Wikipedia:Reference desk/Archives/Science/2007 October 10

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[edit] October 10

[edit] 9th cartilage of the larynx

I am trying to complete my notes on the larynx. I was double checking between my notes from a lecture to that of the article here on wikipedia. I seemed to have never completed my notes on the cartilages. I've got down for the cartilages the cricoid, thyroid, cuneiforms, corniculates, and arytenoids. The cricoid and thyroid are single (unpaired) cartilages while the cuneiforms, corniculates and arytenoids are paired. I counted 8 cartilages all together. What is the 9th cartilage of the larynx? Thanks --Agester 01:01, 10 October 2007 (UTC)

Epiglottis (single). --Milkbreath 01:50, 10 October 2007 (UTC)

Here is the relevant page from Henry Gray's Anatomy http://www.bartleby.com/107/236.htm Richard Avery 08:50, 10 October 2007 (UTC)

[edit] Are we Monkeys?

We have evolved from apes and a ape is a tailess monkey, so therefore what kind of animals are we monkeys?

We are our own species. You could always take a crack at Human evolution. This article includes a nice chart diagraming our split from what became chimps. Someguy1221 03:05, 10 October 2007 (UTC)
We are apes, not monkeys, and apes are not simply "tailless monkeys," as you suggest. Apes are, like, smarter and better.--The Fat Man Who Never Came Back 03:24, 10 October 2007 (UTC)
No - we aren't monkeys. Neither are chimps, gorillas, bonobos, orangutans, etc. There are three kinds of Simians/Primates. The three types are: Old World monkeys, New World monkeys and Apes. Humans are apes - so we are not monkeys - but (like the monkeys) we are all primates. SteveBaker 04:04, 10 October 2007 (UTC)
what about lemurs? they're not monkeys or apes, are they? --The Fat Man Who Never Came Back 04:07, 10 October 2007 (UTC)
Lemurs are prosimians. From Primate: The Primates order is divided informally into three main groupings: prosimians, monkeys of the New World, and monkeys and apes of the Old World. — Scientizzle 04:23, 10 October 2007 (UTC)

We also didn't evolve from any current species. Rather every species have evolved through different paths and we have a common ancestor. --DHeyward 06:16, 10 October 2007 (UTC)

That's true - but we are still evolved from creatures who we'd call "apes" - just not any specific present day ape. SteveBaker 13:35, 10 October 2007 (UTC)

Jared Diamond's book The Third Chimpanzee takes its title from the statement that, if you look at it impartially, you'll find that the genus Homo is not really sufficiently distinct to be considered as separate from the genus Pan. The latter genus includes the common chimpanzee and the bonobo or pygmy chimpanzee, so the idea is that Homo sapiens should really be Pan sapiens, a third type of chimpanzee. --Anonymous ___ sapiens, 22:14 UTC, October 10, 2007.

Indeed, while I've never read Mr. Diamond's book, cladistically a Homo/Pan distinction is completely arbitrary and anthropocentric. --Cody Pope 05:00, 11 October 2007 (UTC)
There might be more sympathy for this view if they proposed 'Homo troglodytes' and 'Homo paniscus' for the chimpanzees rather than using 'Pan sapiens' for humans.
Wasn't the common chimp formerly called Homo silvaticus? —Tamfang 19:25, 14 October 2007 (UTC)
I don't know, but above I was misremembering what Diamond said about the name for the single genus. He actually said that since the name Homo was older as a genus name than Pan, nomenclature conventions would require Homo to be extended to chimps rather than Pan to humans, if they were officially merged. Sorry about the error. --Anon, 06:08 UTC, October 15, 2007.
I'm very fond of the fact that there is more genetic difference between a male human and a female human than there is between a male human and a male chimpanzee or between a female human and a female chimpanzee. It turns out that (biologically speaking) this is really no surprise - but it explains a lot about 'the human condition'. SteveBaker 05:10, 12 October 2007 (UTC)

[edit] Source of fruit flies

I looked at the article on fruit flies, but it did not answer my main question. Where do all those fruit flies come from when you open a banana and leave it uneaten over night. The flies only appear once the banana is opened, so are the eggs inside the peel? What triggers the hatching? How do the bananas become impregnated? I have difficulty imagining a little fruit fly with an ovipositor longer than its body length inserting eggs beneath the peel. How long can the eggs survive before hatching? Any answers will be appreciated.

