Study of macroscopic and microscopic phenomena in chemical systems in terms of physical laws and concepts [thermodynamics, statistical mechanics, kinetic theory, quantum mechanics...].

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145 views

Which bonds are the cross-links and which are secondary bonds (in elastomers)? [closed]

Elastomeres are "defined" as: "linear-chain polymers with widely spaced cross-links attaching each molecule to its neighbours" Now I found sentences (talking about glass transition): "This means ...
5
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1answer
226 views

What equation describes the electrostatic potential in these circumstances?

I have a solver for Poisson's equation and it works nicely. It uses finite differences. It works in the presence of multiple dielectrics. It also solves the Poisson Boltzmann equation. That is, fixed ...
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1answer
3k views

Can I calculate the maximum concentration of sucrose that will dissolve in water at STP using physical constants?

I am interested in identifying the maximum solubility of sucrose in water. Can this value be estimated based on the physical properties of sucrose? Eventually I will need this in degrees Brix (%w/w). ...
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1answer
404 views

Addition of a neutral electrolyte to water— how can it increase conductivity?

Sparked off by Is sea water more conductive than pure water because "electrical current is transported by the ions in solution"? This question really belongs on chemistry.SE, which is ...
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1answer
989 views

How does a stronger magnet affect the MRI image quality?

In which ways is a stronger magnet better for magnetic resonance imaging? I read that: The field strength of the magnet will influence the quality of the MR image regarding chemical shift ...
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1answer
4k views

Why is oxygen in a triplet state and what are the consequences?

From Wikipedia here and here: ''Almost all molecules encountered in daily life exist in a singlet state, but molecular oxygen is an exception.'' ''The unusual electron configuration prevents ...
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1answer
519 views

How specifically do emulsifiers work?

I'd like to understand better how emulsifiers prevent droplet coalescence. There must be something more they do than just lower the surface tension between the droplet and the ambient substance. I ...
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2answers
1k views

What meaning do changes in the absolute value of Gibbs free energy have in a simple expansion process?

Below is a simple representation of the thermodynamics of a steam turbine. Stream kinetic and potential energy changes are neglected and no other type of non-PV work is done besides shaft work. ...
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2answers
317 views

When do thermal and chemical equilibrium not coincide?

What is an example for a system, which is in chemical equilibrium, but not in thermodynamical equilibrium? And what about the other way around? It seems to me, that as long as Parameters like ...
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1answer
713 views

What does activation energy actually do?

Spontaneous (exothermic) chemical reactions often require a push from the addition of externally supplied energy. This energy is often called activation energy. What does activation energy actually ...
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2answers
360 views

Statistical Mechanics treatment of the reaction process?

I'm searching for an at least semi-rigorous Statistical Mechanics description/treatment of a (spatially resolved) chemical reaction process of a macroscopic portion of at least two different species ...
4
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1answer
621 views

Energy per particle vs. chemical potential vs. evaporation energy

There is a system of N particles. They interact and are bound together with a binding energy Eb (or potential energy). To characterize the system there are multiple terms Energy per particle Eb(N)/N ...
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2answers
1k views

How thin a filter to filter particles out of salt water to make salt for human consumption?

I have gathered some salt in the Death Valley and for the fun of it I would like to clean it and make it edible. The process I plan to follow is simple: Dissolve the salt in water. Boil water for ...
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1answer
174 views

THT (Tetrahydrothiophene) absorption spectrum

I am looking for the absorption spectrum of THT. What is the best way to find these types of exotic material's spectral characteristics?
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3answers
11k views

Why does the water rise?

It's a very popular experiment (eg), from elementary school : put a burning candle on a dish filled with water, cover the candle with an inverted glass: after a little while, the candle flame goes ...
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3answers
591 views

Nanorobots. What stops us from producing them yet?

If we can already predicts accuratelly motion on molecular levels, what stops us from developing small robots to, for instance, navigate through our blood vessels looking for cancerous cells and ...
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1answer
103 views

Why don't the actinides start at neptunium?

