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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What happens when a semipermeable membrane allows only one solute to pass through?

I'm essentially a medical student where we deal a lot with osmosis. But when we are taught, it is done generally with only a single solute in consideration. What if two different solutes are used on ...
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0answers
10 views

What would be a suitable textbook of first semester physical chemistry? [duplicate]

I am going to take PChem I in my biochem dept next sem, which is a watered down version of the PChem course in Chem dept. It basically covers thermodynamics and a little bit of quantum stuff. The ...
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1answer
33 views

What is the relation of particle velocity, temperature, and reaction activation energy

So, this curiosity has arisen for a fun project I thought I'd tackle, where I'm attempting create a crude simulation of an internal combustion cylinder. I wanted to explore the particle level ...
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1answer
61 views

Constant Temperature Cooling

In my thermodynamics textbook there is part of a question that seems to be a contradiction. ...Superheated refrigerant R-134a at 20 C, 0.5 MPa is cooled in a piston/cylinder arrangement at constant ...
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1answer
259 views

DFT Calculations, Atomic Ionization Potentials — Which Exchange-Correlation Functional to Use, to Preserve Koopmans' Theorem?

I have a program which can perform density-functional calculations for atoms, given a density functional. Of course the simplest form of exchange potential to use is one relevant for a uniform ...
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2answers
85 views

Is there any advantage to using simple syrup over just dissolving sugar and waiting a minute?

When making coffee, I want to sweeten it with sugar. Many coffee shops offer simple syrup which is essentially just a solution of water saturated with sugar. Obviously, this has the advantage that ...
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22 views

Gibbs isotherm and calculating interfacial tension change from first principles

Question: Is it possible for a solid particle to change the surface tension between two phases? (or: Does a solid particle have a chemical potential?) This question stems from the more ...
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1answer
249 views

What happens to gas molecules after ionization?

I know that gas molecules conduct electricity after they get ionized but what will happen if we keep increasing the voltage even after ionization? Will it explode? If it will then how much energy ...
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2answers
2k views

Acer saccharum (Sugar Maple) Sap & Freezing

This may or may not be the appropriate scientific discipline to ask this question of, but I'll give it a shot. I'll happily invite chemists to chime in as well. It's time to tap sugar maples in the ...
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4answers
118 views

The impatient hot tub owner [closed]

An impatient man owns a 300 gallon hot tub. He comes home from a hard day of work and sees that his hot tub is currently simmering at 90F. For maximum relaxation, he wants it at 104F. However, the hot ...
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1answer
35 views

“Carbon capture into fuel” - where does the energy come from?

I recently found an article titled "Scientists find a way to convert Carbon Dioxide from air into fuel" (here), and my immediate reaction was "surely not - the energy balance would kill you right ...
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1answer
63 views

Calculate how many photons hitting a sample that are absorbed

In the determination of the quantum yield of a photoisomerization, $\Phi,$ the following is needed $$ \Phi = \frac{\mbox{Number of "reactions"}}{\mbox{Number of absorbed photons}} $$ The photon flux ...
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766 views

Why is salt so hard to remove from water?

Water molecules and various salt molecules are very different. However, it seems very difficult to separate the two. Once a salt is dissolved in water, an energy or chemical intensive method (like ...
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1answer
61 views

Atoms attraction [closed]

Do atoms attract to atoms of same element? And would atoms attract to another atom for forming ionic or covalent bond? I basically want to know what would an atom be attracted to? (Except for ...
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0answers
27 views

Do (or can) hydrogen bonds between water molecules neutralize their own polarity? [closed]

Do (or can) hydrogen bonds between water molecules neutralize their own polarity as indicated here: Hydrogen bonding as the mechanism that neutralizes $\mathrm{H_2 O}$ polarity ...
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1answer
70 views

Do sodium chloride(ions) melt the ice or not?

My question is this, In European countries, they use NaCl or KCl to melt ice during the winter season. In Asian Countries, they use NaCl to keep the ice without melting. (Ex- Ice cream boxes, Beer ...
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1answer
49 views

Why do randomly flying gas molecules have a distribution of energies?

Why do randomly flying gas molecules have a distribution of energies? This is a question from my chemistry textbook (not homework, just questions to help us think about and understand the concepts). ...
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1answer
36 views

How can we use conductivity measurements of water to find hydrogen ion concentration of water?

How can we use conductivity measurements of water to find the hydrogen ion ($\mathrm{H}^+$) concentration in water?
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2answers
2k 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 ...
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0answers
46 views

Why dynamic equilibrium exists?

We know that at equilibrium Gibbs energy is minimum. We also know that at equilibrium both forward and reverse reactions occur simultaneously, and also we know that for a reaction to be spontaneous ...
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1answer
12k views

Can a saltwater solution conduct electricity forever? [closed]

We know that very pure water does not conduct electricity, but salt water is a decent conductor. This is commonly explained by saying that "the ions carry the current through the solution", an ...
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1answer
104 views

What causes an emulsion to be stable or unstable?

The other day I made a salad dressing based on oil and vinegar. To my understanding, there is a positive energy associated with the surface between the oil and vinegar. The most stable state is also ...
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1answer
72 views

Electronic spectroscopy question in a more physics oriented view. What is the operator that describes relaxation pathways?

Recently I was studying spectroscopy in Symmetry and Spectroscopy: An Introduction to Vibrational and Electronic Spectroscopy p.357-358 as shown in the image http://i.stack.imgur.com/LSLyZ.jpg The ...
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3answers
164 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 ...
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2answers
184 views

Why are only Group III & V elements used for doping?