See Spontaneous generation.--The Fat Man Who Never Came Back 03:41, 10 October 2007 (UTC)
Yep! That's what my momma told me too. - hydnjo talk 03:54, 10 October 2007 (UTC)

Why don't you do a science experiment? Buy a banana. "open a banana". Place banana inside a glass jar. Seal the glass jar completely. Leave the banana overnight. 202.168.50.40 03:50, 10 October 2007 (UTC)

Maybe you just have fruit flies wherever you're opening them. I can attest I've never found a fruit fly on fruit in my house. Someguy1221 03:55, 10 October 2007 (UTC)
Well, you have a mommy fruitfly and a daddy fruitfly who love each other very much...er...sorry, wrong answer. I don't think the egg has to be laid all the way in the core of the banana - if the larvae are mobile, they can work their way into the middle of the banana from just under the skin. The eggs develop in between 7 and 50 days depending on the temperature. SteveBaker 03:57, 10 October 2007 (UTC)
A fruit fly researcher I know has just informed me that the little guys are unlikely to lay eggs on fruit that's not even ripe yet. Someguy1221 05:01, 10 October 2007 (UTC)
That makes it very unlikely that these flies were inside the banana all that time then. If the fruit has to be ripe when the eggs are laid - and they take a minimum of 7 days to mature into flies. So the banana would have to be (at a minimum) 7 days past being ripe. They must have been in the house all along and were simply attracted to a handy opened banana. SteveBaker 13:33, 10 October 2007 (UTC)
It's not just bananas, we have resident fruit flies in our house that seem to replace themselves over several months, but never exceeding 2 or 3 that fly around entering and leaving one's field of vision in a cursedly annoying way. They definitely prefer grapes and apples, sometimes we don't have bananas. I assumed they had flown in from the garden where we have zillions in our compost bin. Richard Avery 08:45, 10 October 2007 (UTC)
If you are in a climate where fruit flies thrive, you need to keep fruit shut away in a refrigerator (low temperatures dramatically increase the time it takes their eggs to hatch) and to dispose of leftovers in a garbage disposal unit - or at least remove your kitchen trashbags regularly. Any piece of fruit left lying around for more than (maybe) 7 days at room temperature is going to be a source of new fruit flies. SteveBaker 14:31, 10 October 2007 (UTC)
Drosophila melanogaster love bananas (specifically the yeast) and some variety of it is likely what you are talking about. This is one of the reasons they became model organisms for genetics—they are super easy to breed, you just leave out a bunch of bananas for awhile and they show up in spades. Eventually the Morgan group found a cheaper form of food than bananas for them (some sort of yeast agar or something like that). I didn't even realize that those little gnat like guys were the fruit flies of fame and fortune for a long time. (A great book on the subject of the flies and genetics: Lords of the Fly by Robert E. Kohler) --24.147.86.187 22:26, 10 October 2007 (UTC)

[edit] need info on milk

Sir

what does butter fat mean?

How it is useful for growing kids?

How a pack of milk is special due to butter fat content?

Why do pepole prefer milk, is it because of taste,practise or anything else.

Regards

Sathish

Dear Mr. Sathish, You can go through the article Butterfat. I am not sure if I can go into any details on the topic myself but my obvious suggestion would be for you to check Milk, Fat (importance for living organisms), and the above link Butterfat. Hopefully, as you read the above articles, someone will come and give definite answers to your questions. Regards, Kushal --KushalClick me! write to me 05:16, 10 October 2007 (UTC)

[edit] Identify this spider

Hello, I'm no spider expert. Could somebody identify this one? Image:Spider-2007-10-09.png. Thanks! Sancho 07:20, 10 October 2007 (UTC)

Tegenaria domestica better picture in the German article (marks on the back)--Stone 08:31, 10 October 2007 (UTC)
Tegenaria gigantea, Tegenaria agrestis have different size, but look similar, so you have to decide how big the spider is. Tegenaria agrestis (Hobo spider) is dangerous according to the article.--Stone 08:37, 10 October 2007 (UTC)
Its body was about 1cm, with a leg span of about 3 cm. Sancho 15:40, 10 October 2007 (UTC)

[edit] Are electrons gaining weight?

