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.
396 questions
1
vote
2
answers
1k
views
Do molecules with polar bond, but with no dipole moment experiences a greater effect from the london dispersion forces?
Do molecules that have polar bonds and a structure that makes the polarity of those bonds cancel each other out, experience a greater effect from the London dispersion force, than molecules with a ...
- 55
1
vote
0
answers
48
views
Non-covalent interactions
According to Keesom, Debye and London effect, the non-covalent reactions should be stronger, the bigger are electric charge differences between two interacting particles. E.g. Ion-induced dipole are ...
- 95
2
votes
0
answers
276
views
What type of interactions occur when CH4 dissolves in CCl4 [duplicate]
When ionic compounds dissolve in polar solvents many types of factors come into play determining their solubility. Some of them may be: ion- dipole interactions, lattice energy, high dielectric ...
- 197
2
votes
0
answers
7k
views
Why do stronger intermolecular forces lead to a larger change in temperature?
We performed an experiment where tissue paper soaked in various chemicals was wrapped around the end of a temperature probe.
The chemicals with stronger intermolecular forces had a smaller drop in ...
- 109
1
vote
3
answers
502
views
Why does atomic charge not balance in nuclear reactions?
In the discovery of neutron, the bombardment of beryllium with alpha particles is well known.
$$\ce{^9_4Be + ^4_2He^2+ -> ^12_6C + ^1_0n}$$
I don't understand how the electrons add up. As alpha ...
- 31
2
votes
1
answer
110
views
Understanding water models?
I generally work on fluid flow, so some basic concepts in chemistry are new to me.
Work I'm doing requires use of molecular dynamics (MD) to do classical potential simulations of water–NaCl systems ...
- 29
0
votes
0
answers
61
views
How can I define a torsion force field for $n$ points in space?
I would like to define a model for torsion force field between $n$ point in space.
I thought to generalize the OPLS model:
$$
\sum_\mathrm{dihedrals} \left( \frac {V_1} {2} \left [ 1 + \cos (\phi-\...
- 924
2
votes
1
answer
434
views
Calculate force on atoms given the energy of configuration, trajectory of simulation and position of atoms in each frame
Background
I am using a neural network to calculate the potential energy of atoms in a configuration and then adding energy of all atoms to compare it with the true energy of the configuration(label) ...
- 460
2
votes
3
answers
972
views
If all intermolecular forces are electrostatic in nature, why don’t large non polar molecule dissolve in water?
If I have a large non-polar substance A that forms strong dipole-induced dipole force (DIDF) with water, with strength comparable to that of H-bonds between water molecules, will A dissolve in water?
- 37
0
votes
1
answer
209
views
Relative magnitudes of intermolecular forces from phase diagrams
Is it possible to say whether or not a system A or B has stronger intermolecular forces from a phase diagram according to which:
The $T_{\text{b}}$ of A is lower than the $T_{\text{b}}$ of B.
The $T_{...
- 11
1
vote
1
answer
956
views
Intermolecular interaction between aniline and dichloromethane
Short background
As it is known there are interactions between:
Charges
Charge and dipole
Hydrogen bonding
van der Waals (VDW) forces
From stronger (1) to weaker (4).
VDW forces are divided into ...
user43021
2
votes
1
answer
127
views
Relating properties and structures of polymers
Why would it be more favorable for a polymer designer to design copolymers with irregular chain structures, rather than design homopolymers?
Hint: Discuss intermolecular bonds
I understand that ...
- 83
0
votes
1
answer
174
views
What are the intermolecular forces between polychloroethylene?
Does polychloroethylene have only van der Waals/London forces between its molecules? Surely, if all the chlorine atoms are on one side, due to the fact that chlorine is more electronegative than ...
- 11
-1
votes
1
answer
185
views
Help with Carbon Fibre
I'm having trouble finding articles about carbon fibre that don't contradict other articles. I just have a few questions about the atomic structure and the intermolecular and intramolecular forces.
...
2
votes
1
answer
313
views
Is the electrical conductivity only measurable in aqueous solutions? [closed]
I have been looking for other ways to measure it, but all I've found is through aqueous solutions. So I want to know if there's another way to do it, or why it isn't possible through other means.
1
vote
0
answers
32
views
Why don't all atoms stick together due to dispersion forces if these forces are ubiquitous? [duplicate]
If dispersion forces are always there wherever there are electrons, why don't two pieces of copper for instance meld together when put next to each other? Or why don't other substances stick to each ...
