Area 51 » Science

140

followers

Announcements

I have seen many great physics questions in here, regarding material properties, atomic physics, physical chemistry and solid state physics. Case you don't as them on physics stack exchange. – Bernardo Kyotoku Dec 4 '10 at 9:07

Members of ACS or other professional organizations need to get the news about this SE! SE is very diverse, but these are great sources of specialists. – xenomancer Mar 17 '11 at 15:56

@Bernardo: There's a great deal of overlap between chemistry and other scientific disciplines, including physics, biology, and mathematics. – Bob Murphy Apr 7 '11 at 23:44

show 1 more announcement

79 Example Questions (10 closed)

active newest votes

up vote 1 down vote

added by Gordon Gustafson, edited by WikiSpeedia hang-around Dec 20 '10 at 16:09

closed as off topic by ian93, Nick T, Cody Gray, Radu, M'vy Mar 1 '11 at 17:12

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

I'm waiting for Bernardo to claim this is a physics question. Actually, it kind of is... :-) But it certainly has implications for chemistry in fundamental ways. For instance, a given photochemical reaction requires photons with a particular minimum energy (frequency). If your light source is below that frequency, you can pump in as much power as you want and no reaction will occur. However, the wave nature of light is also important to chemists. – Bob Murphy Dec 13 '10 at 7:02

True that the wave and particle natures of light are important to chemists, but chemists don't need to study the 'why' they are the two, just be able to know that they are. As such, I wouldn't preclude a question that requires the understanding, but I think that asking directly about the duality of a photon is off-topic. – tryaria Mar 1 '11 at 23:17

@tryaria: Speaking as a chemist, I would have never gotten an adequate grade in quantum mechanics and been admitted to doctoral candidacy if I hadn't thoroughly mastered wave-particle duality. – Bob Murphy Mar 30 '11 at 4:28

up vote 1 down vote

added by Gordon Gustafson Dec 4 '10 at 0:57

up vote 1 down vote

added by John Jan 11 '11 at 19:08

Really bad newbie question, but I think it's going to get asked anyway. – John Jan 11 '11 at 19:09

up vote 1 down vote

added by PleaseStand Jan 11 '11 at 22:47

This is badly worded. It would be better to say, "What use is Bohr's model in chemistry?", and the answer is, "None, and it never has been any use." The Bohr model is a "flat" atom, and is only useful for explaining emission spectra. Bohr knew it was a practical model with no theoretical underpinnings, and he ditched it as soon as quantum mechanics came on the scene twelve years later in 1925. Chemists have never used the Bohr model for anything; we've been aware of the three-dimensional nature of molecules since at least the mid-1800s. – Bob Murphy Jan 15 '11 at 22:38

Incidentally, in the US, the Bohr model is mostly propagated in elementary school, where the teachers have little or no science background, and the textbooks aren't written by scientists. It has the advantage that it's really simple to understand, and the disadvantage that everyone in the field - including Bohr when he first invented it - has always known it was a gross oversimplification. – Bob Murphy Jan 15 '11 at 22:43

up vote 1 down vote

added by PleaseStand Jan 11 '11 at 23:02

up vote 1 down vote

added by Nick T Feb 3 '11 at 3:21

up vote 1 down vote

added by Qyuubi Feb 12 '11 at 12:59

up vote 1 down vote

added by Radu Feb 17 '11 at 4:56

up vote 1 down vote

added by Robin, edited by WikiSpeedia hang-around Feb 22 '11 at 6:38

	the broadest definition would be C(n)H2O(n), when you have the same amount of water and carbon in a molecule. Thus the carbo-hydrate name. – Cedric Mar 29 '11 at 23:16
	@Cedric: it is not the broadest definition. It would exclude sucrose (table sugar), C(12)H2O(11) (molecular formula C12H22O11). – WikiSpeedia hang-around Mar 30 '11 at 11:52

up vote 1 down vote

added by Robin, edited by WikiSpeedia hang-around Feb 22 '11 at 6:38

	You mean pi bond? – AcidFlask Feb 21 '11 at 5:27
	Excellent question with a lot of interesting ramifications. – Bob Murphy Mar 30 '11 at 3:58
	thanks......... – Robin Apr 1 '11 at 9:30

up vote 1 down vote

added by AcidFlask Feb 21 '11 at 5:44

up vote 1 down vote

added by AcidFlask Feb 21 '11 at 5:56

up vote 1 down vote

added by AcidFlask Feb 21 '11 at 6:01

I made the numbers up btw. – AcidFlask Feb 21 '11 at 6:01

up vote 1 down vote

added by Robin, edited by WikiSpeedia hang-around Feb 22 '11 at 18:12

up vote 1 down vote

added by wdkrnls, edited by WikiSpeedia hang-around Mar 30 '11 at 11:55

up vote 0 down vote

added by KennyTM Jun 9 '10 at 15:33

closed as off topic by Vortico, Tobias Kienzler, googletorp, dthorpe, ssakl Aug 17 '10 at 17:49