I remember being told in science classes, when I was a kid, that electrons didn't have any mass. I've just skimmed over the electron article and found that they do have mass. Did something change in the last 15-20 years in our understanding of electrons or am I remembering incorrectly? Dismas|(talk) 09:15, 10 October 2007 (UTC)

I don't think this is a recent development, but you may not be remembering wrong either. Quite often at school level, simplifications are made, or approximations are made for the sake of doing calculations. The electron weighs about 2000 times less than the proton, so it is often appropriate to simply ignore the electron mass as it is so much less. You may also be interested in neutrinos, long thought to be massless, but recently their tiny masses have been detected. Cyta 11:31, 10 October 2007 (UTC)
It's mass is around 1/1823. You were likely told in high school that it had no mass because its mass is so small as to be neglible and can usually be ignored. Backsigns 12:41, 10 October 2007 (UTC)
I was taught that electrons had 1/1823rd of the mass of a proton. That was in high school ~40 years ago. So either they were teaching you an untruth or an approximation that's only relevent when calculating atomic masses and such...or perhaps your memory has failed you. Maybe you are remembering photons or neutrinos? Photons are often described as having zero mass (technically, they have zero 'rest mass') - and neutrino's were probably still thought to have no mass back 15-20 years ago although now we know they do have a very tiny mass. In 1963, John Updike wrote:
Neutrinos - they are very small.
They have no charge and have no mass
And do not interact at all.
...which is now known to be untrue. (There is more to the poem here). —Preceding unsigned comment added by SteveBaker (talk • contribs) 13:28, 10 October 2007 (UTC)
Lest there be any uncertainty, this is not a recent development: on discovering the electron, J. J. Thomson immediately measured its mass/charge ratio and found it to be small but nonzero. Algebraist 19:31, 10 October 2007 (UTC)
You may be remembering the first half of the full name of the most common neutrino, which is the "electron neutrino." This particle was thought to have no mass and is now thought to have a really, really small mass -- much less than the mass of the electron. -Arch dude 20:45, 10 October 2007 (UTC)
So while "they have no mass" could be viewed as a reflection of the slightly wrong understanding of the time, the "do not interact at all" part had to be understood to be not quite correct even then. If they didn't interact at all, then they also could not have been created by any interaction (by the CPT theorem or something). But both assertions are well within poetic license even today. --Trovatore 20:56, 10 October 2007 (UTC)
It could also be that, since the electrons are ~1/1800 the mass of the neutron or proton, they have zero mass number, while neutrons and protons have a mass that's a bit more than one atomic mass unit, are considered to have a mass number of 1. Confusing Manifestation 01:23, 11 October 2007 (UTC)

[edit] solanine poison

Amit3405 09:54, 10 October 2007 (UTC)amit3405 what is the postmortem findings in solanine poison in human.

Check out Glycoalkaloid. Alas, the link that would probably answer your question is currently broken. --Mdwyer 18:47, 10 October 2007 (UTC)
I don't understand any of it but Solanine has a section called Solanine poisoning. Could you see if there is any material (or external references and links) there that you could use? --KushalClick me! write to me 20:44, 10 October 2007 (UTC)

[edit] bovine serum albumin blocking

I don't understand the use of bovine serum albumin in immunostaining. --Seans Potato Business 10:26, 10 October 2007 (UTC)

It is the same idea as discussed at Western blot#Blocking. Cells and tissues will often "non-specifically" bind proteins. BSA is one of several relatively inexpensive proteins that is commonly used to block non-specific protein binding sites in samples. --JWSchmidt 14:01, 10 October 2007 (UTC)
I see. I was looking at it backwards. Do you know any examples of components that bind non-specifically? It's not important, I'm just wondering... --Seans Potato Business 16:45, 10 October 2007 (UTC)
One possibility that comes to mind is that "heat shock proteins" or chaperonins might bind some partially denatured antibodies during immunostaining. I doubt if anyone has ever tried to study this; "non-specific protein binding" sorta implies that it would be hard to figure out what is going on because the molecular interactions would be a complex jumble. --JWSchmidt 17:54, 10 October 2007 (UTC)

[edit] Neutrons and protons in the nucleus

I just read Neutronium and whilst it makes sense (no force to hold the neutrons together?) it made me wonder what exactly holds the protons and neutrons together in the nucleus of an atom. Are the neutrons simply trapped by the protons? Backsigns 12:38, 10 October 2007 (UTC)

It's something called the nuclear force, that only operates on very small ranges. Normally it holds them pretty tight but if you can make the nucleus super big then its constituent parts will fall outside of its range and the electromagnetic force will kick in (forcing the two positive nuclei to repel rapidly from one another) as is seen in nuclear fission. In nuclear fusion the whole trick is getting positive nuclei close enough together so that the nuclear force will kick in over the electromagnetic force. --24.147.86.187 12:47, 10 October 2007 (UTC)
Heh, this should have been obvious to me. Thanks a lot, that article is very helpful :) Backsigns 12:49, 10 October 2007 (UTC)
And for the real-life neutronium that may exist in neutron stars (see the article), the answer is that gravity holds it together. --Anon, 22:19 UTC, October 10, 2007.

