Wikipedia:Reference desk/Archives/Science/2008 January 16

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January 16

Simple decomposition question

When dilute hydrogen peroxide is placed inside a test tube and NaOH and fresh cow liver is added to it to speed up its rate of decomposition, is the NaOH considered an enzyme? The liver for sure is an enzyme, but is the NaOH considered one as well? Acceptable (talk) 00:18, 16 January 2008 (UTC)

An enzyme is a protein that catalyzes a reaction. Since NaOH is not a protein, it cannot be an enzyme. On the other hand, it would be called a catalyst, which is a more general term.

Although the liver obviously contains catalase, can someone else tell me what the function of the hydroxide would be?.. I'm thinking that would just denature the catalase.18.96.5.239 (talk) 00:49, 16 January 2008 (UTC)

Catalase functions optimally in a basic solution. I wouldn't call this a catalytic effect, just a pH effect. Someguy1221 (talk) 03:54, 16 January 2008 (UTC)

Water density fluctuations?!?

Hi. Recently I did an experiment in a group. We poured water into a graduated cylinder (it was supposed to be 10ml at a time but we messed up). We discovered that although the mass of the water went up, it jumped back down then kept going back up. What's with the anomaly? Why was the density always under 1 g/cm³? I think we used tap water. Why the anomaly? Can you tell by the graph? Is it experimental design flaw? Did we mess up on something? Was it an alien invasion? We measured the mass of the cylinder prior to the experiment, then subtracted it to find the actual liquid mass. What's going on? Here's the image. Sorry about the messiness. Thanks.

The graph

~AH1^(TCU) 00:41, 16 January 2008 (UTC)

Mass cannot change like that. Looks like very poor experimental technique to me (probably errors in the weighing)--TreeSmiler (talk) 00:46, 16 January 2008 (UTC)

If you were putting the tared graduated cylinder on the scale and letting it sit there, air currents can easily cause the mass to fluctuate. This is why more precise, analytical balances have glass walls around, to prevent mass fluctuations due to air currents. I have no idea what would cause the mass to be off by that much, though. Maybe you were hovering around the balance and touched it in some way. Or maybe the balance itself is broken. (Did the entire class use a single balance, and did other people have the same troubles?)18.96.5.239 (talk) 00:49, 16 January 2008 (UTC)

(edit conflict)Hi. Well, we used a balancing scale. We had to shift the 100g block first, then the 10g block, then the smaller block that can be shifted at intervals as small as 0.1g. If you want to know what happened between approximately 36g and 50g, at first I used a small 10ml cup for measuring, but it wasn't accurate because by the time I had 5 x 10g, it barely exceeded 40ml on the cylinder. So, I added more water, but it spilt. We cleaned it off, then put the cylinder back on, then I filled the cylinder until the bottom of the meniscus was at about 50ml. I don't think it is the error in the first half of the slope, because that was actually close to the expected result, and I don't think it was in the second half, because the slope continued without any other abberant data. Is the density of tap water different from distilled water? Where do you think we messed up? It did take about a whole minute to adjust the scale so it would give us a reading. Oh, and this question in particular is not homework. Also, I hope you don't mind that I simply changed the destination filename to jpg whereas it was previously bmp. Thanks. ~AH1^(TCU) 00:57, 16 January 2008 (UTC)

Maybe heres some of the things your experiment was designed to show. [1] —Preceding unsigned comment added by TreeSmiler (talk • contribs) 00:58, 16 January 2008 (UTC)

(edit conflict)Hi. Well, even if I did touch it, the babance would simply swerve, then we might have to readjust the micro wieght. The first balance we tried was broken, all the data was used with the second balance. We all used different balances and I don't think they had much trouble unless they forgot to subtract the mass of teh cylinder. Thanks. ~AH1^(TCU) 01:01, 16 January 2008 (UTC)

Well, the page says stuff about temperature, ice, pressure, etc. The temperature was pretty much constant, there was no ice, and if anything adding more water should increase its pressure/density, not lower it, so I don't see how that page explains this huge anomaly. Thanks. ~AH1^(TCU) 01:06, 16 January 2008 (UTC)

From the shape of the graph, I'd say that the most likely cause is the zero point of the balance shifting. --Carnildo (talk) 01:22, 16 January 2008 (UTC)

Hi. By the zero point do you mean the mark that says "0" on the side of the scale, that lines up with the end of the balance opposite the round plate where you place the object to be weighed, that looks like an elongated axe? Well, the "axe-like" part can shift, but to change its position from too high to too low from the 0 mark would only take a shift of several grams on the micro weight. Or, do you mean something in the system shifting? Where should this be and how can it happen? Does something fall off? Thanks. ~AH1^(TCU) 01:30, 16 January 2008 (UTC)

