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

learn more… | top users | synonyms (2)

1
vote
0answers
27 views

How does Passivation in Mercury-arc-valve cause “diode” behavior

Does passivation of lead anodes cause them to become semiconductors? Or even become diodes (eg. a p-n passage)? How does this work on an atomar level? This question has been risen by trying to ...
1
vote
0answers
29 views

Covalent Bonds, Varities and Limits!

Related:http://chemistry.stackexchange.com/q/9459/ I was wondering, covalent bonds tend to share two electrons, apparently rarely more than three, and normally between two electrons. Can someone give ...
1
vote
0answers
87 views

Debye Hückel Theory valid for ions?

I am wondering about the following: Is Debye Hückel Theory only used if you look at how an external "strong" field(like a potential by a sphere that has a charge that is 1000times higher than the ...
1
vote
0answers
83 views

What are characteristic ranges of time, distance, energy regions for physics and chemistry? [closed]

I've constructed such table from many different sources for my thesis introduction: I'm trying to make a bit of philosophy it the thesis first chapter. Are they realistic or not? Could you make any ...
1
vote
1answer
98 views

reactions in molecular dynamics simulations

EDIT: Apparently this is called reactive molecular dynamics. It seems that the ReaxFF potential function is used for some reactions like this. I am interested in adding support for reactions to a ...
1
vote
0answers
140 views

Leakage rate Calculation

I have to calculate leak rate for helium/air from an enclosure which is made of fabric. This is similar to helium balloons. There are small holes in the fabric. How should i proceed ?
1
vote
0answers
25 views

Solution of multiple materials

Introduction I'm trying to make some strawberry liqueur. The recipe I got says I should put alcohol, strawberries and sugar in a bowl and leave it soaking for 4-5 weeks. I read that making liqueur is ...
1
vote
0answers
34 views

Half-Life Question [duplicate]

Possible Duplicate: How do we know that some radioactive materials have a half life of millions or even billions of years? I understand how to calculate decay, but it seems to me that the ...
1
vote
1answer
482 views

What's the common consensus on the meaning of “physical change”?

I'm doing a textbook problem that shows a "molecular level" view of some matter, little colored balls, before and after, and there are, among the four questions, two that say: 1) Did a physical change ...
1
vote
0answers
98 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: ...
1
vote
5answers
6k views

Why does burning magnesium explode when sprinkled with water?

Magnesium powder burns extremely well and reaches temperatures of 2500°C. However, attempts to extinguish such a magnesium fire with conventional water (e.g. from a garden hose) only make it worse: ...
0
votes
3answers
146 views

Is duplication of nucleus, electron and proton (sub-atomic particles) possible? [closed]

usually a single cell develops into a huge mass to form a substance or an organism. is this happening because of multiplication of sub-atomic particles? if yes, then is it possible to multiply the ...
0
votes
3answers
204 views

Atoms and electrons?

Consider a copper atom. If you place an electron near it, the protons in the nucleus would attract it like they attract the existing electron in the valence shell. However the electron you placed ...
0
votes
1answer
955 views

Burning VS Melting: What is the relation in the atomic/molecular structure?

This has never been asked before on this site, so I thought I would ask this to help future searchers, passerbys, or others understand this better. What are the key differences between burning ...
0
votes
2answers
48 views

Why do corpses come back to water surfaces after sinking at first?

I want to know that why do dead bodies or corpses come back to the water surface after being sunk at first by the use of stones or anything. For what I can understand, I think it's due to water ...
0
votes
1answer
48 views

Have scientists always known that the Sun was not a fuel+air system?

Astronomy is far older than nuclear physics. So there was a long time in which fire was a reasonable explanation for the sun burning. Has any scientist figured out the sun cannot possibly be a normal ...
0
votes
1answer
35 views

Chemical reaction A+B$\leftrightarrow$C. Equilibrium VS Non Equilibrium

Could you please confirm or say why I am wrong? Let us consider the steady state of the chemical reaction $A+B \leftrightarrow^{k_+}_{k_-} C$, with $k_+$ and $k_-$ the forward and backward rates. ...
0
votes
1answer
52 views

What happens if a free radical is placed in absolute vacuum?

I'd like to know what happens if a free radical has no material around to interact with. I have asked many people but I am not satisfied with their answer. I know there is nothing like absolute ...
0
votes
2answers
15 views

Exothermic heat release mechanism in gases

How is heat released when bond formation occurs in gases? For example, when atomic oxygen and molecular oxygen combine to form ozone?
0
votes
1answer
134 views

why do we Carbonate drinks not any other gas

Carbonation is done in all fizzy drinks. Also it forms a small amount of carbonic acid which we feel on our tongue. We can diffuse oxygen as well in the water at higher level. Except for acid ...
0
votes
2answers
60 views

A question on lewis model [closed]

Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole. Isn't it a contradiction against ...
0
votes
2answers
113 views

What is “species” in the context of an electrochemical cell?

From the Wikipedia entry on Electrochemical cell (http://en.wikipedia.org/wiki/Electrochemical_cell): An electrochemical cell consists of two half-cells. Each half-cell consists of an electrode, ...
0
votes
1answer
255 views

Electrical Resistance and chemistry

Can some one describe or explain what happens when too much current is passed through lets say a copper wire, I am looking for an explanation to do with physics and chemistry. For instance we have ...
0
votes
2answers
361 views

Why are the alkali and alkaline earth metals present in the ashes of burnt wood? [closed]

The alkali earth metals form the two left-most column of the periodic table of the elements, other than hydrogen. See wikipedia articles: http://en.wikipedia.org/wiki/Alkali_metal ...
0
votes
1answer
47 views

Is Boltzmann constant $k_B$ constant?