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

or Acidity, etc. The main point is whether question that simply asks a property of a chemical is allowed. – KennyTM Jun 9 '10 at 15:36

We don't want to make an encyclopedia. – googletorp Jun 9 '10 at 22:13

A case for the CRC Handbook? – Anonymous Oct 23 '10 at 5:49

I don't think this is a good question since you can easily find it with google. A better question would be "How do I explain the boiling point of Compound X", assuming that compound X does not follow trends. – Radu Nov 4 '10 at 3:07

Boiling point is an handbook/search case, but estimation of untabulated data are often useful. My point of view is no simple data, but how to make derivative data are good questions. – shellholic Nov 22 '10 at 17:07

up vote 0 down vote

added by Louis Rhys, edited by WikiSpeedia hang-around Dec 20 '10 at 16:16

	Duplicate / generalization of the "why is gold yellow and copper red?" question. – dthorpe Aug 23 '10 at 17:15
	Could be improved by being more specific. For instance, there are a limited number of reasons organic chemicals can be colored. – Bob Murphy Dec 1 '10 at 6:03
	The answer here is the basis of analytical chemistry - although generally outside of the visible spectrum. – tryaria Mar 1 '11 at 23:21

up vote 0 down vote

added by David Hollman Aug 31 '10 at 13:39

	Or should this be moved to a new proposed site for computational chemistry? – David Hollman Aug 31 '10 at 13:40
	I think so. This isn't really about chemistry per se. – Bob Murphy Dec 1 '10 at 6:04

up vote 0 down vote

added by JFW Nov 11 '10 at 14:20

	uh... answer is useful to many varieties of fields, including chemistry. Maybe more math like. – Bernardo Kyotoku Dec 4 '10 at 8:42
	The chemistry definition of an empirical formula is "the simplest whole number ratio of atoms of each element present in a compound". So, for instance, the empirical formula for ethane is CH3, while the molecular formula is C2H6. How one finds them is quite another story, and can involve some pretty crazy lab techniques. – Bob Murphy Jan 5 '11 at 5:27

up vote 0 down vote

added by oneat, edited by Beska Dec 1 '10 at 22:31

closed as off topic by Bob Murphy, John, glenneroo, Mad Scientist, Cody Gray Feb 8 '11 at 14:24

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

That mostly deals with biology, neurology, psychology, etc. I'm sure the chemoreceptors in our taste buds are very interesting, but they're only a small part of this question. – Bob Murphy Dec 13 '10 at 6:29

up vote 0 down vote

added by Bob Murphy Dec 3 '10 at 6:16

closed as off topic by Yasir Arsanukaev, Mad Scientist, NewName, tryaria, biLOLogy Mar 29 '11 at 19:49

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

Deliberately off-topic: really a botany question, and too vague even for that. Not to mention the bad grammar. :-) – Bob Murphy Dec 3 '10 at 6:18

up vote 0 down vote

added by WikiSpeedia hang-around Dec 20 '10 at 16:38

	(Spectrum: relative abundance of fragments as a function of mass-to-charge ratio.) – WikiSpeedia hang-around Dec 20 '10 at 16:39
	Are questions about colliding molecules in the gas phase and the consequence thereof on-topic or off-topic? – WikiSpeedia hang-around Dec 20 '10 at 16:42
	My doctoral research in physical organic chemistry involved colliding molecules in the gas phase and the consequences thereof, so I'd hope it's on-topic. :-) – Bob Murphy Jan 15 '11 at 22:54

up vote 0 down vote

added by Ravisankar S Jan 9 '11 at 13:14

up vote 0 down vote

added by Qyuubi Feb 12 '11 at 13:08

up vote 0 down vote

added by AcidFlask Feb 21 '11 at 5:40

up vote 0 down vote

added by Nuha Mar 11 '11 at 19:50

up vote 0 down vote

added by Nuha, edited by WikiSpeedia hang-around Mar 12 '11 at 21:40

up vote 0 down vote

added by Nuha, edited by WikiSpeedia hang-around Mar 12 '11 at 21:40

up vote 0 down vote

added by xenomancer Mar 15 '11 at 17:29

Very good, on-topic question. They developed over time as measurements and theoretical understanding improved. It's kind of like "why do we need both Newtonian and Einsteinian mechanics". – Bob Murphy Mar 30 '11 at 4:10

up vote 0 down vote

added by M'vy, edited by WikiSpeedia hang-around Apr 17 '11 at 18:19

up vote 0 down vote

added by Alex B Apr 20 '11 at 2:14

up vote -1 down vote

added by googletorp Jun 9 '10 at 9:20

closed as off topic by KennyTM, Vortico, Tobias Kienzler, Beska, dthorpe Aug 13 '10 at 0:21