Only group III & IV are used for doping in elemental semiconductors like Si and Ge, why can't other groups be used instead?
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2answers
127 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 $O_2$? ...
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2answers
34 views

Notation in a neutron star superfluidity

In this article "Neutron Star and Superfluidity", by Ka Wai Lou: http://guava.physics.uiuc.edu/~nigel/courses/569/Essays_Fall2010/Files/lo.pdf symbols as $^1S_0$ and $^3 P_2$ are shown, but I not sure ...
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3answers
3k views

Air Regeneration in Closed Systems [closed]

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 ...
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1answer
29 views

Why higher FAT level implies more signal in XPS analysis?

In XPS analysis, the FAT (Fixed Analyzer Transmission) parameter controls the electrostatic field of an emispheric analyzer, called Pass Energy $E_P$. The FWHM of a peak of signal is given by ...
2
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1answer
112 views

Spacetime curvature effect on chemistry

Do current chemistry / astrophysics / stellar chemistry calculations include the effects of the curvature of spacetime on chemical reactions? For example, the heat transfer from a point closer to the ...
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6answers
4k 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
192 views

The NERVA had to use liquid H2… But why?

The NERVA engine, developed at the late 60ies, was a nuclear thermal rocket developed for vacuum use in space craft. It was supposed to use Liquid Hydrogen, a cryogenic fuel with quite a few issues ...
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1answer
34 views

Spin-$\frac{1}{2}$ particles in chemistry

Electrons and protons are spin-$\frac{1}{2}$ particles, so under a rotation by 360$^\circ$, their wavefunction changes by a sign. They are also commonly found alone in chemical reactions, especially ...
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28 views

Bonding Two Cationic Hydrogen Isotopes (protium) yields H2 or He?

If you have two hydrogen atoms. And they are the isotope form "Protium" (1 neutron removed) and they are also cationized +1 (1 electron removed) then you have (in a sense) a single proton (two of them ...
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1answer
36 views

What is the relation between Nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR)? [duplicate]

It seems to me that the basic principles are exactly the same, right? Then I am puzzled that the former was awarded a nobel prize while the later not. I noticed a similar question here What's the ...
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1answer
141 views

Parkhomov's E-cat reproduction [closed]

In the beginning of the year, Professor Alexander Parkhomov of Lomonosov Moscow State University claimed to have replicated (as read in e.g. Wired) of the E-cat functioning, albeit with lower effect. ...
2
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1answer
945 views

How does wax fuel a flame? [duplicate]

I get how an oil lamp runs until the fuel runs out, but a normal wax candle doesn't seem like it works the same way.
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1answer
2k views

How do candles and wicks work?

The wick of my tea candle was buried in wax. So I lit a piece of paper and stuck it in the wax. Now the wax is burning off the paper, as if that were the wick. The wax itself wouldn't light on ...
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3answers
121 views

Is there an way water can burn or cause fire?

Water known as the fire extinguisher.What is the possibility watere being the fuel to fire. "Pure water"
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1answer
24 views

Ionization Through Atomic Collisions - Any Reason(s) for Its being Unimportant?

The dominant processes which contribute to the ionisation of a gas (which is possibly hot and dense) are often deemed to be electron-impact ionization ($A + e^- \rightarrow A^+ + e^- + e^-$) and ...
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4answers
1k views

How to determine what an object is composed of?

Heads up: This question has never been asked (here) before the way I will ask it here, so let's shed some light on it a bit. Prelude and anecdote(can be skipped): The other day I was walking home, ...
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1answer
61 views

Why is blue darker than yellow in an analog black and white photograph?

Blue is perceived darker than yellow by the human eye, because of biological principles within the eye. I can understand that therefore, when making a picture black&white in software like Adobe ...
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1answer
47 views

electron shell jumping in Iron?

I understand a "little" about electron shell jumping, I was wondering about "Iron", If iron was heated to a gas, perhaps held in a vacuum maybe even under pressure, would the added energy make the ...
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3answers
332 views

Are chemical bonds matter?

So it recently blew my mind that chemical bonds have mass. And that a spring that's wound up similarly weights a little more. But there is a distinction between mass and matter. I believe that a ...
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1answer
90 views

Exothermic vs. endothermic reactions

An exothermic reaction is a chemical reaction that releases energy by light or heat. Does this mean that if I mix two chemicals in a test tube when the reaction between them is endothermic then the ...
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0answers
25 views

Charge Transport Mechanicsm of Organic Semiconductors

I understand the general concept behind inorganic semiconductors. Start with Silicon, dope the material to add an electron or a hole, and now these are free to move about in the material, creating ...
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2answers
1k views

Why heavy elements don't sink to the core?

If earth assembled out of space dust, how come we find heavy elements like gold, silver, uranium and bunch of others that are heavier than iron on the surface? I mean silicon (Si mass 28.084) being ...
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2answers
1k views

Why do some things crystallize? (And others don't, for that matter.)

Ice, for example, will form a crystal when frozen under certain circumstances. Why is this the case for ice? While on the subject of water crystallization, why do snowflakes usually form in base 6 ...
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2answers
196 views

Calculating the radius and potential energy of an atom?

Is there a general equation that gives the potential energy of any element at each energy level? I know that there is an equation for the potential energy of a hydrogen atom at each energy level but ...
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2answers
69 views

Does chemical energy contribute to mass? [duplicate]

Does chemical energy contribute to the mass of an object? I don't mean the bond energy, but the possible energy that could be released (i.e. Does an atom of oxygen and a molecule of hydrogen (H2) have ...