I heard in a lecture that Boltzmann constant $k_B$ is not constant in some special cases. Do you know the title of the article which contains this one? Do you think this idea is true?
0
votes
1answer
41 views

How to thermodynamically understand process of burning a piece of coal?

Let's imagine that I have a match in hand and nugget of coal on my desk. Then I light up the match and place it for few seconds near the coal so a tiny piece of nugget catches fire. Then another piece ...
0
votes
2answers
61 views

Could we describe acids and bases using electromagnetism?

Why don't we use Maxwell's equations in acids and base theory? Surely the interaction between two charged species is readily described by this. The theory I have so far come across is HASB theory. ...
0
votes
1answer
117 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 ...
0
votes
1answer
38 views

bimolecular reaction master equation

I was wondering how to write down the deterministic rate equation for a bimolecular reaction with similar particles. e.g. $A \rightarrow^{k_+} B +B$ and $B +B \rightarrow^{k_-} A$ now the rate ...
0
votes
1answer
64 views

does there exists a rope such that it takes longer to burn the whole rope from one end? [closed]

And it takes less time to burn from the other end. The rope could be any of materials and structures and asymmetric. EDIT: But the external environment may not change during burning, and the way (eg ...
0
votes
1answer
80 views

Chemical potential in terms of temperature and pressure

For part (a), I know how to take the partial derivatives of S to get chemical potential, pressure. But there seems that I still need one equation to correctly express chemical potential in terms of ...
0
votes
1answer
49 views

Thermodynamics of zinc chloride to zinc

I am trying to deposit zinc metal from zinc chloride using chemical vapor deposition. But it is thermodynamically feasible to obtain zinc from zinc chloride?
0
votes
2answers
78 views

What is this form of notation called?

$$^{14}_6C \rightarrow ^{14}_7N + E^{-} + \bar{\nu}_e$$ Just curious!
0
votes
1answer
399 views

Are valence electrons in nonpolar molecules localized/delocalized?

Are valence electrons in non-polar molecules localized or delocalized? I'm quite confused about the whole electron localization and delocalization business. I'd love a simplified explanation that a ...
0
votes
1answer
74 views

Calculate the required water for humidity [closed]

I'm not sure if this is the right place to ask. I have a humidifier, and a closed room. Basically, I want to know the required water to reach a certain level of humidity. My room volume is 42 meter ...
0
votes
1answer
127 views

How fair is it to say that all chemistry arises from failures of the ideal gas law?

I was reading here about how the ideal gas law assumes point masses and non-interaction. Is it fair to say that all chemistry arises from failures of that? Of course, such a sweeping generalization ...
0
votes
1answer
454 views

Chemical Equilibrium - Why do changes in pressure cause a shift in the ratio of products and reactants?

I understand Le Chatelier's principle and how every change to an equilibrium system causes an opposing reaction from the system. I also understand how, when pressure is increased, the equilibrium ...
0
votes
1answer
377 views

What's the vapor pressure and evaporation enthalpy of a saline solution?

Suppose you dissolve an amount of salt in water. Because of the attraction between the ions and the water molecules, you'd expect lower vapor pressure and higher enthalpie, both depending on the ...
0
votes
1answer
57 views

Action on Lard Oil

If water is mixed with lard oil and heated (creating some super-critical liquid with water), how does this affect the volatility of the mixture in comparison with its purity..? So, My question is: ...
0
votes
1answer
50 views

Is it possible to make use of paper/bill permeate by chemical compound to became a paper-made bullet-proof vest?

Is it possible to make use of paper/bill permeate by chemical compound to became a paper-made bullet-proof vest? This is inspired by Greece and Italy tend to have more riot than rest of the Europe ...
0
votes
1answer
254 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. ...
0
votes
1answer
34 views

Question regarding NaCl equilibrium separation

So I am tutoring someone later and one of the problems is from Eisberg/Resnick Ch 12. The potential energy $V$ of NaCl can be described emperically by $$V = \frac{-e^2}{4\pi\epsilon_0 ...
0
votes
0answers
33 views

What would happen if I mix Salt and Sugar in a cup of water? [migrated]

If I mix water in a cup with sugar at some stage the solution will become saturated and no more sugar will dissolve into the water. If I now add salt to the solution will the salt dissolve into the ...
0
votes
0answers
11 views

What is the work-function of a monolayer metal on a substrate with charge redistribution at the interface?

The work-function on subsrate/metal with nm thick (or above) metal layer generally reveal the intrinsic work-funtion of bulk metal. But what if there is a monolayer thick metal, and there is charge ...
0
votes
0answers
17 views

Organisation in Periodic table [migrated]

Why We find big spaces left in the periods of the Periodic Table between H and He; Be and B, or Mg and Al? What is the logic of such organization of the periods?
0
votes
0answers
17 views

Spectral reflectance identification of types of iron rust [migrated]

According to the Wikipedia page about rust, there are red and green types of rust that occur on iron. Red rust is the reaction with oxygen and water and the green with chlorine (in oxygen poor ...
0
votes
0answers
40 views

How can I create particle-in-a-box diagrams in LaTeX? [migrated]

Interested in creating particle in box diagrams at various energy levels and dimensions. Does anyone have source code to do so or suggestions of good packages to use?
0
votes
1answer
25 views

Reaction Energy

Is the energy involved in exothermic and endothermic chemical reactions positive, negative, neutral, or something else? As in, what does it affect/come from (neutrons, protons, electrons)? Does it ...
0
votes
1answer
43 views

Why does the rate of melting of an ice block vary in different methods?

I saw that an ice block melts faster when it is placed in a microwave rather than when it is exposed to flame. Could it be because the flame creates a layer of water vapor between the flame and ice? ...