Wikipedia:Reference desk/Archives/Science/2006 July 18

Humanities Science Mathematics Computing/IT Language Miscellaneous Archives

The page you are currently viewing is an archive page. Whilst you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above. This will insure that your question is answered more quickly.

< July 17 Science desk archive July 19 >

Metal: Dissolving and melting.

Let's say you were locked up in a room with a door with a metal key hole, and simply a metal door knob. If your goal was to somehow liquify the metal, what chemical would be a good preferred choice?

Is there a handy-dandy chemical that can liquify the metal when poured on? When attacking metal, 2 things come to mind: dissolving, and burning (to melt it).

Knowing metals are weak against acidic substances, supposedly a chemical with an extremely low pH could dissolve the metal? Knowing human urine is somewhat on the acid side (I think), can that work well? Or is there a particular metal that will dissolve when touched by human urine?

And if you had a red emergency flare, the kind you keep in your car, or a fusee, could you light that up, to the already acidified metal door knob and hope that with a temperature of around 1,500 degrees Celsius you could melt the metal key hole?

Then, once the metal lock is dissolved/acidified/burned/melted, becoming like mercury at room temperature, voila! Just wondering if this particular scenario was a bit on the reality side. NealIRC 18 July 2006.

All of this would seem to depend, as I understand it, what sort of material you are specifically referring to as "metal". --Fastfission 01:42, 18 July 2006 (UTC)

Careful with the terminology here..."melting", "burning", and "dissolving" are three fairly unrelated processes. And Fastfission is right...there are a lot of metals out there with very many properties. Some metals have a very low melting point but are rather hard to dissolve, some are easy to burn but hard to melt (except in the heat of its own flame), some are easy to dissolve but hard to burn or melt, some dissolve in acids but not bases, some dissolve in bases but not acids, some dissolve only in certain acids or bases (regardless of strength), some dissolve only in dilute acids, etc. Sounds like your goal is really just "make the doorknob go away by some means other than just unscrewing it"? DMacks 02:27, 18 July 2006 (UTC)

you would be far better off trying to dissolve/burn/break the door around the lock. Xcomradex 02:31, 18 July 2006 (UTC)

No, you'd be better off breaking the wall next to it. Don't fuck with the doors. --mboverload@ 07:34, 18 July 2006 (UTC)

There was or is a method used in Britain to weld the end of two railway rails together. Some chemical (I forget which; might be magnesium mixed with something else) was packed into a box around the weld, set alight, and the steel rail welded.

Sounds like a type of thermite reaction. DMacks 17:03, 18 July 2006 (UTC)

The thermite process is still used to weld rails in situ. The basic ingredients are aluminium powder and iron(III) oxide. After a high-temperature start - sometimes by using magnesium - the process produces freshly-molten iron, and enough heat to weld the ends of the rails together.--G N Frykman 22:06, 18 July 2006 (UTC)

No, the process does not weld the rails together, but simply pour molten iron into the gap. It cannot be used to melt something that is not inside the chamber. Philc _T^E_C^I 22:16, 18 July 2006 (UTC)

Rims and Oven Cleaner

Would it damage my car rims if I sprayed oven cleaner on them? The type that foams and you wash it off. They are not chrome, they are just regular rims. Thanks

would it damage your repeat posting ability if you used it to clean your keyboard? Xcomradex 03:07, 18 July 2006 (UTC)

Oven cleaner is usually potassium hydroxide I doubt that would damage any metal but I don't know what it would do to rubber. Theresa Knott | Taste the Korn 07:40, 18 July 2006 (UTC)

If the rims have any aluminium in them, then potassium hydroxide will certainly attack them!--G N Frykman 11:26, 18 July 2006 (UTC)

You can always go out and buy a spray bottle of wheel cleaner, which might contain oxalic acid. --Russoc4 15:26, 18 July 2006 (UTC)

Brain Surgery for Bedwetting

I remember listening to a segment on NPR a few months back about how a doctor was successfully using brain surgery to treat bedwetting in children. Apparently, it is a simple procedure, and is justified because of the psychological trauma bedwetting may cause for the child. However, I still couldn't believe it, so I had to look it up online. I couldn't find it on Google, so I just assumed it would take some time for it to appear more prominently online. However, it didn't turn up in a search today. Does anybody else know what I'm talking about, or at least has heard the program on NPR? JianLi 05:28, 18 July 2006 (UTC)

You sure that wasn't a joke, that it was actually NPR? Doctors would never think of risking to operate on the brain for something such as bed wetting. --mboverload@ 07:31, 18 July 2006 (UTC)

You were probably remembering a conversation about a neurosurgeon operating on the spine for persistent bedwetting. [Here] is an ongoing trial. alteripse 10:46, 18 July 2006 (UTC)