[edit] British fetus embryo standards

According to a science story released today at ScienceDaily [1] from UPI, and cited to the Daily Mail, the British health minister, Dawn Primarolo, has given permission for British scientists to create human-animal hybrid fetuses embryos (pony boy? goose girl?) but the "chimaeras" will be "destroyed within 14 days of creation and will not be allowed to develop into living beings." My question is, on what day of fetus embryo development does a hybrid fetus embryo, or even a purely human fetus embryo "develop into a living being" (edit) per British laws and standards, and what basis was used for deciding whether the fetus embryo was "living?" Or is it considered "living" from day one but not yet a "being?" How many days could such a hybrid fetus embryo survive with today's technology in vitro, or could it conceivably be implanted into a human or animal uterus and develop to term? Did the press release as published in ScienceDaily misstate the government pronouncement? Edison 13:46, 10 October 2007 (UTC)

It makes little sense to use the term "fetus" in this context. A human embryo less than 14 days old is basically a collection of cells. These experiments are designed to use chimeric embryos as a way to isolate human stem cells, not a chimeric fetus. --JWSchmidt 14:08, 10 October 2007 (UTC)
Technically, this would be an embryo - not a fetus (the arbitarily chosen time when the terminology switches is 8 weeks after fertilisation). Our article on Prenatal development has a week-by-week account of what forms and when - but basically, 2 weeks after fertilisation, there is no heart or digestive systems, no arms or legs, no brain or spinal cord - the embryo is still a blob of cells just a couple of millimeters across with no obvious 'head' or 'tail'. There is no definite time when you can say the embryo is a "living being" - it's been "living" since day one (actually, before day one - in some senses) - and the definition of a "being" is a judgement call - so pick whatever time suits your personal biasses. The embryo implants into the uterus at day five after fertilisation - whilst I'm certainly no expert, I presume that two weeks is far too late to implant it into a live animal/human. SteveBaker 14:17, 10 October 2007 (UTC)

[edit] What would a nuke do to a Tornado?

If a nuke were detonated in a tornado, what would it do to it? Ignore the effects of the nuke on the surrounding enviroment, structures. What would it do to the tornado itself? 64.236.121.129 15:31, 10 October 2007 (UTC)

I don't know what would happen, but I just wanted to say that this question is hilarious in a really awesome way. I hope someone knows the answer. Beekone 15:51, 10 October 2007 (UTC)
I would expect the heat from the detonation to immediately evaporate any of the water droplets that had made the tornado visible. Next, the blast pressure caused by the explosion would dominate the pressures that cause the tornado to form. The rotation that was present before the detonation would be masked as only a very small component of the expanding blast wave and blast winds that reach speeds of several hundreds of miles per hour. Sancho 16:10, 10 October 2007 (UTC)
I get this mental image of Bush saving us from the threat of the tornado using this miracle cure-all. Very entertaining post. Beekone 16:31, 10 October 2007 (UTC)
With a big enough nuke, the shock wave should be able to disperse the cumulonimbus cloud that was powering the tornado (just look at some of the film of old nuke tests - the bomb literally rips a hole in the cloud cover). Of course, if by some magic, the bomb failed to stop the tornado, then you'd have a swirling column of radioactive dust cutting through the countryside - not nice! Laïka 19:30, 10 October 2007 (UTC)
Would an airplane pilot dare to fly into a tornado to do this? – b_jonas 06:40, 11 October 2007 (UTC)
Hurricane researchers do that 'all the time'. A hurricane is pretty destructive to something standing on land because it is standing still. An airplane can 'go with the flow'. Still not without risk, though. And of course, a tornado is not a hurricane. It's much smaller in size, so you can get closer to its centre. Then again, you could also use a rocket. Problem solved, yes? DirkvdM 09:18, 11 October 2007 (UTC)
Would the blast wave not disrupt the cloud cover, thus stopping the tornado? Also, what's preventing us from lobbing a couple of high explosive bombs set for airburst into a hurricane to disrupt the cloud cover? We could get a plane, drop a few at very high altitude, mess with the clouds and presto, no hurricane. Of course, we have to take into account that accuracy will be poor since these bombs are flying through 100mph winds and such.
Note, of course, that a nuclear bomb would be of no effect on something as large and diffuse as a hurricane. --24.147.86.187 13:32, 11 October 2007 (UTC)
That's what I would have thought too, but Hurricane#mechanics says that the energy released by a Hurricane is equivalent to "exploding a 10-megaton nuclear bomb every 20 minutes". So it's sort of in the same order of magnitude. At least for 20 minutes. :) DirkvdM 18:15, 11 October 2007 (UTC)
I wouldn't want to fly an airplane into a tornado. Hurricanes are pretty safe -- they're large, predictable structures, without much in the way of sudden wind shifts. Tornadoes are much more compact -- a small plane might find itself with one wing in the strong updraft of the center, the fuselage in a 200 mile-per-hour headwind, and the other wing in the relatively still air outside the tornado. --Carnildo 21:53, 11 October 2007 (UTC)
So, There is a difference between flying in a hurricane and above a hurricane isn't there?
Mrdeath5493 06:03, 12 October 2007 (UTC)