Most measuring devices have a way of adjusting the readout so that they read "0" somewhere other than when it isn't measuring anything. For example, the balance you're using might have a small weight that can be moved back and forth. If that was shifted between when you made the 35ml measurement and when you made the 50ml measurement, the result could be the jump in the graph. --Carnildo (talk) 23:13, 16 January 2008 (UTC)

Towel snapping, water, and pain

Someone told me that when people snap towels at each other, as kids - and probably adults - do at tiems in locker rooms, it stings more when the skin hit is wet. I think that makes sense, but why? I'm guessing water, being a condutor of electricity, might also be a good conductor for pain neurons, and thus the sting lasts longer? Also, why does one's skin get red when this happens - this seems pretty easy to me, the breaking of those tiny capillaries, right?63.3.19.1 (talk) 01:59, 16 January 2008 (UTC)

It doesn't have anything to do with conductivity of pain neurons; the neurons themselves are well below the skin and do not get wet when the skin is wet. --24.147.69.31 (talk) 02:02, 16 January 2008 (UTC)

It seems far more likely that the wetness of the towel is what matters, as that's what gives the towel tip sufficient mass to make a meaningful impact. — Lomn 07:18, 16 January 2008 (UTC)

It also makes the towel more... solid I guess. Compare how a wet towl feels to touch compared to a dry towlTheGreatZorko (talk) 14:18, 16 January 2008 (UTC)

I don't think it's only the wetness of the towel that counts. If you hit someone's unclothed back with your palm (not a towel), it hurts much more if his or her back is wet. – b_jonas 17:29, 17 January 2008 (UTC)

But, if it's not the water somehow dispersing the pain, what causes that?63.3.19.129 (talk) 22:08, 22 January 2008 (UTC)

Energy determination

I'm trying to measure the BTU capacity of various torches and soldering irons, etc. both gas and electric according to the standard of 1 degree Fahrenheit temperature increase per pound of water. Is there a formula that I can use instead based on the total reduction in lbs of liquid water after I have applied heat? In other words if I have 2 lbs of liquid water and heat it with a candle until the candle is consumed determine the energy in the candle by simple measuring how much water the candle has evaporated? —Preceding unsigned comment added by 71.100.12.59 (talk) 04:39, 16 January 2008 (UTC)

Not reliably. Different experimental setups will have varying rates of evaporation (surface area affects this), which is enough to invalidate the attempt. Worse, though, is that a setup like you describe doesn't constrain the candle's energy to the water -- heat is free to radiate in all directions, most of which don't result in any measurement on your part. — Lomn 07:23, 16 January 2008 (UTC)

You would get a more accurate result if, instead of trying to evaporate the water, you just heated it inside a container. Then you could measure the temperature rise of the water and estimate the energy it had absorbed. This is the basis of the bomb calorimeter; and don't worry, it's not as dangerous as it sounds. --Heron (talk) 20:51, 16 January 2008 (UTC)

'Company doctor'

If someone is or may be infected as a result of research activities of a co-inhabitant, should they see the "company doctor" of their research establishment or a regular doctor? I'm trying to understand the idea of a "company doctor". ----Seans Potato Business 11:42, 16 January 2008 (UTC)

Did you have a school nurse when you went to school? Same idea. Some companies find it cheaper to put a doctor on retainer - even having the doctor show up at an office inside the company building - rather than throwing money at insurance and having employees take time off work to spend half the day waiting to see some other doctor. There are opinions that a company doctor is a good thing. There are opinions that a company doctor is a bad thing. -- kainaw™ 13:28, 16 January 2008 (UTC)

Also, is the core of your question simply "what is a company doctor?" or is it the opening sentence about "should you opt for the company doctor if your buddy's research turns you into the Hulk?" Those are two very different questions, after all. As for the latter, it's likely that employees have considerable rights in the event of such an occurrence. OSHA would be one place to check that sort of stuff (for those in the US, or, apparently, the EU. Who knew?), and the company's HR department should be well-versed in the particulars. — Lomn 13:53, 16 January 2008 (UTC)

The company's HR department (whatever happened to personnel?) will have a view, but you may find it worthwile to speak to your union rep too. DuncanHill (talk) 14:01, 16 January 2008 (UTC)

An onsite physician may be better-versed in the hazards of your particular workplace and may also be able to see you on shorter notice (and in a more convenient time and place) than an offsite doctor. On the flip side of the issue, a company doctor may face conflict-of-interest issues in dealing with or reporting workplace injuries and mishaps, and may or may not have the resources of a larger clinic or hospital.

In all cases, you should seek the advice of a physician with whom you feel comfortable. If you are concerned about a health and safety issue at work (particularly one related to (mis)handling of infectious materials) there are likely to be statutory requirements for you to report the issue to a manager or company biosafety officer. If you are in a unionized workplace, your union rep would be a good person to speak to, as well. Your human resources department may become involved.

