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11 views

Forces from molecular potential energy surface

Let's assume we cannot use Hellmann-Feyman theorem and we wish to calculate the forces on molecules' atoms at arbitrary configuration only from its potential energy. My question is how many different ...
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1answer
55 views

Are lighter molecules in the air more affected by earth gravity?

Or: Why are raindrops falling? In vacuum a heavy (big mass) object is attracted by gravity with the same speed as a light object as shown on the moon with the hamer and the feather. But on earth ...
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0answers
27 views

Carbon dioxide oscillations along main axis ---TRICKY PROBLEM— [closed]

I'm completely new to physics.stackexchange.com. I would like to try this kind of service. I have received a problem from my professor which sounds like this : "Carbon dioxide molecule in ...
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2answers
121 views

If a water molecule is neutral how do water molecules attract one another by electric force & form water?

This no sense to me! (im new to physics) and my textbook didnt explain this well!
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2answers
38 views

Motion of molecules of an ideal gas

Why does an ideal gas show only translatory motion and not vibratory motion?
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0answers
49 views

What is the max frequency of sound in a given medium?

When talking about acoustic waves, medium continuity (pressure, density) is implicit. But can the wavelength of an acoustic wave be as small as intermolecular separation? For example, can ~10 THz ...
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1answer
15 views

Methods to ioniz air molecules

What are other alternatives ways to ionize air molecules, except the electric field charging and the use of the so-called corona discharge?
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2answers
50 views

Creasing of a material at the molecular level

What exactly happens when a material (particularly paper or even cloth or a metal) is folded to form a crease? Why is it that a creased material tends to retain form, while a lightly folded one, '...
2
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0answers
39 views

Plasmon quenching vs plasmon decay. What is the difference?

I'm reading an article "Quenching, Plasmonic, and Radiative Decays in Nanogap Emitting Devices" (pubs.acs.org/journal/apchd5). I don't understand the following: Counterintuitively, we evidence ...
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0answers
16 views

Average Rate of Evaporation of Water

Consider a container of volume $V$ and cross sectional area (exposed to another fluid, say air) $SA$. The container is at constant temperature $T$, and contains $N$ molecules of water, where $N$ is ...
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2answers
59 views

Do homonuclear diatomic molecules interact with infrared light?

A molecule will appear on IR spectra if its dipole moment changes during vibration. Due to symmetry, the dipole moment of homonuclear diatomic molecules ($\mathrm{H_2, N_2, O_2, F_2, \dots}$) is zero. ...
3
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0answers
38 views

If 2 fermionic atoms form a molecule, will the molecule always behave as a boson?

2 fermionic atoms give a bosonic molecule. 2 bosonic atoms form a bosonic molecule. Is there a energy scale where these two molecules will behave differently? If yes, will it depend on the ...
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1answer
57 views

Any Antimolecule so far?

As i've been reading on Wikipedia, we are artificially able to join an antiproton with a positron to form an antihydrogen. But if i search for antimolecule, i can't find any results on that, only a ...
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1answer
73 views

Can two different objects or system of molecules have different temperatures, but having same internal kinetic energy?

If I take an extreme case, where a body has only an internal potential energy with zero internal kinetic energy, does this body have a temperature? Another question related to it: if two objects A and ...
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1answer
32 views

Neutron scattering off molecules

From neutron scattering off molecules it is possible to get information about molecules' geometry. Given the size of a particular molecule, what are the criteria for choosing the wavelengh of the ...
0
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1answer
51 views

Atomic number of $\rm CO_2$? [closed]

I have to calculate the Bethe-Bloch equation for a $\rm CO_2$ absorber, I know this is a stupid question, but is Atomic number additive? Or do I need to do something a little more complex? I was ...
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0answers
28 views

Why do very small balls attached to a tiny spring propel themselves in hardly moving fluids? [duplicate]

I recall watching a youtube video about a ball with a spring on the idea propelling themselves through stable fluids without any assistance, even if we make sure the spring isn't moving in the ...
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0answers
100 views

How do proteins perform their function? [closed]

Let's, for example, take a ribosome. It is an enzyme that is in turn just a molecule that must follow the laws of physics. Correct me if I'm wrong, but it can be looked upon as a molecular machine ...
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1answer
31 views

Does less heat equals more reflexion? [duplicate]

Does colder metal reflect more if hotter metal reflect less? Why?
0
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1answer
46 views

can odorous VOCs be removed by an ionizing air purifier? [closed]

I am considering replacing my IQAir HealthPro 250 air purifier by an Electrolux EAP300. According to the marketers, the EAP300 has PlasmaWave(TM) technology that supposedly removes odours from the air ...
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0answers
35 views

how can VOC filters work given that atmosphere has 1800 ppb methane?

I have an IQAir HealthPro 250 air purifier that has a 2.5 kg activated charcoal volatile organic compound (VOC) filter. According to the manufacturer, the replacement interval is from 12 to 24 months. ...
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3answers
186 views

Why is alcohol less dense than water?

Ethyl alcohol (ethanol) is less dense than water, and it's boiling point is lower. But this molecule is more complex and bigger than the simple H2O. How can a substance with a higher molecular size ...
2
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0answers
39 views

Why is CO a good tracer for H2? How are those molecules correlated?

One always reads and hears that CO is a good tracer for H2. How are they correlated? How can you deduce from the (measurable) CO the amount of the (unmeasurable) H2 in the ISM?
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2answers
129 views

Can $CO_2$ be separated into $C$ and $ O_2$?

I'm doing a little bit of research for an experiment that I want to conduct in science and it relies on that one question. So, Is it possible to separate a $CO_2$ molecule into a $C$ and $O_2$? ...
3
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1answer
65 views

How do molecules absorb heat?