In their physical and chemical properties, actinium, thorium, protactinium, and uranium are respectively similar to lanthanum, hafnium, tantalum, and tungsten, and thus would seem to belong ...
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2answers
1k views

Is the Mendeleev table explained in quantum mechanics?

Does anybody know if there exists a mathematical explanation of Mendeleev table in quantum mechanics? In some textbooks (for example in F.A.Berezin, M.A.Shubin. The Schrödinger Equation) the authors ...
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3answers
663 views

Is mass-energy conversion in chemical reactions experimentally observable

This is a common point of argument on internet forums. I think it is fairly well established theoretically that there is a very small amount of mass converted to energy in an exothermic chemical ...
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1answer
291 views

The 2011 Nobel Prize in Chemistry

As far as I understand a new pattern of crystal growth has been found experimentally. How does it relate to the known 2D and 3D nucleation and growth of crystals? The dominating theory of crystal ...
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0answers
92 views

Calculating the required amount of acid/base to reach a pH [closed]

Bit stuck on working this out - or if it is even possible. I have a reservoir of solution (water/plant feed/dead flies) that is pH 6 and I want to get it to pH 6.25. Here is the information I have: ...
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3answers
4k views

Why is the energy density of gasoline so high?

We sometimes play a game in my family whereby we trace the energy for a device back to it's source: The Xbox got power from the wall. The wall got power from the local transformer. The transformer ...
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6answers
8k views

How was Avogadro's number first determined?

I read on Wikipedia how the numerical value of Avogadro's number can be found by doing an experiment, provided you have the numerical value of Faraday's constant; but it seems to me that Faraday's ...
4
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1answer
245 views

Voltage drop over a cell membrane

Again, a problem from exam preparation: [A] cell's membrane allows sodium ions to pass through it, but not chlorine ions. The cell is placed in a salty solution with a ten times higher ...
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1answer
183 views

Circulate smoke in a closed system

Hey i am by no means a scientist but i have a idea for a art work using smoke. Basically what i want to know is whether it is possible to circulate smoke by means of a pump through a transparent box. ...
2
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1answer
196 views

Is it possible to mechanically isomerize an sp3 hybridized carbon center?

Imagine I have an sp3 hybridized carbon attached to four separate polyethylene chains. By pulling on the polyethylene chains in some manner, is it possible for me to mechanically isomerize the chiral ...
3
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1answer
473 views

Why is E85 less efficient than straight gasoline?

Why is straight gasoline (or whetever the mixture was before the introduction of ethanol) more efficient (ie, more miles/gallon) than E85? I've known since it's introduction that E85 was less ...
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1answer
5k views

List of immiscible liquids

I'm looking for a list of immiscible (and miscible) liquids. I currently developing a game that will use the property of differents liquid, some of them will mix, other will not (positioning in the ...
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3answers
498 views

The “binding energy” of bonded particles adds mass?

This is a follow-up my previous question. Several of the answers indicated that the mass of a particle (atom, proton, etc.) increase with the "binding energy" of it's component particles - the energy ...
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5answers
5k views

Conversion of mass to energy in chemical/nuclear reactions

Is mass converted into energy in exothermic chemical / nuclear reactions? My (A Level) knowledge of chemistry suggests that this isn't the case. In a simple burning reaction, e.g. $C+O_2\to ...
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1answer
247 views

Physical Chemistry: What's the relationship between orbital overlap and barrier shape?