- 803
0
votes
1
answer
5k
views
Why does Xe have a higher boiling point than Ne? [duplicate]
I am certain that the reason involves intermolecular forces, but since both $Xe$ and $Ne$ are noble and non-polar gases, shouldn't these forces have a much smaller effect or negligible on boiling ...
- 111
1
vote
0
answers
250
views
Why do intramolecular forces weaken due to heat?
In my most recent research into thermoplastics, I was unable to find any information regarding what actually happens to intramolecular forces when heat is applied.
0
votes
0
answers
195
views
Experimental bond lengths and binding energies of diatomic molecules
Is it possible to find the experimental values of the bond length and the binding energy of the diatomic molecules $\text H_2$, $\text{Be}_2$, and $\text{Ar}_2$ in one source?
I found a lot of ...
- 319
0
votes
1
answer
3k
views
Will ice be cold or not when formed using pressure? [closed]
We know that ice can be formed either by lowering the temperature of water or by applying more pressure. If we lower the temperature of water the ice so formed will be cool which is obvious.
If ice ...
- 11
-1
votes
2
answers
2k
views
What makes a diatomic bond strong? [closed]
What are the factors affecting the strength of bonds?
Ex:- why, we need less amount of energy to break Br-Br bond than Cl-Cl bond?
- 11
-1
votes
1
answer
403
views
electronegativity and hydrogen bonding [duplicate]
I have a basic idea why, but can someone just confirm, why chlorine isn't able to hydrogen bond despite the fact that it has the same electronegativity value as nitrogen.
- 685
1
vote
0
answers
19
views
How to know if a sample suffered descomposition during melting point? [closed]
If I take a sample in order to determine its melting point, how do I know if that sample suffered a descomposition?
- 49
0
votes
0
answers
56
views
What is "time-dependent evolution of the complex noncovalent interaction networks" and why this is important?
From Maximilian Scheurer, Peter Rodenkirch, Marc Siggel, Rafael C. Bernardi, Klaus Schulten, Emad Tajkhorshid and Till Rudack Biophysical Journal, Volume 114, Issue 3, 577-583:
One of the most ...
- 924
-2
votes
1
answer
577
views
London Dispersion Forces and Dipole-Dipole forces together? [closed]
How do London Dispersion Forces and Dipole-Dipole forces exist at the same time between polar molecules?
- 21
0
votes
1
answer
292
views
Van der Waals interaction and magnetic dipole dipole interaction
I have a conceptual question that bothers me.
From what I understand, van der Waals forces are the primary source of inter-molecular interaction. There are three different possible origins for van ...
- 69
24
votes
2
answers
11k
views
Why do alkanes have higher boiling point than their ether counterparts?
Based on my understanding of intermolecular forces, I expect dipole-dipole interactions to be significantly stronger than van der Waals' interactions. Hence, I expect ethers (which obviously have ...
- 373
1
vote
1
answer
382
views
Surprising values of intermolecular forces of ethane, oxygen and xenon
I know that gases with stronger intermolecular forces should have a larger value of the van der Waals constant $a$. So I looked up a table on van der Waals constants and tried to reason about the ...
- 373
3
votes
0
answers
91
views
Why is this scintillator component turning into a milky-white emulsion?
I am a chemistry and physics double major doing some chemistry work in a nuclear physics lab. My mentor is a physicist, so his area of expertise is occasionally mismatched with what I need for my ...
- 131
1
vote
1
answer
556
views
Are intermolecular forces a type of chemical bond?
My chemistry teacher told me that chemical bonds are of two types: intramolecular and intermolecular. He said that intermolecular forces come under the category of intermolecular chemical bond.
I ...
- 509
1
vote
1
answer
5k
views
Why does acetone have a lower boiling point than hexane?
Why does acetone have a lower boiling point than hexane? I thought that since hexane is non-polar then it should have weaker intermolecular forces and a lower boiling point, but it doesn't. Why?
For ...
- 19
16
votes
1
answer
2k
views
How are polarizabilities measured experimentally?
Most common spectroscopies that produce either a full spectrum, a tensor, or a scalar value have a specific instrument associated with them that is relatively self-contained and not custom. For ...
- 7,530
5
votes
1
answer
5k
views
Why is the boiling point of polonium less than that of tellurium?
My textbook states that polonium has a lower boiling point than tellurium because it has weaker intermolecular forces of attractions (van der Waals forces).
Why are van der Waals forces of attraction ...
- 2,239
14
votes
2
answers
2k
views
How to identify hydrogen bonds and other non-covalent interactions from structure considerations?
Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically ...
- 44.4k
5
votes
1
answer
2k
views
For two compounds that are symmetrical, why does the more compact one have a higher melting point?