If you suspect (or know) that you have been injured or infected through the negligence of another person in your workplace, keep meticulous records (with a copy stored offsite) of everything that you know (or believe) has happened, and of every document you send or receive. Such records may be invaluable for internal or external investigation of the problem, or during a civil or criminal trial. If you feel the need for specific legal advice, you should ask a lawyer who has experience in employment law. TenOfAllTrades(talk) 15:40, 16 January 2008 (UTC)

a company doctor may face conflict-of-interest issues in dealing with or reporting workplace injuries and mishaps. Too right. I knew someone who broke their arm at my place-of-work-at-the-time, and all the company doctor did was ensure they signed some forms indicating they wouldn't sue and it wasn't the company's fault, before calling an ambulance. 79.66.24.40 (talk) 16:45, 17 January 2008 (UTC)

ARUN S BAGH QUES ABOUT PLUTO

why is pluto exactly called 134340? —Preceding unsigned comment added by 59.95.176.209 (talk) 14:17, 16 January 2008 (UTC)

See Astronomical naming conventions#Minor planets and Pluto#IAU decision to reclassify Pluto. The latter states "If Pluto had been given a minor planet name upon its discovery, the number would have been a little over a thousand rather than over 100,000." - Dammit (talk) 14:51, 16 January 2008 (UTC)

In other words, they looked deep within Pluto's soul, and assigned it a number based on the order in which it joined. -- Coneslayer (talk) 15:11, 16 January 2008 (UTC)

"It comes after 134339, hon." --Anon, 00:37 UTC, January 17, 2008.

Pluto's discovery date (February 18, 1930) falls between the discovery dates of 1163 Saga (January 20, 1930) and 1164 Kobolda (March 19, 1930) - so a sequential number based on discovery date would have to be something like "1163a", or maybe "1163 ½". Looking at List of asteroids/134001–135000, the objects either side of 134340 Pluto are the unnamed objects 134339 discovered on October 16, 1977 and 134341 discovered on June 25, 1979 - but I believe a sequence number is only assigned once an object's exact orbit is determined, which may be some time after discovery. Gandalf61 (talk) 14:29, 17 January 2008 (UTC)

Oh, that is interesting. I assumed that the number was simply the next one available after the supposed demotion of Pluto. Instead it turns out to be a number from exactly the time when Charon was discovered, which led to the computation of Pluto's mass, which was the motive for the event. Did someone actually assign then number 134340 back then, and wait almost 30 years for their evil views to receive official acceptance? (Just remember, all you people who go around editing articles to change planet to dwarf planet ... your planet could be be next, and then who will be left to speak for you?) --Anonymous Pluto partisan, 18:35 UTC, January 17.

No: these asteroids were discovered in that time, yes, but their orbits were not known precisely enough for them to receive official numbers until around the time Pluto got demoted. So indeed, 134340 was simply the next number available. Double sharp (talk) 09:28, 17 July 2014 (UTC)

Most Toxic

What is the most deadly toxin or poison in the world? By most deadly I mean can kill with the least amount. DTWATKINS (talk) 14:45, 16 January 2008 (UTC)

I think this has come up before. You'll find a useful discussion in Wikipedia:Reference desk/Archives/Miscellaneous/2007 October 16#Most toxic toxin. Cheers! TenOfAllTrades(talk) 15:23, 16 January 2008 (UTC)

Depending on the level of pedantry, oxygen gas kills with a concentration of zero. You might be interested in LD₅₀ and related articles, or you could check the archives for the many many times this has been asked before. TenOfAllTrades cites one of the recent ones above. — Lomn 15:25, 16 January 2008 (UTC)

You didn't specify the time which may pass between ingestion and death. In experiments with rats, mice etc. it's commonly 48 hours. Really short-lived radionuclides would kill in smaller amounts than botulinum toxin, e.g. francium-210 (from my answer to the old question and a table of nuclides I conclude that the LD-50 within 48 hours should be maybe 30 pg/kg, but this comes with a large uncertainty), but they're hard to synthesize in larger amounts and you'll have to be fast to try them before they decay... Icek (talk) 15:30, 16 January 2008 (UTC)

Plutonium is often refered to as the most toxic substance known to man. Whether this is the case or not is debatable. There is a pretty good discussion about toxicity in that article on Plutonium. -- Saukkomies 10:49, 16 January 2008 (UTC)

Um, it's not really that debatable. It's not the most toxic under any reasonable definition. It's toxic, for sure, and can cause major health problems if inhaled, but it's not a good choice to poison someone with, which is a sure sign of its lack of being in the running for "most toxic". --24.147.69.31 (talk) 15:54, 16 January 2008 (UTC)

It's all about how you use it. A few kilograms of plutonium can kill an awfully large number of people.  ;-) Dragons flight (talk) 17:46, 16 January 2008 (UTC)