YES I've found it! Here. Thanks for your responses. And it seems that you are right, Alterprise! Both links mention the "filum terminale," which is I guess part of the spinal cord. So I guess what I should have said was "neurosurgery" rather than "brain surgery" JianLi 17:30, 18 July 2006 (UTC)

Gas Stove/Ovens and Electricity

I've noticed that my GE XL44 (stove/oven combo unit), guessing 120V, 60Hz, 9 Amps (1080 watts?), and pretty much all others have a fairly high power draw according to the specs sheets. I understand that they need to power the LED clock and timers, and spark to ignite the gas, but does that really require so much power from the electrical grid? Or am I not understanding how and when it uses electricity? Thanks. - MSTCrow 07:04, 18 July 2006 (UTC)

I wonder if they have that gauge just so they'll all conform to the stove outlets that are common in kitchens?--Anchoress 07:14, 18 July 2006 (UTC)

What, there are special gas-stove electrical outlets in kitchens? And common no less. In what country would that be? In the Netherlands gas is the standard (we're sitting atop the biggest gas bubble in the world). But few use electricity and I suppose those that do would just use a normal outlet. The only example of a special outlet I can think of is for electrical razors in bathrooms. But that's because it tends to get wet there. That doesn't apply to kitchens (well, much less anyway).

As to the question, does the oven have an electrical grill? That would require quite a bit of electrical power, I imagine. DirkvdM 07:38, 18 July 2006 (UTC)

Yes there are special outlets for stoves, in the US and Canada. Because the pull is higher.--Anchoress 07:48, 18 July 2006 (UTC)

My stove appears to use a standard 120V 60Hz plug. - MSTCrow 08:26, 18 July 2006 (UTC)

Please note the original question was why it needs much electricity at all and why it has a large power draw. - MSTCrow 08:30, 18 July 2006 (UTC)

This is an educated guess. Perhaps the burners on the top of the stove use spark ignition, which don't use much electricty. But I'll bet the oven burner(s) use a glowing resistance coil, which uses a lot of energy, albeit for a short time. Can you look at the oven burner as you turn on the gas, and see if there's a spark or glowing coil? Bunthorne 14:51, 18 July 2006 (UTC)

The stovetop uses spark ignition for each burner, but I can't tell on the oven, as it's underneath a flat plate with slots on each side. The broiler looks like it could have some sort of coil though? Some sort of assembly beside the front to back broiler burner, at the back, also front to back. I assume a glowing resistance coil is some sort of spark plug like igniter. - MSTCrow 14:58, 18 July 2006 (UTC)

The resistance coil is much like the filament of a light bulb, but much thicker. When you turn on the gas, the main gas jet doesn't come on at once. First, the coil is energized, and a small "pilot" gas jet is turned on. The glowing coil lights the pilot. There's a thermocouple that senses when the pilot turns on. When the pilot is on, the electricity stops flowing through the coil (since it's done its job), and the main gas jet turns on. Bunthorne 15:07, 18 July 2006 (UTC)

BBC 396 2V

Concerning the history of the BBC; GM also built a 396 2V in 1969 ONLY. The intake is a hard to find item. We've used them on oval track ebgines.—Preceding unsigned comment added by 142.165.252.10 (talk • contribs)

BBC stands for lots of things, as does 2V. Please see BBC (disambiguation) then let us know which article you are talking about. Alternatively you can edit the article yourself.--Shantavira 12:28, 18 July 2006 (UTC)

Thank you, unsigned. I've added your comment to the relevant page. --Heron 20:48, 18 July 2006 (UTC)

Moles

Hello all. This is a homeowrk question, but all i need is some help with the second part- a methods, rather than a soloution, would be appreciated.

A sample of 0.013g of Sodium Fluoride.

a)How many moles of sodium fluoride does this represent (Done) b) How many fluoride ions does this represent?

Thanks.

If you have done part (a) successfully, you will have worked out the correct formula of sodium fluoride as NaF. 1 mole of NaF contains Avogadro's Number of fluoride ions. The rest is a very simple calculation!--G N Frykman 11:23, 18 July 2006 (UTC)

Hmm I still dont know what do do :(. A little more information please?

Moles of NaF = mass/molar mass = 0.013/(23+19). Moles of fluoride ions is the same as moles of NaF. Number of fluoride ions = number of moles x Avogadro's number.--G N Frykman 11:38, 18 July 2006 (UTC)

Wow that's right! Ok thank you all for your help.

