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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133 views

Is water a gas at critical density, room temperature?

I am quoting Chaikin, Lubensky, Principles of Condensed Matter Physics, p. 4. Now suppose we have a closed container of water vapor at a density of 0.322 g/cc at room temperature. As the ...
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109 views

Should a polyatomic crystal behave similarly to the bulk of each/either of its constituent elements?

Generally, metals are usually fairly conductive, but their oxides aren't. I know conductivity is just one attribute, but in general, should you expect a, say, diatomic bulk crystal's properties to be ...
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59 views

Slicing a surface concentration from a volumetric number concentration

Assume I have a given volumetric concentration $c$ of $N=10000$ particles in a qubic box of volume V: $$c = \frac{N}{V}$$ The units of $c$ are $$[c] = \frac{[\#]}{[m^3]}$$ Now if I introduce an ...
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257 views

Where does Computer Science background students fit in Theoretical Physics [closed]

I am basically an Electronics student - background in computer science (that's where I want to work). I applied for an internship in USA in a research institute where the group is focused in ...
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1answer
152 views

Searching the point group of symmetry

I am engaged in the field of quantum-chemical calculations using programs written by myself. I have found out that I have a problem in finding the point group symmetry of the molecule. The first idea ...
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2k views

How much disolved oxygen is removed by boiling water?

Apologies if this is a chemistry question I've read that drinking water contains dissolved oxygen to the tune of $10\:\rm{ppm}$. I've also read that raising the temperature of water will remove some ...
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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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104 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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6k 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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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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26 views

Linear decrease in temperature during a redox reaction?

This is physics-related, don't worry. To calculate the enthalpy change of a solution during a redox reaction, what we did in class was measure the temperature of the solution every 30 seconds (before, ...
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50 views

Solar still and how it works

I use a solar still that holds 182 cubic feet of water. Here is how it works: There is an insulator on both sides of the metal bowl. On the outside it covers the whole thing. on the inside it covers ...
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21 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 ...
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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 ...
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17 views

Calculate Avogadro's constant based on grating constant and density of NaCl crystal [closed]

The tittle says it all. I need to calculate Avogadro's constant based on grating constant of NaCl crystal ( in this case 278 micrometers ) and crystal density ( 2.1 grams per cubic centimeter ).
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55 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 ...
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79 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 ...
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113 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 ?
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24 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 ...
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29 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 ...
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402 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 ...
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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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69 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 ...
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130 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 ...
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253 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 ...
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40 views

Intermolecular Hydrogen Bonding

I learnt about intermolecular hydrogen bonding today, which occurs between molecules such as ortho-nitro-phenol. What I was told is that in case of intermolecular bonding, the molecules separate from ...
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119 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 ...
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56 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 ...
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88 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, ...
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219 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 ...
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328 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 ...
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59 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 ...
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36 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 ...
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43 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?
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75 views

What is this form of notation called?

$$^{14}_6C \rightarrow ^{14}_7N + E^{-} + \bar{\nu}_e$$ Just curious!
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165 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 ...
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65 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 ...
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121 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 ...
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329 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 ...
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280 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 ...
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2k views

How does one calculate the volume of a nucleus and the volume of an atom (in this case hydrogen)?

The hydrogen atom contains 1 proton and 1 electron. The radius of the proton is approximately 1.0 fm (femtometers), and the radius of the hydrogen atom is approximately 53 pm (picometers).
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53 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: ...
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48 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 ...
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190 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. ...
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57 views

Milk-First School

I have always been struck by the huge amount of different arguments about the issue: When you make a cup of tea, the milk should be poured first or added to the cup after the tea? Wikipedia, ...
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1answer
17 views

Conductivity of Aqueous Ionic Solutions as a Function of Time

It is well-known that an aqueous ionic solution can conduct electricity. Let's take the electrolyte NaCl for example. In the diagram below, the circuit consists of a voltage source, a light bulb, and ...
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46 views

On Thermodynamics of Spontaneity of the Reduction-Oxidation Chemical Reactions

According to the first and second law for a closed system containing different chemicals we have \begin{align} &\delta Q - \delta W = dU = T dS - p dV +\sum_i \mu_i d N_i\\ ...
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52 views

Melting and Boiling Points of Odd Materials

In Chemistry, I was taught that there are three main states of matter: solid, liquid, and gas, and that heat and pressure determine that state. For some substances, the line is blurry between them. ...
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53 views

In what sense can an object in outer space be “on fire”?

The famous "Tears in rain" soliloquy in Blade Runner goes like this: I've... seen things you people wouldn't believe... [contemptuous laugh] Attack ships on fire off the shoulder of Orion. I ...