Wink all you want, but that's not toxicity, and a few kilograms of plutonium by itself does nothing unless you have a lot of other apparatus. And even if you did take that definition of it, it is still nothing compared to botulinium toxin, where "a few hundred grams could theoretically kill every human on earth". Even taken for its role in nuclear weapons, pound for pound it's still not even in the running for most toxic substance!! --24.147.69.31 (talk) 18:04, 16 January 2008 (UTC)

The reason that plutonium being considered the most toxic substance is debatable is due to the fact that it has the ability to sustain its toxicity for a very very long time. Most poisonous/toxic substances kill or maim their victims and then are depleted or used up in the process. Plutonium, on the other hand, has a very long half life (80 million years or so, give or take a decade), which means that it will continue to be highly toxic for ... well ... forever basically. So, if say a major earthquake took out one of the dams on the Columbia/Snake River system above the Hanford Site, which has quite a bit of plutonium on its premises, there could theoretically be a resulting chain reaction of dam failures all the way down the Columbia River to the Pacific Ocean, with the flood waters also theoretically carrying much of the plutonium from Hanford. If such a calamity was to take place the result would be that a largish amount of plutonium would be dumped with the flood into the Pacific, resulting over time in destroying all life in the entire Pacific Ocean basin as the ocean currents spread it around. The reason for this is not because plutonium is highly toxic immediately, but because of its very long-lasting quality which means it continues to kill and kill and kill without being consumed or destroyed in the process.

THAT is the reason that some people use to support the thesis that plutonium is the most toxic substance known to man, and that is why it is debatable. It all depends on what you mean when you say something is toxic - do you mean is it toxic in the short term or the long term. If in the short term, then plutonium is not the most toxic. But if you mean what is the most toxic substance in the long term, then plutonium wins hands-down as being the most toxic substance. -- Saukkomies 08:30, 17 January 2008 (UTC)

No, the reason some people support that "thesis" is that they want to frighten people by irrational arguments. They seem to have succeeded with you. --Anon, 17:46 UTC, January 17.

Have you ever heard of the concept of concentration? If you were to dump the entire contents of the Hanford holding tanks into the Pacific and mix well, the average glass of water would contain no plutonium. The Hanford tanks may be large on a human scale, but on a human scale, the Pacific is bloody huge and then some. --Carnildo (talk) 21:49, 17 January 2008 (UTC)

Well, the average glass of water would contain some plutonium, but not enough to worry about.

As for Saukkomies's point about the lifetime of the substance -- elemental poisons, such as lead or arsenic, last forever (or close enough for government work--I'm not taking proton decay into account, obviously). Many other industrial poisons and carcinogens, such as polycyclic condensed aromatics or dioxins, might degrade eventually, but not soon enough to consider them a temporary problem. Basically I can't see plutonium at the top of any list of nasties not involving intentional aggression. I think it's important to refute this meme about plutonium, which is a very dangerous one, as it could prevent the expansion of nuclear power, which is one of our best hopes for reducing carbon emissions. --Trovatore (talk) 22:08, 17 January 2008 (UTC)

No, the average glass of water would not contain 'any plutonium. The basis of atomic theory is that matter is not infinitely dividable: once the concentration of plutonium drops below one atom per two cups, the average cup of water won't contain any plutonium. --Carnildo (talk) 22:48, 18 January 2008 (UTC)

I do understand about the non-infinite-divisibility of plutonium. Do you understand the magnitudes involved? In 239 grams of Pu-239, there are Avogadro's number -- 6x10²³ atoms -- of plutonium. That many cups of water would weigh 3x10²³ pounds, or around 2% of the mass of the Earth as a whole. The ocean is not very deep; from the point of view of the whole Earth it's just a little wet spot. And there's a lot more plutonium than that in Hanford. --Trovatore (talk) 07:18, 19 January 2008 (UTC)

(Margin readjusted)

Okay, first off, plutonium is not necessarily connected with nuclear energy. There are plenty of nuclear reactors that do not use plutonium and do not make plutonium. So the point about being aware of plutonium's nasty nature has very little bearing on that subject.

Second, per the discussion about plutonium being able to kill off all life in an ocean basin, please refer to the various articles published in peer-reviewed professional/academic journals that basically state how this is a possibility:
- "Plutonium protest", by Cheftel, Julia. Chemistry & Industry no20 (October 18 2004)
- "Disposing of the world's excess plutonium", by McCormick, James M.; Bullen, Daniel B. Policy Studies Journal v. 26 no4 (Winter 1998) p. 682-702
- "A sea of troubles: how plutonium came back to plague us", by Busby, Chris. The Ecologist v. 29 no7 (Nov. 1999) p. 396-7
- "Pu by the ton", by Moore, Mike. The Bulletin of the Atomic Scientists v. 53 (March/April 1997) p. 44

The Reference Desk is not meant to be used as a forum for people to push their own personal agenda or theories, so unless someone has any solid proof that refutes the fact that plutonium is capable of destroying life in an ocean basin (as is outlined in above cited journal articles), then I would suggest the discussion be taken elsewhere, as it is merely opinion. -- Saukkomies 17:32, 17 January 2008 (UTC)

So it's not true that the question has little bearing on the subject of nuclear power. Right now we're using uranium reactors, but it stands to reason that if nuclear power is to substitute the role currently played by fossil fuel, we will eventually need breeders.