In this post, I refer to two molecules B (Di-tert-butyl ether) and C (Dibutyl ether).
Wikipedia: Di-tert-butyl ether (B)
b.p. 107.2 C
m.p. - 61 C
...
- 155
1
vote
1
answer
4k
views
Why is the boiling point of hydrogen sulfide higher than that of hydrogen chloride?
The boiling point of $\ce{H_2S}$ is higher than $\ce{HCl}$. Is this due to the greater number of hydrogen bond that $\ce{H_2S}$ can form compared to $\ce{HCl}$? I found this explanation for the ...
- 225
1
vote
2
answers
3k
views
If we start heating a substance, does it melt when we break its intermolecular bonds? [closed]
I was reading the 2 following posts:
Do substances melt when we break their intermolecular bonds?
Is melting/boiling point of ionically bonded substance higher than of covalently bound?
Altough ...
1
vote
0
answers
24
views
Chemical bonding [duplicate]
How do we compare the strength of permanent dipole permanent dipole (PDPD) interaction? Is it by bond polarity?
Since H-X (where X is halogen) is polar, and for bond polarity (PDPD bond strength): ...
- 19
17
votes
1
answer
7k
views
Why is the melting point of PCl3 less than that of PCl5?
From just the IB chemistry bonding chapter information, you would normally deduce that $\ce{PCl3}$ and $\ce{PCl5}$ are both covalent molecules.
However, as $\ce{PCl3}$ has a dipole moment, it has ...
- 299
5
votes
1
answer
602
views
Reversed size dependence in ion solubility
My book says that solubility increases with interionic distance, because the attractive forces between ions gets smaller. However, if one of the ions in a binary ionic system is very large compared to ...
- 435
1
vote
2
answers
6k
views
Forces of attraction of hydrated potassium ion in aqueous solution
I want to study the intermolecular forces (IMFs) in hydrated potassium ion, $\ce{K+ (aq)}$ in an aqueous solution of $\ce{KCl}$. According to my thoughts, among the 4 IMFs I know:
London dispersion ...
- 409
6
votes
0
answers
795
views
How can copper(II) sulfate crystallize outside a glass vial?
I'm making copper sulfate crystals in glasses. Within a few weeks, the copper sulfate seems to crystallize both inside and outside the glass:
(A few weeks after making a new solution)
(Yet another ...
- 191
7
votes
1
answer
7k
views
Why do chloroform and benzene exhibit negative deviation from Raoult's law?
Chloroform is a polar molecule, and benzene is nonpolar. Shouldn't the chloroform-chloroform and benzene-benzene intermolecular forces be stronger than chloroform-benzene interactions (like dissolves ...
user28295
-1
votes
2
answers
24k
views
How do you tell which molecule has a higher melting point?
In the instance of comparing $\ce{NaCl}$, and $\ce{Al2O3}$; which one has a higher melting point and why?
I have learned the following inter molecular forces, however the question the chapter is in ...
- 153
13
votes
1
answer
405
views
Possibility of π–π stacking in non-aromatic systems
Is it possible to have π–π stacking for non-conjugated double bond systems?
For example, can the carbonyl groups of two urea molecules participate in π–π stacking? Although urea prefers to stay in ...
- 981
5
votes
3
answers
4k
views
Reasons for solid or liquid soap
Soap is made by a saponification reaction, where a fat reacts with hydroxide ions to form a surfactant and glycerol.
To make a solid soap $\ce{NaOH}$ is used, while $\ce{KOH}$ is used for liquid ...
- 1,277
2
votes
0
answers
53
views
Calculate activation energy of intermolecular displacement on a nano particle
I'm simulating a nano particle and wish to calculate the activation energy of the reaction where an atom is displaced from one point on the lattice to a neighboring void( might be at higher energy ...
- 460
-2
votes
2
answers
1k
views
Ordering compounds by boiling points
Here is a MC question from my chemistry professor:
What is the correct order of boiling points for molecules: $\ce{CO2}$, $\ce{LiOH}$, $\ce{CH3OH}$, $\ce{CH2O}$?
I am mainly confused about ...
1
vote
0
answers
29
views
Why do elements transition discretely between solid, liquid and gas forms, rather than existing as a spectrum? [duplicate]
I don't understand what makes a liquid entirely different from a gas, why wouldn't a liquid slowly become more gaseous, but instead transition completely from one form to the other?
- 11
10
votes
1
answer
8k
views
Why do higher-mass isotopes have higher melting and boiling points than lower-mass isotopes?
Different isotopes of the same element have the same number of electrons, so the nature of bonding between different isotopes of the same element should be the same, yet their melting points and ...
- 121