The tag has no usage guidance.

learn more… | top users | synonyms

11
votes
3answers
5k views

What determines the color of a pure substance and is it possible to predict it?

I have always wondered why salt is white, water is clear and gold is, well, gold. What determines the color of a substance? Does it have something to do with the electrons? And is it possible to ...
10
votes
2answers
372 views

Silicon-based life [closed]

My question may not be suitable here, because it's more of astrobiology. Life as we know it is carbon based. Is life based on silicon possible? What would the conditions for habitability for ...
8
votes
2answers
2k views

How does stuff glow in the dark?

Many things have glow in the dark properties (glow sticks, paint, toys ..), and I am wondering what is the physics behind them. How do these materials store light energy and emit it later when dark? ...
7
votes
1answer
288 views

Why does separating plastic from a cough drop create flashes?

I was tearing open individually-wrapped cough drops in the dark, and noticed that when I pulled apart two adhesive-joined pieces of silvery plastic film, small flashes of light were produced. It was ...
6
votes
5answers
2k views

Nano-particle or Molecule?

What's the difference between something being labeled a "nano-particle" or it being called a "molecule"?
4
votes
3answers
1k views

Why does a pitcher with lemon juice have foam, while one with pure water does not?

Whenever I pour water into lemon juice (pouring directly from the tap into the pitcher, not quietly along its edge) I get a foam on top: The same pitcher with water (same water tap, pitcher, time ...
4
votes
2answers
4k views

Why is oil a poor conductor of heat?

Why is oil a poor conductor of heat? Does it help in insulation?
4
votes
1answer
163 views

Why does air contain $Ar$ specifically?

Air consists roughly of $N_2$, $O_2$ and $Ar$. Why is $Ar$ the relatively common noble gas compound and not for example the lighter ones $He$ or $Ne$?
4
votes
1answer
281 views

Can we tell from periodic table that which materials are ferromagnetic?

I want to know that because I want to see whether ferromagnetic materials relate to the number of outer most electrons. If there is no direct relationship, could you please give me a list of the ...
4
votes
2answers
253 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 ...
2
votes
3answers
662 views

How do the molecules of reacting compounds proceed to form “Most Stable” molecule?

This question is a cross post from chemistry. I'm not very convinced with the answer there. So, I'm posting it here. I'm tutoring few students for Chemistry. During the course, I many times use the ...
2
votes
1answer
242 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?
2
votes
1answer
258 views

Auto-ionization of water

$HCl(g) + H_2O(l) -> H_3O^{+}(aq) + OH^{-}(aq)$ Assuming $HCl$ completely ionizes in water, if we prepare a $HCl$ solution, will the $[HCl]=[H_3O]$ ($HCl$ concentration = $H_3O$ concentration)? That ...
2
votes
2answers
105 views

How do you know which atoms are in a specific piece of matter?

If you have a piece of matter in front of you, how can you know of which atoms it consists? And starting from nothing, how can I discover all the elements (or just a lot of them) of the periodic table?...
2
votes
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 ...
2
votes
2answers
151 views

Driving a solution of optical isomer molecules with the resonant frequency

What happens when we drive a solution of optical isomer molecules (enantiomers) with a microwave radiation in resonance with the tunneling frequency of the molecules (the frequency of the transition ...
1
vote
2answers
164 views

Is it possible to mix a luminescent drink? [closed]

Is it possible to create a drink that glows? In other words, is it possible to create a non-poisonous drink that fluoresces? Are there known compounds suitable for that? If not, then what about a ...
1
vote
1answer
226 views

Buckyballs in vacuum

I've read about the idea that buckyballs and other nanostructures could be used to hold drugs and things until they reach certain places in the body and then get released. So I was wondering, if you ...
1
vote
1answer
265 views

How many wavefunctions are in a minimal basis set for benzene?

I am reading Modern Quantum Chemistry by Szabo and Ostlund and on page 62 he says "A minimal basis set for benzene consists of 72 spin orbitals." I tried to understand this number but failed. ...
1
vote
2answers
104 views

How do we represent 'smell' and 'taste' as signals?

I was wondering if we could represent 'smell' and 'taste' as signals like we do for audio. How do we mathematically represent them? Is there any research papers related to it? Can someone give me ...
1
vote
1answer
372 views

Where to find detailed measured emission spectra of all chemical elements?

I'd like to have something like this, but for single atoms and with more extended range of wavelengths. All I could find e.g. for hydrogen was lots of talks about Rydberg formula etc. and plots of ...
1
vote
1answer
1k views

Does plasma has any chemical formula?