However I concede that I haven't read those articles and can't directly comment on them. --Trovatore (talk) 22:57, 17 January 2008 (UTC)

Sigh. I'll check out the articles tomorrow, why not. In the meantime, plutonium is STILL not in the running for "most toxic". There are PLENTY of more toxic things. The question is not whether it is toxic but whether it is "the most toxic substance in the world." It is NOT. It is not even CLOSE. You need thousands of times more plutonium to be toxic as you do some other substances. Nobody is denying that plutonium is not something you want in a water supply or something dangerous to handle, that's clear. But the nonsense about it being "the most toxic" is factually incorrect. Nobody with half a brain should defend it, even if they don't support nuclear power. (I'm not nuclear advocate, but nonsense is nonsense!) And to claim that the question of plutonium's toxicity has nothing to do with nuclear power is just disingenuous and you know it. The "most toxic" fallacy is repeated over and over by anti-nuclear advocates. It's not a coincidence. --24.147.69.31 (talk) 04:28, 18 January 2008 (UTC)

I think it's time to either let this discussion die or take it somewhere else. My point that plutonium being the most toxic substance being debatable has only been further supported by the continuing debate that it seems to be inspiring. As soon as people begin to put others down and start calling each other names it is time to stop the discussion and get on with other things. That's all I will post to this subject. -- Saukkomies 07:46, 18 January 2008 (UTC)

It's not debatable in any real sense; it's only debatable because you don't know what you're talking about and are willing to debate it endlessly. All of those articles about dumping of extremely large stores of plutonium at best—the title "Pu by the ton" spells that out pretty clearly. Toxicity is a factor of how much of a material is toxic. Plutonium just isn't very toxic compared to many other things. As a long-lived radioactive element that makes sense: it's radioactive dangers come from it being weakly radioactive but persistent. A little bit in your lungs will radiate and radiate and eventually might give you cancer according to a probabilistic model. That's no good, everybody agrees. But that's not how toxicity is defined. A speck of Polonium-210 in your presence will kill you dead within days if not hours. That's toxic. As I pointed out, with plutonium, even in its arguably "most toxic" form—used in nuclear weapons—it's pound-for-pound not as toxic as a lot of things. That doesn't make it safe, nobody is arguing that. But it doesn't hold any mantle for "most toxic" and no amount of grandstanding or twisting of words can change that. Plutonium has a lot of things going for it to make it something one doesn't want to handle—it is chemically complicated, it is weakly radioactive and thus long-lasting, it is a very heavy metal, it is pyrophoric, etc.—but it's not really all that toxic. The famous challenge of course is for you to eat as much pure caffeine as I could plutonium. You'd die first, and I probably wouldn't die at all—most of it would pass out of my system unabsorbed, and that which remained would only raise my chance of cancer by a small amount. The caffeine would kill you dead, and quickly.

It's clear that the "most toxic" line has been spuriously put out there by anti-nuclear advocates (starting with Ralph Nader) for the purpose of trying to scare people away from nuclear power. Personally I think it hurts their cause more than it helps it—putting out factually incorrect information just makes it all the easier to not be taken seriously, whereas what we need on the nuclear power is more of each side stepping back from their ideological talking points and really trying to make good decisions about what people need and what type of technological risks our societies find worth taking. You won't find that, though, when people are committed to repeating fables, and it just makes all sides frustrated.

I'll admit it—I don't think you're being intellectually honest here. --24.147.69.31 (talk) 16:16, 18 January 2008 (UTC)

It's really annoying to see how myths persist for so long. --Taraborn (talk) 11:23, 19 January 2008 (UTC)

Salty water

I was surprised to realise I didn't know why sea water is salty, so looked up Seawater.

I understand Halley's theory (my inexpert summary: salts leached from ground by run-off go into the sea) but the next parag flummoxed me:

Halley's theory is partly correct. In addition, sodium was leached out of the ocean floor when the oceans first formed. The presence of the other dominant ion of salt, chloride, results from "outgassing" of chloride (as hydrochloric acid) with other gases from Earth's interior via volcanos and hydrothermal vents. The sodium and chloride ions subsequently became the most abundant constituents of sea salt.

