, $\pu{-19 ^\circ C}$, and $\pu{−183 ^\circ C}$, respectively. I expect formaldehyde to have the highest boiling ...
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