[edit] What does blood color mean

If a non-human primate has brighter-red (rather than darker red) blood than normal, what might be inferred? --Seans Potato Business 16:57, 10 October 2007 (UTC)

Nobility if your blood is blue, right? Beekone 17:07, 10 October 2007 (UTC)
It could be a result of a couple of things, one is that it could indicate a higher level of blood oxygenation (specifically the ratio of deoxyhemoglobin to oxyhemoglobin). Oxygenated blood is a bright red in color, deoxygenated blood is a darker shade of red, which is why venous blood is darker than arterial blood. Of course, there could be other explanations, as some animals have higher levels of beta-carotene in their plasma which may result in changes in the colour of their blood. Rockpocket 17:35, 10 October 2007 (UTC)
Perhaps the blood has been infused with carbon monoxide which will make the colour more bright red. Graeme Bartlett 20:57, 10 October 2007 (UTC)
I believe blood is sort of a maroon color when de-oxygenated , only turning bright red when exposed to oxygen. —Preceding unsigned comment added by 88.110.114.11 (talk) 23:59, 10 October 2007 (UTC)

[edit] what is water phase?

The water phase was adjusted to 300 mM NaCl and diluted with 2.5 volumes of ice-cold 100% ethanol. - this is a line from a methods section in an article; when they're talk about the 'water phase' do they mean the component that was water, among their mixture that included phenol: chloroform:isoamyl alcohol (16:16:1)? Is this immiscible with water or something? --Seans Potato Business 16:53, 10 October 2007 (UTC)

Indeed. When you add phenol: chloroform : isoamyl alcohol to a solution containing water, you will get two phases: an aqueous phase (usually on top) and an organic phase. From the protocol you quote it sounds like someone wants to separate DNA, which will be in solution in the aqueous phase, from protein. You can precipitate the DNA by adding cold ethanol to to aqueous phase to form a floccule (which is one of my favorite words!). See Phenol-chloroform extraction, followed by ethanol precipitation, for more details. Rockpocket 17:23, 10 October 2007 (UTC)

[edit] White Tailed Eagle

Can someone tell me what predators the White tailed Eagle has? —Preceding unsigned comment added by 64.193.145.145 (talk) 17:17, 10 October 2007 (UTC)

White-tailed Eagle#Near-extinction and recovery in Europe "White-tailed Eagles are alpha predators"
The eggs might be subject to 'predation'87.102.79.56 17:54, 10 October 2007 (UTC)
We humans - probably. There are people out there with guns who get unduly excited about this kind of thing. SteveBaker 16:13, 11 October 2007 (UTC)

[edit] Image of Sun going around the earth

I don't know if it makes any sense but I wonder (roughly) what shape would the motion of the sun make if we considered the motion of the earth and the sun keeping the earth at the center of the paper and the sun moving round it.