None of this makes any sense to me - can it be explained here and in the article? --Dweller (talk) 15:25, 16 January 2008 (UTC)

Well, salt is chemically composed of two ions (two charged atoms), sodium and chloride (making sodium chloride, written chemically as NaCl). All it's saying, once you know that, is that there was a lot of sodium in the ocean floor and that a lot of chloride was released through vents and volcanos, and these combined to make salt in the water, thus became salt water. --24.147.69.31 (talk) 15:42, 16 January 2008 (UTC)

Also, salts leached by groundwater are actually coming from salt deposits layed down by ancient extinct seas that are now located in land that is above sea level. Salt is created in the ocean (see the above response for this), not on dry land, and therefore if it is found on dry land, it is an indication that that portion of land used to be underwater at some point in the geologic past. Because salt does not evaporate, it is left behind when water evaporates into the atmosphere. This is also why salt is in the oceans - it cannot escape because it is in the bottom of the drainage system of the world's water cycle. When water evaporates from inland seas it leaves large deposits of salt behind, which then over time get covered by other soils and form salt deposits. -- Saukkomies 10:59, 16 Janyary 2008 (UTC)

Ah! Among other things that confused me, was "leached out of the ocean floor". I thought it was saying it leached from the ocean to... somewhere else (gawd knows). All of the above makes sense. If someone who understands what they're talking about and can string a sentence together (either of you guys, for starters!) could improve the article that'd be great. --Dweller (talk) 16:07, 16 January 2008 (UTC)

determination of percentage for aspirin

how do we determine the percentage of aspirin and why? —Preceding unsigned comment added by 82.146.171.139 (talk) 18:46, 16 January 2008 (UTC)

What do you mean by "percentage of aspirin"? -- Coneslayer (talk) 19:21, 16 January 2008 (UTC)

Sounds like a homework problem. I'd use a balance scale to determine the mass of an aspirin tablet, then compare that against the reported milligrams of active ingredient in the tablet. A little math, and you've got a percentage. --Mdwyer (talk) 23:59, 17 January 2008 (UTC)

Does stretching a muscle increase muscle mass?

Hi, Suppose subject A has a hamstring muscle that weighs 3.0 lbs. Subject A proceeds to stretch that muscle over a period of a month, say. So that the muscle is now 1.05 times the length than before. Does this stretched muscle grow larger so that the muscle now weighs more than 3.0 lbs? Or does the muscle stretch out and become thinner, so that the muscle stills weighs 3.0 lbs?

I ask this question because in stretching muscles I often feel a kind of burning sensation, as if I were working out. Also, after stretching, some of my muscles do feel a little sore (in a good way).

Thanks! --InverseSubstance (talk) 19:32, 16 January 2008 (UTC)

Stretching is not a recognised way for Muscle building. Instead contracting muscles under load can boost mucle mass. (eg weightlifting) Graeme Bartlett (talk) 01:43, 18 January 2008 (UTC)

Actually the relevant WP article is at strength training; weightlifting, according to the article, is a sport rather than an exercise. Not sure that agrees with common usage, but I suppose it's a sensible distinction. --Trovatore (talk) 01:48, 18 January 2008 (UTC)

Car polution

Why dont we just put CO2 filters in the exhaust pipe of cars. —Preceding unsigned comment added by Sivad4991 (talk • contribs) 20:12, 16 January 2008 (UTC)

Filtering it from the air doesn't stop it from being made. Bellum et Pax (talk) 20:17, 16 January 2008 (UTC)

what, by that reasoning having all the pollution in the air worldwide in a huge, giant (very large) vault next to Fort Knox wouldn't give us cleaner air. Of course it would, and the question is a legitimate one. Reducing air pollution is about...reducing air pollution. —Preceding unsigned comment added by 212.51.122.4 (talk) 20:26, 16 January 2008 (UTC)

The key question , of course, is: "Having filtered it out, where does the car store it? And then where do you put it?" Our article about carbon sequestration may help to provide some answers about the latter half of the question but even the first half requires tricky technology. A big tank of lime water maybe?

Atlant (talk) 20:50, 16 January 2008 (UTC)

Not quite the same but a lambda sensor work on making a car more emission efficient. This forum posting (http://forum.physorg.com/index.php?showtopic=5478) seems to go into more details about CO2 filters from a "would they work" viewpoint.ny156uk (talk) 20:38, 16 January 2008 (UTC)

