Skip to main content

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.

Filter by
Sorted by
Tagged with
0 votes
1 answer
110 views

Intermolecular Forces of Attraction [closed]

Imagine a bottle 85% filled with water and the rest is just air, and the cap is closed. Here are now my questions. Since the cap is closed completely, the air bubble is formed. Is that air bubble ...
Deepalya Jha's user avatar
1 vote
0 answers
1k views

Solubility of alcohols in non-polar solvents

The solubility of an alcohol in a non-polar solvent (like hexane) increases with size of the alcohol, as the non-polar chain increases. However, as the chain keeps increasing, will the solubility ...
tt123's user avatar
  • 51
-2 votes
1 answer
49 views

How big does an atom need to be to have dispersion forces be greater than other intermolecular forces? [closed]

I know as an atom gets bigger the dispersion forces grow with it. But how big does an atom, e.g methanoic acid, to have dispersion forces that outrank dipole-dipole forces?
Nikola Markoski's user avatar
2 votes
0 answers
117 views

Is Tkatchenko's MBD-NL method self-consistent?

I have a question regarding Tkatchenko's [1] new nonlocal many-body dispersion method (MBD-NL). Does anyone know if it's a self-consistent method? I read this paper many times but I'm still not sure. ...
Chruuz Roman's user avatar
0 votes
0 answers
61 views

Morse interatomic potential

I am working with Morse interatomic potential, I searched through the Internet but I could not find any Morse parameters for Zirconium element. Is there any table, handbook or something like these ...
user avatar
4 votes
1 answer
611 views

Hessian Matrix and Physical directions: Potential Energy Surface

How do the eigenvectors of the Hessian Matrix for potential energy surface correspond directly to the physical directions of translation, rotation and vibration? I see that they might correspond to ...
Mahathi Vempati's user avatar
8 votes
1 answer
1k views

How to obtain curve energy and non-bonded interaction parameters (e.g. Lennard Jones parameters) with Gaussian?

I am parameterizing a force field and would need to obtain non-bonded interaction parameters of atoms (e.g., Lennard-Jones parameters). My primary idea is to obtain a potential energy curve using the ...
Emerson P L's user avatar
5 votes
1 answer
99 views

When non-polar particles interact through dispersion forces, how fast does a temporary dipole induce a dipole in the neighboring molecule?

The current question is inspired by this existing question: At what frequency does a non-polar molecule acquire a dipole able to participate in London Dispersion forces?. In the comments and answers, ...
Karsten's user avatar
  • 42.3k
0 votes
1 answer
2k views

Which has a lower boiling point, Ozone or CO2? Why?

Ozone is a bent molecule, and therefore, Ozone is a polar molecule. Polar molecules have dipole-dipole intermolecular forces. CO2 is a linear molecule, and therefore, CO2 is a nonpolar molecule. ...
Ram Bhagat's user avatar
1 vote
0 answers
49 views

Distance Dependence of Weak Forces [closed]

I am currently taking a Biochemistry course and one of the topics on midterm covers various weak forces and its distance dependence. We covered: charge-charge (ionic) hydrogen bonds van der waals ...
user88315's user avatar
0 votes
1 answer
4k views

Why is the pressure correction added in the Van der Waals equation?

Since real gas particles experience attraction to each other, that means the pressure must be less from what we would expect. So why do we have to add a term to correct it? For example, in the ...
Micelle's user avatar
  • 191
6 votes
2 answers
127 views

What repulsion keeps non-hydrogen atoms at a distance: between inner shells or between nuclei?

Bonded or not, when two atoms or ions come closer than the bond distance or the van der Waals distance, the energy increases drastically. What is the underlying cause of that repulsion? The repulsion ...
Karsten's user avatar
  • 42.3k
2 votes
0 answers
67 views

Why don’t compounds with high boiling points not necessarily have high attraction constants (a) in the Van der Waals equation?

You can find a list of constants $a$ and $b$ for the van der Waals equation in a Wikipedia website. Accordingly, hexane has a higher attraction constant ($a$) than that for water (24.71 vs 5.536), but ...
Ryan's user avatar
  • 135
11 votes
5 answers
4k views

Pressure vs volume plot for real gas and ideal gas

Background Recently I have been studying about the states of matter and came to the topic of ideal gases and real gases, and the laws related to them. While studying it from my textbook, I saw the ...
user avatar
12 votes
3 answers
1k views

Why aren't the Anton computers used more widely?

The Anton computers are purpose-built by DE Shaw research for molecular dynamics simulations. They achieve performance up to an order of magnitude faster than can be achieved with commodity hardware, ...
mszep's user avatar
  • 438
7 votes
2 answers
849 views

How are London Dispersion Forces generated?

While talking about the gaseous state of matter we came to the topic of London Dispersion Forces caused by the generation of a dipole in one atom which induces a dipole in another. While talking about ...
user avatar
-4 votes
1 answer
2k views

Can a gas have a boiling point?