Please delete this post if you know what I mean AND/OR think I am talking nonsense. Thank you. --KushalClick me! write to me 20:41, 10 October 2007 (UTC)

Is this what you are on about? --80.229.152.246 21:03, 10 October 2007 (UTC)
If your coordinate system is tied to the centre of the earth and fixed stars it will be an ellipse for the shape of the sun's orbit. If the earth has coordinates fixed in the surface the sun will appear to move in a circle. Graeme Bartlett 21:02, 10 October 2007 (UTC)
For an animation of the geocentric model, there's a movie here. - Nunh-huh 21:18, 10 October 2007 (UTC)
See Tychonian system for a geocentric model that is mostly compatible with Copernican observations and is pretty much just changing the frame of reference from the sun to the earth (though the motion of the stars is not correctly accounted for in that case, but with the instruments at the time you couldn't detect that). --24.147.86.187 22:20, 10 October 2007 (UTC)
We even have an article on analemma. 85.127.20.138 22:39, 10 October 2007 (UTC)
The path of the sun around the earth would be exactly the same as the path of the earth around the sun - which to a first approximation is an ellipse (if you look very carefully, the ellipse has wobbles in it due to the mass of the moon orbiting the earth and other still smaller influences from the other planets - but the sun would appear to have those exact same wobbles if you put the earth at the center - but since the sun isn't influenced much by the feeble gravity of the moon, this is one clue that treating the earth as the center of the solar system makes very little sense). SteveBaker 16:12, 11 October 2007 (UTC)

A very sincere thanks to all of you. The Quicktime Movie closely matches what I wanted. So the path that the sun would have around the earth would be just like the path the earth has around the sun? I am still unable to picture this in my head.

Any more suggestions, links, wikilinks, etc would be very appreciated. --KushalClick me! write to me 03:17, 12 October 2007 (UTC)

The Sun's position-vector relative to Earth is the opposite of the Earth's position-vector relative to the Sun, so the curve is the same curve rotated a half-turn. Does that help? —Tamfang 19:34, 14 October 2007 (UTC)

[edit] 2N in 2N HCl

What does the "2N" mean in "2N HCl"? --Seans Potato Business 21:46, 10 October 2007 (UTC)

Probably "2 normal". "Normal" HCl contains one equivalent (which in this case equals one mol) of HCl per liter (of water, presumably). 2N HCl is twice as concentrated as that. --Trovatore 21:48, 10 October 2007 (UTC)
Yes it does mean normality, which is related to concentration and molarity. But the conversion of normality to molarity varies from compound to compound. For HCl, which dissociates 1 mole of hydrogens (protons) per mole HCl, a 1 normal solution would be 1 molar. For sulfuric acid, which dissociates 2 moles of hydrogen per mole of acid, a 1 normal solution would be 0.5 molar. I think. See Molality#Normality, although it's not exactly too clear. I remember our analytical chemistry professor saying this is on his list of the most confusing and possibly pointless things chemists have ever done. --Bennybp 21:57, 10 October 2007 (UTC)
Bennybp is correct. And I agree it's somewhat pointless. I imagine it was intended to be less confusing; instead it is more. -- Flyguy649 talk contribs 22:23, 10 October 2007 (UTC)
Only use I've seen for normality is with standardized solutions when you really care about the concentratation. "I know it's 2M HCl because I did an acid/base titration"—no, you know it has 2 moles of H+, so you can only really talk about that ion and then explain that in terms of how much HCl would make it. So yeah, confusing and pretty damn useless in most contexts. DMacks 02:18, 11 October 2007 (UTC)
As long as you understand the definition of normality, it is about as useful as any other way to measure concentration.Mrdeath5493 05:59, 12 October 2007 (UTC)
No, it isn't.
See, for example, the explicit prohibition of its use in NIST Special Publication 811, Guide for the Use of the International System of Units, section 8.6.5:[2]
2. The term normality and the symbol N should no longer be used because they are obsolete. One should avoid writing, for example, "a 0.5 N solution of H2SO4" and write instead "a solution having an amount-of-substance concentration of c[(1/2)H2SO4] = 0.5 mol/dm³" (or 0.5 kmol/m³ or 0.5 mol/L since 1 mol/dm³ = 1 kmol/m³ = 1 mol/L).
Gene Nygaard 13:42, 12 October 2007 (UTC)
But 0.5N H2SO4 is actually 0.25 mol/L, right? --Seans Potato Business 22:00, 13 October 2007 (UTC)
Yes. The "normality" of an acid like sulfuric acid can be thought of as the concentration (in mol/L) of the protons in the solution. Since sulfuric acid gives 2 protons per molecule, the concentration of H2SO4 (although it doesn't exist that way in solution) would be 1/2 the normality. It's hard for me to wrap my head around that like from the NIST, too. Somtimes, I think they try too hard (molarity is obsolete?????). --Bennybp 23:33, 13 October 2007 (UTC)