A) There aren't any efficient, small-scale filters specifically for CO2. B) Even if you could trap all the CO2, it would be quite hard to store. At atmospheric pressure you'd need about 10 m^3 of space for each gallon of gasoline. An onboard gas compressor wouldn't be impossible, but greatly increases the technical difficulty. By comparison, the catalytic converters on a car improves exhaust by passively converting some toxic gases into less toxic gases. No energy input is required and the results still get dumped into the air. Unfortunately, because CO2 is already fully oxidized there is no easy way to convert it into anything else. Dragons flight (talk) 20:53, 16 January 2008 (UTC)

self-heating food

so if I want to drink coffee hot that I prepare in the morning I can bring a small thermos with me. what can I bring that almost fits in a pocket that gets warm or stays warm, like an mre. —Preceding unsigned comment added by 212.51.122.4 (talk) 20:22, 16 January 2008 (UTC)

Something in a Self-heating can, perhaps? --LarryMac | Talk 20:30, 16 January 2008 (UTC)

yeah but does it have to be a can? i dont want to eat my gourmet spaghetti creation I made in the morning and that beats the local options where I work...from a can. What can I do? in my case, I think something exothermic I can mix into my tuppperware and stir around a bit would work fine. Does anything self-heat? —Preceding unsigned comment added by 212.51.122.4 (talk) 20:57, 16 January 2008 (UTC)

In general, exothermic substances are also going to be toxic/caustic. Self-heating cans, and the like, are able to work because the heating element is seperated from the food by barrier. Dragons flight (talk) 21:04, 16 January 2008 (UTC)

I was thinking, like little sealed balls I could mix with my food for a while, and then just not eat those. or, a sealed container (not a can!) that self-heats from a reaction in a sealed-off part. If MRE's can self-heat, why can't i buy something that does the same thing. is it a controlled substance or dangerous or something, hence only suitable for soldiers. thank you! —Preceding unsigned comment added by 212.51.122.4 (talk) 23:21, 16 January 2008 (UTC)

It appears you can buy the "ZestoTherm" heating pouches used with MREs for $10 / dozen from camping/survival stores. For example: [2]

To answer the other point, yes, the things are potentially dangerous. The calcium oxide used in many self-heating cans will eat away skin. It appears that the MREs version uses less dangerous chemicals, but even so it should also be treated with respect. Dragons flight (talk) 00:27, 17 January 2008 (UTC)

A hamster or a mouse or small kitten?--TreeSmiler (talk) 01:44, 17 January 2008 (UTC)

One can get wide-necked thermos flasks for food. DuncanHill (talk) 22:18, 17 January 2008 (UTC)

Memory Battery

are memory batteries for cell phones real or are they a myth 'EDIT': what i meant was do the batteries that come with a phone have a memory function so that it requires you to use your battery until its dead before you can charge it again. i9 have heard people say the if you dont let you battery run down before charging it again you will shorten the battery life and the the amount of time it will stay charged.—Preceding unsigned comment added by 71.98.94.8 (talk) 20:25, 16 January 2008 (UTC)

Do you mean the little flat things that keep the date/time/basic information while you've got the main-battery out/turned off? They must have something as my phone doesn't lose its memory of time when I turn it off/take out the battery and it would need some form of power to keep time (unless it gets the time from the mobile-signal or kinetic energy). ny156uk (talk) 20:32, 16 January 2008 (UTC)

Those little flat things in cell phones are SIM cards, but I'm not quite sure what you, 71.98.94.8, are referring to. Someguy1221 (talk) 20:49, 16 January 2008 (UTC)

Ultracapacitors may also play a roll here, but I'm just speculating.

Atlant (talk) 20:52, 16 January 2008 (UTC)

While memory batteries aren't a myth, they're not strictly necessary for a cell phone, either. Data like settings and contact lists can be (and virtually always are) stored in flash memory, which is non-volatile (that is, it doesn't require power to maintain state). Time information is not suited for such memory, since it's updating continuously, but cell phones draw that information from local towers. It would seem a reasonable compromise to allow a phone to lose time information knowing that it will be automatically regained when a tower signal is next received. — Lomn 20:54, 16 January 2008 (UTC)

Cell phones remember what time it is after turned on without having to connect to a tower for updates, so presumably draw some minimal power for a clock. Some samsung phones, from my personal experience, could actually be programmed to turn themselves back on at a specified time. I never thought to remove the battery and check if the clock was still accurate minutes later, probably worth doing (but not for me, since the battery on this phone is an absolute pain to remove). Someguy1221 (talk) 23:32, 16 January 2008 (UTC)

(No longer the OP's question, but I'll address it anyway) Mostly what you're describing, though (certainly the Samsung wakeup thing) is with the main battery still installed. I was attempting to address why you don't have to manually set your cell phone's clock/contacts if you remove the battery and replace it. — Lomn 15:59, 17 January 2008 (UTC)

Ahhh! Now that's different! Modern cell phones almost all use lithium-ion batteries or lithium-ion polymer batteries. These, like most rechargeable batteries do not want to be deep-cycled; you should top off the charge whenever possible. Only the much-older nickel-cadmium family of batteries needed occasional full discharges to keep working well, allegedly due to the memory effect.