For each of the following pairs, choose the member with the lower boiling point. Explain your reason in each case. HI(g) or HCl(g) If they were both aqueous solutions, I would know that HCl has a ...
a23's user avatar
  • 23
0 votes
1 answer
196 views

Van der Waals forces [duplicate]

What exactly are Van der Waals forces? How do they arise and how can an instantaneous dipole cause another dipole? Shouldn't this make a chain reaction that causes all matter to eventually become ...
Micelle's user avatar
  • 191
0 votes
0 answers
99 views

Stability of alkenes

The following question was asked on myPAT website: I started with the solution by counting the hyper-conjugative structures available to each alkene. Based on this concept only, order is: I > ...
Rahul Verma's user avatar
  • 3,081
1 vote
1 answer
6k views

DNA pairs (adenine-thymine, guanine-cytosine) [closed]

Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine. From those pictures: Thymine has the lowest acidity and adenine has the biggest acidity. So it is logical that ...
user avatar
1 vote
0 answers
630 views

Why does chlorine gas have a higher boiling point than hydrogen iodide

Hydrogen iodide, $\ce{HI}$, is a dipolar molecule much larger than chlorine, $\ce{Cl2}$. The melting point of $\ce{HI}$ $(222.35\ \mathrm K)$ is definitely higher than that of $\ce{Cl2}$ $(171.6\ \...
chemN00b's user avatar
  • 342
8 votes
0 answers
272 views

Does water really have strong EM absorption at 3 kHz in solid and 2 GHz in liquid? Why the huge shift?

While writing this answer to the question Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement I ran across this large PDF file of a book Soil and Environmental ...
uhoh's user avatar
  • 5,997
0 votes
1 answer
259 views

Why does roasting requires lower temperature than melting point

Why do processes like roasting and calcination require a temperature lower than the melting point? Since intermolecular forces are lower in a liquid won't it be easier to oxidise (roasting) / ...
Tanisha Gupta's user avatar
1 vote
1 answer
982 views

Freezing point vs Intermolecular forces

Water has a higher boiling point (100°C) than cyclohexane (81°C). This is probably because of stronger intermolecular forces between water molecules as compared to cyclohexane molecules. Then, why is ...
UnoWindJTS's user avatar
-1 votes
1 answer
2k views

How can we find out the type of bonding present in a compound or a molecule?

For example, if the bonding in diamond, ice, MgO or CO2 is to determine, how can I find it out? How to determine van der Waals forces?
Noor Fishan's user avatar
0 votes
1 answer
72 views

As you heat up a substance will it's bonds begin to dissipate?

As you heat something up does it slowly start to dissipate? Water, for instance, boils at 100 degrees Celsius, but if you are heating it up at 90 degrees will its bonds be weaker?
firepanda225's user avatar
0 votes
1 answer
529 views

dipole–dipole interactions: OCR Sample Paper wrong? [closed]

I was doing OCR A Level Chemistry A, H432/01 Periodic table, elements and physical Sample Question Paper. Question 6 was: The boiling point of hydrogen bromide is –67 ºC. The boiling point of ...
EndUzr's user avatar
  • 117
0 votes
0 answers
704 views

Which has a high melting point, cocoa powder or cocoa butter?

I have been doing some research into chocolate, and after looking at the chemical compositions of cocoa butter and cocoa powder, struggled to determine which had a formula/structure that would have a ...
Matthew Cherry's user avatar
8 votes
1 answer
5k views

Why are the dispersion forces in CS2 stronger than the dipole-dipole forces in COS?

London dispersion forces supposedly have the least strength out of all the intermolecular forces. But $\ce{CS2}$, which has only dispersion forces, has a higher boiling point (and thus stronger ...
kat's user avatar
  • 203
0 votes
0 answers
977 views

Why does CH2F2 have such a low melting point?

The molecule is highly polar but the melting points are way lower than non polar compounds such CCl4 or other similar non polar compound. Do even dipole dipole have an affect on boiling point or is ...
Hucyxuc's user avatar
1 vote
0 answers
205 views

Condensation point of molecule compounds?

Which of the following gasses will condense at the lowest pressure (Assuming temperature is held constant)? $\ce{CBr4}$ $\ce{CH2Br2}$ I believe that compound 2 will condense at the lower pressure ...
Jane's user avatar
  • 19
1 vote
1 answer
701 views

Why does bromine increase the viscosity of olive oil? [closed]

Does bromine bond to the carbon in unsaturated fatty acids and break the double bonds between oxygen and carbon? Does this increase the viscosity of olive oil? Could someone give an elaborated ...
Almin Mekić's user avatar
0 votes
0 answers
39 views

Why does energy need to be "compensated" in order for solvation to occur?

I am currently learning about the physical properties of alcohols. I understand that the main intermolecular forces between alcohols and water are hydrogen bonds. When these two are mixed, the ...
Christopher U's user avatar
4 votes
1 answer
694 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 ...
Liam's user avatar
  • 640
6 votes
2 answers
1k views

Why is the Van der Waals constant of water lesser than benzene?