As far as I understand, plasma is another stage of matter like solid, liquid or gas. All of these have chemical formulas, however does plasma has chemical formula as well? If it doesn't, what's made ...
1
vote
1answer
147 views

Does white phosphorous burn in ammonia? [closed]

In tonight's session of a science fiction role-playing game, I used a white phosphorous grenade against a group of ammonia-breathing aliens on their home turf, and I must confess that neither the GM ...
1
vote
1answer
218 views

Density of Solid States of Compounds

One of the wonderful properties of water (as my high school biology teacher would say) is that in its solid form, it is lighter than its liquid form. This means that when temperatures drop below 0 ...
1
vote
2answers
48 views

What causes anything to smell?

We all know that we can see anything because of Light Absorption and all. We can hear things because of caused vibrations. But what makes an object smell? I read somewhere about the presence of ...
1
vote
1answer
107 views

Molecular simulation applied to astrobiology

There is some research group which use molecular dynamics simulations to study the origin of life according to the hypothesis of abiogenesis? I'm just beginning to know this subject so I don't know ...
1
vote
1answer
50 views

Spectroscopy and the current state of our ability to determine the composition of extra-solar planets

I was interested in learning more about the status of our scientific understanding and technological instruments regarding extra solar spectroscopy. I am motivated by this almost 3 year old question/...
1
vote
1answer
44 views

Molecular formula of a compund [closed]

I have no idea on how to get information out of this one. A compound contains only hydrogen and nitrogen. Nitrogen makes up for 87.4% of the mass. A sample of this have a density of 0.977 g/L at ...
1
vote
1answer
360 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. ...
1
vote
0answers
66 views

Effects of light wavelength on the Hamiltonian of the FMO complex

Recently, I have been interested in the energy transfer within the FMO complex. I was wondering, how could the wavelength of the light that excites the complex affect the energy transfer efficiency. ...
1
vote
0answers
68 views

Alternative to Naphthalene Sublimation

I work in a wind tunnel that uses Naphthalene for flow visualization. Specifically we use it to see the location of transition from laminar to turbulent flow. We mix it with acetone and spray it on ...
1
vote
2answers
87 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 ...
0
votes
1answer
378 views

Why does the d-spacing of a polymer decrease as its crystallinity increases?

I am currently investigating the annealing of a polymer (Parylene-C). In my reading I have found that when the polymer is annealed, there is a decrease in thickness of the film which results from a ...
0
votes
2answers
395 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 http://en.wikipedia....
0
votes
1answer
329 views

A “bump” in the cooling curve of naphthalene? [closed]

While doing an experiment, I noticed a slight bump in the cooling curve. I have searched for it on the internet and all of the articles say that it is something related to super-cooling. The graph's ...
0
votes
1answer
76 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
1answer
62 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
18 views

Is the bond order in a resonance situation an average or can half bonds exist?

When drawing the lewis dot structure for $NO_2^-$ There is one double bond and one single bond so the molecule exhibits resonance and has bond order of 1.5. Does this mean the molecule shares 0.5 ...
0
votes
1answer
45 views

Why do bonds with positive and negative charges not collapse?

I previously believed that the reason positive and negative charges don't constantly attract until they collapse is due to a repulsive strong force at small distances. However, in a textbook by Tipler,...
0
votes
1answer
79 views

How is work function related to oxidation?

Low work function metals, such as Li and K, oxidize in ambient conditions, whereas high work function metals such as Au do not oxidize. In chemistry there's activation energy and reaction rate ...
0
votes
0answers
38 views

Rearrangement of oil due to high voltage electric field

I've been working on a problem for some time now and I can't figure out why exactly this happens, and I've been looking for some insight. The phenomenon can be seen in this video. We can see that the ...
0
votes
0answers
103 views

Is there any material that a magnetic field cannot penetrate? [duplicate]

Is there any way to build an enclosure that protects its contents from magnetic fields more effectively than simply keeping sources of magnetic fields away by the same distance the box would?
0
votes
0answers
55 views

Why the pressure of water at 298 Kelvin is 25 mm Hg (torr)? [closed]

Here is the problem, is about the law of Dalton. NH4NO2 decomposes giving N2 (gaseous). NH4NO2 decomposes and collects on water at 198 Kelvin and 748 atmosphere (atm). Vokume 411 ml N2. How many grams ...
0
votes
1answer
176 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 ...
0
votes
1answer
425 views

What is the name of the molecule HCCO? [closed]

I have a very hard time finding information about $HCCO$. I don't even know what it's name is. I'd like to know what its main features are, where it shows up and/or what it's used for?
-2
votes
1answer
90 views

Are all solids mono-atomic? Is there not any di-atomic metals or compounds? [closed]

I want to know whether all solids are mono-atomic or not, and if there was diatomic solids or not,and if there was compounds of solids.
-2
votes
1answer
24 views

C60 Macro Ojects

What would happen if you could make a ball or hollowed geometric shaped say the size of a basketball made out of C60.. due to its superconductivity could it have exotic or anti- effects on gravity and ...