Atlant (talk) 23:35, 16 January 2008 (UTC)

renewable energy street lights

I went to hanauma bay over vacation and I realized that on the street lights in there parking lot there is a little fan that I think powers a little generater and I also think there was a little solorpanel on the top that was only about as big a the top of a normal street light. Iwas wondering how much all of that would cost. And on the plane ride i noticed that the cities are yellowy orange because of the yellowy orange street lights.Are the yellowy orange bulbs more effitiont than the energy effitiont bulbs they are trying to get people to use in there house? thanks --Sivad4991 (talk) 20:25, 16 January 2008 (UTC)

The yellowy-orange lights are sodium vapor lamps and these are currently the most-efficient light sources available. The low-pressure lamps are extremely efficient but monochromatic; the high-pressure kind are less efficient but allow you to see some colors other than sodium yellow. Neither kind gives a good-enough color-rendering index to be acceptable to light home interiors.

Atlant (talk) 20:43, 16 January 2008 (UTC)

The low-pressure sodium lamps are favored by astronomers, because the light pollution they generate is more easily filtered out than that from other types of lamps. Hence, you will often see LPS streetlights in cities and communities near astronomical observatories. -- Coneslayer (talk) 20:46, 16 January 2008 (UTC)

Sodium vapor lamps (the yellow ones) are quite energy-efficient. Our article on the history of street lighting in the United States doesn't directly compare the efficiency of SVLs with CFLs, but notes that CFLs don't last as long and don't perform as well in cold weather. As for the charging assembly, I wonder if the fan might actually be a cooling fan rather than a turbine. — Lomn 20:49, 16 January 2008 (UTC)

Carbon Monoxide resonance forms

According to this site, the leftmost form is the most contributing. Why? Shouldn't the neutral one be the most contributing? I'm thinking that because it is neutral, it is more stable than the other polar forms. 199.76.154.127 (talk) 21:57, 16 January 2008 (UTC)

Neutral does not imply more stable. This can be seen most easily in this case with a molecular orbital diagram. In the case of carbon monoxide, the three P-orbital bonds available are all lower in energy than the lone pairs around either atom. So when looking at the middle resonance structure, the energy of the molecule can be lowered by having oxygen donate one of its lone pairs to a third bond with carbon. Carbon can't donate any as it has already "run out" forming the existing bonding and anti-bonding pairs (although in reality you can't actually tell where they came from, they all just make their way to the lowest orbitals available, and this website might make that clear to you, just search for "carbon monoxide" to jump to its diagram). As a rule that may be easier to understand, carbon's tendency to achieve an octet overpowers oxygen's tendency to not be positive. Actually, even when carbon's octet isn't at issue, having a major resonance structure with a positively charged oxygen atom is typical of many molecules with C-O bonds. Someguy1221 (talk) 23:07, 16 January 2008 (UTC)

Thank you. I will be looking at the pi orbital site, as right now I'm not too familiar with the details of orbitals. But you said something about the octet rule. When figuring out the most stable form of a molecule, does requirement for octet rule always trump everything else, no matter what kind of atoms are involved?199.76.154.127 (talk) 03:07, 17 January 2008 (UTC)

In general chemistry, the only octet-breaking situations you should ever encounter are complex ions, which (hopefully) obey the 18-electron rule, the central atom of some mineral acids, and boron. And as a tip for oxygen and resonance structures, it is usually OK for an oxygen bound to a carbon to carry a positive charge if all octets are satisfied and either A) another oxygen carries a negative charge or B) the overall charge on the molecule is positive (and in CO, of course, as this is the only way to satisfy octet). As a formality, the lewis structures of many boron compounds have only six valence electrons around boron (which is sometimes but not always accurate). In any event, when this is the case you can usually predict (at least, I know of no exceptions) that the compound will bind to lewis bases. Someguy1221 (talk) 05:48, 17 January 2008 (UTC)

Another diatomic molecule notorious for its bonding is nitric oxide, which cannot satisfy the octet rule due to having an odd number of electrons. Also, multivalent elements in period 3 and higher, most notably phosphorus and sulphur, are quite commonly encountered even in simple chemistry. (As with boron, it is often possible to make compounds of these elements conform to the octet rule, using various tricks ranging from formal charges to exotic bond types, but often the simplest approach is just to allow octet expansion for them. The question of which of these models, if any, in fact best describes the actual electron density distribution in different molecules is often subject to ongoing debate in modern chemistry.) —Ilmari Karonen (talk) 20:40, 19 January 2008 (UTC)

Date genus Bubo was first given(for want of a better word)

I wish to know the aproximate date that the genus bubo was first given to an owl, Horned Owl Blacksmith ^talk 23:20, 16 January 2008 (UTC)

The article says 1806 (in the infobox). (EhJJ) 02:03, 17 January 2008 (UTC)