Van Der Waals constant of water and benzene ($a$) are $5.537$ and $18.82$ respectively. I have read that the value of Van Der Waals constant indicates the extent of attractive forces. By this, ...
Ceoxnojx's user avatar
2 votes
1 answer
2k views

Boiling point of ethanamide vs propanamide

I just have a question regarding the boiling points of some primary amides. Ethanamide has a boiling point of 222 °C, while propanamide has a lower boiling point of 213 °C. Both amides are capable of ...
PoH's user avatar
  • 467
15 votes
3 answers
4k views

Why does the exchange interaction in Hartree-Fock theory lower the total energy?

In Hartree-Fock theory, the expectation value of the total energy can be written as $$E = \langle\Psi| H |\Psi\rangle = \sum_{a} \langle a| h |a \rangle + \frac{1}{2}\sum_{ab} \big( [aa |bb] - [ab|ba]...
Hayden S's user avatar
  • 736
3 votes
1 answer
7k views

What effect on boiling and melting points does intramolecular hydrogen bonding have? [duplicate]

I know that intermolecular forces increase the boiling and melting point of a compound, but what is the effect of intramolecular forces on boiling and melting points? I found contradicting answers ...
Ishan Jawale's user avatar
1 vote
0 answers
84 views

Is the 12-6 Lennard Jones potential a good description of van der Waals interaction energy?

It seems to me that the Lennard Jones potential oversimplifies the more complex nature of van der Waals forces. However, in most of the MD simulation package, this is generally accepted.
Rheologist Ph.D.'s user avatar
11 votes
1 answer
1k views

Can a long polymer chain interact with itself via van der Waals forces?

It is known that van der Waals interaction is an intermolecular forces. So is it possible that a long polymer chain interacting with itself via non-bonded interactions (such as van der Waals forces / ...
Rheologist Ph.D.'s user avatar
1 vote
1 answer
50 views

What is a good resource for learning about the intermolecular bonding in water beyond high school? [closed]

I'm writing a paper for school on boiling water at various temperatures and pressures, but only noting cases wherein high temperatures were achieved without boiling under low pressure (metastable ...
John Miller's user avatar
2 votes
1 answer
2k views

Radial pair distribution function (VMD). How to define it for a water NaCl system with multiple Na and Cl?

I'm struggling to understand a paper in which someone has presented radial distribution functions (RDFs) for a system that contains multiple Na, Cl, and water atoms/molecules. I don't know exactly ...
user3292696's user avatar
0 votes
2 answers
28k views

How can I determine the highest boiling point given a list of molecules? [closed]

I know that the highest boiling point has to do with which has the strongest intermolecular force. I also know that the strongest would be ionic, then hydrogen bonding, then dipole-dipole, then london ...
user130306's user avatar
2 votes
1 answer
4k views

Ionic compounds and van der Waals forces

I'm having trouble understanding exactly what intermolecular forces occur in ionic compounds. What I understand is that ionic compounds are held together by electrostatic interactions between ...
chchchchemistry's user avatar
1 vote
1 answer
613 views

Complementary base pairing

In the molecular structure of a DNA it is seen that purines (adenine and guanine) bind with pyrimidines (cytosine, uracil and thymine) through hydrogen bonds, and this is always between a purine and a ...
chinmai's user avatar
  • 111
16 votes
2 answers
13k views

Why does graphite have a high melting point even though its intermolecular forces are weak?

From what I've read online, when a substance undergoes a state change, the intermolecular forces are broken. The covalent bonds are not broken (http://www.bbc.co.uk/schools/gcsebitesize/science/...
Christopher U's user avatar
8 votes
3 answers
4k views

What is the maximum distance over which van der Waals forces act?

The VDW radius places a lower limit on the distance between atoms mutually attracted to one another. I am looking for the upper limit: what is the name of the concept or theory that describes the ...
charlie_sar's user avatar
5 votes
3 answers
2k views

Does gas chromatography follow the "like interacts with like" rule of thumb?

The "like interacts with like" rule of thumb works well when there are polar and non-polar molecules that are mobile (liquid-liquid extraction, membrane vs cytosol, questions of solubility). Polar ...
Karsten's user avatar
  • 42.3k
0 votes
2 answers
514 views

What would be the intermolecular forces between the molecules of methanetetrol?

Methanetetrol has the following chemical formula: $\ce{CO4H4}$. It is also referred to as orthocarbonic acid. Since the molecule has a molecular geometry of a tetrahedron, similar to that of a ...
Lisa Hansen's user avatar
-1 votes
1 answer
840 views

Why is boron or carbon solids and chlorine a gas at room temperature

I know different compounds have different states at room temperature because of inter-molecular forces ( dipole-dipole force, hydrogen bonding, and London dispersion forces). But how do they act on ...
Poin's user avatar
  • 129

1 2
3
4 5
8