How do molecules absorb and retain heat, and how is that heat able to still affect nearby molecules? On Venus there is a green-house effect where the large, dense Carbon-Dioxide atmosphere absorbs ...
0
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1answer
58 views

Atoms Inside a Lightning Bolt

What happens to atoms trapped in lightning? Why do electrons not split an atom but can change them inside the bolt? Can atoms travel on a bolt?
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2answers
111 views

Mountains and their local effects on Earth's gravity

I was once a truck driver and can feel the inertia and kinetic energy on heavy loads while traveling. While climbing mountains in the Rockies I noticed gravity was different on the side of the ...
0
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1answer
74 views

How to determine rotational energy of gas molecules

For an arbitrary polyatomic molecular gas, what is the expected behavior of $U_{rot}(T)$, the rotational kinetic energy of the atoms, in the two limits T high and T low? So far, I have written an ...
0
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1answer
52 views

How can I determine the vector parallel to the long molecular axis?

I have a molecule in a system (the molecule is not in the center) with determined coordinates of all atoms. One of my molecule is on the picture below What I need is to determine the vector that ...
2
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2answers
51 views

When dihydrogen is formed, are photons being emitted?

When a hydrogen in an excited state transits back to the ground state, a photon (or series of photons) is emitted in accordance with the selection rules. When two free hydrogen atoms in the ground ...
1
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1answer
70 views

Is (or why isn't) static charge as lethal as ionizing radiation?

Ionizing radiation, e.g. the "stuff" emitted by radioactive materials, is dangerous to humans since changes to the electron configurations (in the human body) causes the various molecules (in the ...
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3answers
66 views

Splitting molecule

The photon reacts with the binding electrons orbiting the two atoms. The photons have the 'correct' wavelength for Bond Dissociation Energy (BDE). 'Splitting' the molecule involves applying the ...
0
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2answers
605 views

How are bond angles determined?

Electron microscopes cannot clearly depict the exact shape and structure of atoms and molecules, even though it does show a vague, cloudy image. In my AP chemistry class, I learned that the bond angle ...
0
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1answer
79 views
2
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1answer
3k views

Degrees of freedom in a diatomic molecule [duplicate]

We know that a monatomic compound can only have 3 degrees of freedom as we can consider it to be a point mass. However now that we consider a diatomic molecule, there are 3 degrees of freedom in ...
1
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1answer
150 views

Do solids have translational energy?

Along with having vibrational energy, do both crystalline and amorphous solids also have translational energy? I ask because I've always understood solids to have just vibrational motion/energy. But ...
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0answers
12 views

Can the atomic vibration of molten liquids be decomposed into a superposition of a series of normal modes?

From what I've learned, molten liquids have short-range periodicity (short-range doesn't just apply to the amorphous solid state/glassy state). So does this mean that, along with amorphous solids, the ...
2
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1answer
117 views

Why titanium “writes” on glass , meanwhile don't scratching it?

It is possible to "write" on a piece of glass with a bar of titanium without scratching the glass. I think the explanation is that molecular connections in glass are stronger than in titanium and ...
2
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3answers
212 views

What happens to the $PV=nRT$ formula as the gas enters the liquid phase?

The formula $PV = nRT$ explains the relationship between pressure, volume and temperature in terms of the quantity of gas present in a container. I'm trying to understand how these are related once ...
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0answers
36 views

Can a buckyball gun be fired by observing it?

If a buckyball was placed inside a gun made from maybe a carbon nanotube or something, would measuring the momentum of the buckyball cause the the gun to fire? At what speed would the buckyball exit ...
3
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2answers
76 views

During the “Dark Ages” of the Universe's evolution, how lumpy (anisotropic) and dynamic was the mass distribution?

In the dark ages between recombination (~0.4 Myr post-BB) and reionization (~300 Myr post-BB) of atoms, there was not any condensed-phase matter (except maybe some form of dark matter), nor radiation ...
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0answers
60 views

Can a molecule be ionized by absorbing the energy of more than 1 photon?

I'm wondering if a molecule can absorb more then 1 photon before releasing a photon. The reason I'm asking is I would like to ionize a molecule with light but the frequency of light this molecule ...
0
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1answer
34 views

Shape of interface between molecules [closed]

Two seas do not mix, what are the characteristics of the interface? If we are trying to draw the molecules together, what would the interface look like?
1
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1answer
45 views

What is thermophoresis?

I read wikipedia article and I saw a bad youtube presentation on thermophoresis, however I don't have a clear insight about the subject. I assume the forces are basically Brownian molecular forces ...
0
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0answers
57 views

Difficulty in understanding Maxwell Boltzmann distribution in case on ions in a field

I learned that the velocity of molecules obey Maxwell Boltzmann (MB) distribution at a Temperature T. If I have ions of mass 'M' accelerated to 2eV in a specific region. As the ions are not "...
0
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0answers
9 views

debris removal by electrification

Often during the lifetime of equipment, there is debris or residue accumulation on surface of, for example nozzles. This material accumulation can be quite strong. What kind of forces are they ...
0
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1answer
42 views

Why toilet paper is softer in moist air? [duplicate]

After a hot shower,the air from the bathroom is full of water steam,right? How does the air affect the texture of the toilet paper?I mean,the toilet paper it seems to be softer,but why? Can someone ...
2
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1answer
2k views

Finding the approximate distance between molecules in a gas

I have a problem to understand why the below derivation can be used to find the distance between molecules: This example is an approximation. We are supposed to find the average distance between the ...
2
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0answers
89 views

Why is the activation energy of combustion so large compared with regular bonding?

I wanted to know why combustion requires an activation energy and I found this article (see this too). It says that molecular oxygen ground state is a triplet state (according to Hund's rules), and ...