This is a question for the physical chemists out there. For a given chemical reaction there is a barrier to traverse in order to proceed from reactants to products. Reactants e.g. an organic base ...
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3answers
2k views

Air Regeneration in Closed Systems

I wonder what's the way to regenerate O2 in air without using consumable chemicals (where one can use electricity through electrolisis or using UV lamps)? We can dissolve water into O2 & H2, but ...
3
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3answers
439 views

How would steel degrade in space

If there is a steel plate floating in space, for ever, within the solar system, how is it going to degrade? Of course without oxygen it is not going to oxidize (rust), but how are cosmic rays, UV ...
2
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1answer
242 views

Vapor pressure higher than equilibrium vapor pressure

Is there any mechanism by which the vapor pressure of a liquid substance (lets say in a vacuum) is measured to be greater than the expected saturated vapor pressure at that temperature? Specifically, ...
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7answers
7k views

Explanation of “thermite vs ice” explosion

There are several videos of the reaction, where some amount of burning thermite explodes on a contact with ice. An "original" video: http://www.youtube.com/watch?v=IuPjlYxUWc8 A Mythbusters ...
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1answer
216 views

Are valence electrons located solely in the s and p subshells?

Or are they in all subshells??
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2answers
913 views

What happens to chemical compunds that include radioactive nuclei, when those decay?

Say you have a chemical compound made up of one or more radioactive nuclei. If the nucleus decays, does the compound? Possible outcomes I can think of: the compounds continues to exist if a ...
3
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1answer
1k views

Chemical potential interpretation

Something that has bothered me for a while regards the interpretation of chemical potential for different statistics. While I understand its meaning in metals (and its relation with the Fermi ...
3
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1answer
243 views

determination of voltaic cell voltage

if i understood this correctly, the determination of voltage for a specific voltaic (gallvanic) cell is determined only by the chemical correlation between the two metals. is this true? for an ...
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1answer
399 views

What is the purpose of a “protect from light” warning?

Some food or medical items, like rasberry juice concentrate I just bought, have a "protect from light" warning on the label. How can light influence products like milk and what does this warning mean ...
2
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1answer
389 views

Equations describing the liquifaction of gases

I would like to find out how much energy is required to liquify gases (oxygen or nitrogen, for example). What are some relevant equations? I'm curious whether creating small quantities of dry ice or ...
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3answers
714 views

What is the angular momentum spectrum of an sp${}^3$ electron?

So, one thing has been annoying me ever since I learned about orbital hybridization: you explain the shape of molecules by postulating that the orbitals of multi-electron atoms are linear combinations ...
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6answers
2k views

Where should a physicist go to learn chemistry?

I took an introductory chemistry course long ago, but the rules seemed arbitrary, and I've forgotten most of what I learned. Now that I have an undergraduate education in physics, I should be able to ...
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2answers
407 views

Explaining valence with quantum mechanics

Can anyone give me a quantum mechanical explanation of the theory of valence? (i.e. why atoms bond just enough to have a complete orbital) EDIT: To clarify, I already have an idea of why atoms bond, ...
3
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1answer
545 views

Energy levels in disordered organic semiconductors?

Now in disordered organics, the band picture is thrown out the window, from what I can tell (due to lack of symmetry). But don't HOMO/LUMO levels basically take the place of conduction/valence bands ...
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2answers
229 views

Why are the lighter halogens gases?

In the periodic table of the elements, only a few of the elements are gases at standard temperature and pressure. Those elements include the noble gases some of the halogens, and a few of the elements ...
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2answers
2k views

Why is quicksilver (mercury) liquid at room temperature?

This is a nice question when you find it out, and I am really looking for a proper answer. Take quicksilver (Hg) in the periodic table. It has one proton more than Gold (melting point 1337.33 K), and ...
2
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1answer
639 views

What is the mechanism of dielectric saturation?

It is known from experiments that the dielectric constant of a solvent might decrease in regions where there is a strong electric field, for example, near a highly charged ion in an infinitely dilute ...
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1answer
2k views

Obtain oxidation numbers from looking at electron configuration?

Suppose I know that Selenium has electron configuration $[Ar] 4s^2 3d^{10} 4p^4$. How can I use this information to then come to the conclusion that its possible oxidation states are 6, 4, 2, 1 and ...
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2answers
4k views

Why are the noble metals inert?

I am wondering: The noble 'gases' are inert because they have closed shells and don't want to give that up. But the noble metals, such as Copper, Silver, Rhodium, Gold, don't seem to have this. For ...