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

	Off-topic, photons are not explained with chemistry, the use or observation of photons in a chemical reaction would be on-topic. – googletorp Jun 9 '10 at 9:21
	This would be more physics-related than chemistry. area51.stackexchange.com/proposals/1908/physics – Vortico Jun 10 '10 at 19:45
	@Vortica Since it's a very fundamental question I'd prefer it on Popular Natural Science area51.stackexchange.com/proposals/4955/… – Tobias Kienzler Jun 11 '10 at 7:32
	Definitely off-topic. However, the way photons promote electrons into higher-energy orbitals, resulting in photochemical reactions that wouldn't occur thermally, is quite interesting. – Bob Murphy Dec 1 '10 at 4:30
	Actually, the chemist's definition of what a photon is is very relevant to chemistry - particularly to physical and analytical chemistry. I don't think this is a good example of an off-topic question. – tryaria Mar 1 '11 at 23:08

up vote -1 down vote

added by KennyTM, edited by WikiSpeedia hang-around Dec 20 '10 at 16:25

closed as off topic by googletorp, Tobias Kienzler, Vortico, ssakl, dthorpe Aug 13 '10 at 0:20

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

Radioactivity by itself is not a chemistry question. – googletorp Jun 9 '10 at 22:14

it's rather (nuclear) physics. And to date not entirely answerable – Tobias Kienzler Jun 10 '10 at 7:38

I would argue that this can still be considered chemistry, since many people specifically design molecules with certain isotopes for various purposes in chemistry. Definitely a great "off-topic" example though – David Hollman Aug 31 '10 at 14:24

Despite the current votes (1 on:19 off) and my agreement with the general trend, I feel compelled to point out that Marie Curie won both the Physics and Chemistry Nobels for her work on radioactivity. – AcidFlask Feb 21 '11 at 5:36

This is an important chemistry question when you get into fields outside of pure chemistry - for example geochemistry. One of the major areas of study in geochemistry is based on radioactive decay, so understanding which elements are radioactive, and why, can be considered chemistry. I don't think we should waste one of the five example questions to point out that radiation might be better investigated in physics. – tryaria Mar 1 '11 at 23:10

show 1 more improvement suggestion

up vote -1 down vote

added by Ned Nov 17 '10 at 4:16

	physics question – Bernardo Kyotoku Dec 4 '10 at 8:28
	To estimate color, you need a lot of chemical data beyond just elemental spectroscopy. For instance, with organic compounds, you need to know the compound's 3-D molecular structure, and pay particular attention to conjugated pi bonds. – Bob Murphy Dec 13 '10 at 6:48
	Question needs some editing. @Bernardo Kyotoku this is actually an important physical and analytical chemistry question. For that matter, it has applications into organic and inorganic chemistry. Just because it deals with light doesn't make it pure physics. – tryaria Mar 1 '11 at 23:23

up vote -1 down vote

added by Gordon Gustafson Dec 4 '10 at 0:56

closed as off topic by Cody Gray, Qyuubi, Richard Terrett, ogerard, Mad Scientist Apr 16 '11 at 7:23

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

Everything. :-) – Bob Murphy Dec 13 '10 at 7:05

Seems a bit too obviously off topic. – tryaria Mar 1 '11 at 23:18

up vote -2 down vote

added by JFW Nov 11 '10 at 14:20

closed as off topic by UTChemistry, Bob Murphy, irrelephant, ian93, Borror0 Jan 16 '11 at 7:19

This question does not relate to the topic of the proposal.
It was closed as part of an automated migration of off-topic to close votes on September 29, 2011.

This is really two different questions. "What are molecular formulas" can be explained in a few minutes. "How does one get them" is very complex and people spend careers on that. – Bob Murphy Nov 30 '10 at 7:07

@Bob Murphy Just because the answer may be long winded doesn't mean that the question is bad. I agree that this should be two questions, but the second does have a standard answer. – tryaria Mar 1 '11 at 23:14

up vote -4 down vote

added by mvime, edited by WikiSpeedia hang-around Dec 20 '10 at 16:27

	This would probably be a good topic for the proposed Computational Chemistry site – David Hollman Aug 31 '10 at 14:26
	Thanks, David. I joined the proposal : ). It'd be great to have some place to post all the questions I can't get answers for in class. – mvime Sep 1 '10 at 21:43