Little Orange Beetles in Wiesbaden Germany

Can someone please tell me what the little orange beetles in Wiesbaden Germany are? I am baffled. They look like Lady Bugs, but slightly different. The only thing I can find on the net that even resembles them are Colorado Potatoe Beetles. They run around and mate in little bundles. Most common in morning and evening and are found on sidewalks, around park benches, and especially around flower beds under trees and shrubs. I've also seen them gang up on the side of a building in the shade. They just sit there and hardly move around at all unless disturbed. I'm very interested in know what they are, where can I find research material on them, and how are they classified (pest, contributer, protected, etc ...). Please Help me.

Would they happen to look anything like this? I've often seen them clustered around the bases of trees and shrubs in France and Germany, and they look somewhat like the larva of the Colorado Beetle. --Yummifruitbat 18:45, 18 July 2006 (UTC)

Congo Fever or Congo Virus

Why is Congo Virus called the Congo Virus. I know the ebola virus is known after the ebola river, but why? Thanx.

-- --Alleos 17:00, 18 July 2006 (UTC)Alleos.

Congo virus was first isolated from the blood of a febrile patient in the Belgian Congo in 1956. Like many other viruses, it is named after a geographic area where the disease it causes is endemic. - Nunh-huh 17:05, 18 July 2006 (UTC)

Thanx a lot. I'm truly greatful for such a prompt reply :) --Alleos 17:39, 18 July 2006 (UTC) Alleos

DVD Video burning

Hi guys, do you know a good program (preferably a free one) for burning DVD video from .avi files on my computer so that my DVD player can read it and so that I can get as much video as possible onto one disc (meaning slightly lower quality, obviously). I don't know much about burning DVDs (and the DVD article is way too technical for me), so I'd appreciate some help. Thanks :) - ulayiti (talk) 17:52, 18 July 2006 (UTC)

Check here for a listing of guides (whether any of these guides violate copyright law depends on where you are and other circumstances, like if the .avi file you have is legal or not).--droptone 19:48, 18 July 2006 (UTC)

Plant Search

I know that trying to find a plant by its description must be nearly impossible; however, I am really trying to find the name of this plant. It has green oval leaves. It has red 'pods' that look like some type of seeds but they are not soft like berries. They are somewhat hard and look shriveled a bit. Under these, there are little green and yellow circular pods. The stem of the plant is very viney. It has a rigidness to it as well. The stem curves and there are multiple stems coming from the pot. It looks like it is droopy because the stem is somewhat viney. The leaves are smooth and oval until at the very end of the leaf it forms a tip. If anyone can help me out with this, I would be seriously impressed and grateful. Freebytes 20:18, 18 July 2006 (UTC)

Also, I put a picture at www.sipen.com/images/plant.jpg in case you need a visual reference, but it is a really poor quality picture. Freebytes 20:25, 18 July 2006 (UTC)

Where/when was it collected? Climate? Try Vascular Plant Families , James Payne Smith, Jr. , Mad River Press, 1977, or other. Also see some web Tree of Life website, I forget the name, Yahoo around. --GangofOne 00:04, 19 July 2006 (UTC)

It appears to be a type of 'ant plant'.

Judging the most “flammable”

Judging the most “flammable”

Hi there - just a quick question:

What is the most flammable substance?

This of course leads to another question, perhaps the real issue at hand: How does one judge flammability?

My gut feeling would be to say the one with the lowest flashpoint/autoignition temperature, which seems to be in agreement with the Wikipedia article on flammability (Sorry the link looks external, I was having trouble with the internal link feature)

However, what I want to ask is: is one substance more flammable then another? Some sources, including the Wikipedia article, also suggest that when a substance’s flashpoint is below a certain level, it is considerable flammable. This implies that flammability is a fixed property, i.e. something is either flammable or it is not (if its flashpoint is below a certain valve it is, if higher it is not), and we cannot compare flammability.

So what do you people think?

Thank you for your time, I’d be interested to hear your input!

I am reachable via email at (removed)

The most flammable substance is any discussion of PC vs. Mac, or disputably, trying to sell something on a public forum or within newsgroups. Also, any topic on talk.abortion may be considered immensely flammable. Freebytes 20:29, 18 July 2006 (UTC)

It depends really, do you mean burning with oxygen, or can an axidising agent be introduced, or do you mean in air. Either way osmium tetroxide (which has the higest known oxidation state for a transition metal) is an excellent oxidising agent, and mixed with something like methane, or any alkene or alkane would no doubt burn exceptionally well. Philc _T^E_C^I 22:11, 18 July 2006 (UTC)

Well, there's a fine line between "very flammable" and "pyrophoric", the latter meaning the substance spontaneously ignites in air. —Keenan Pepper 04:04, 19 July 2006 (UTC)

International System of Units

Many published articles report hormone concentrations and use units such as micrograms/ml, ng/ml and pg/ml (example: Estrone sulfate and dehydroepiandrosterone sulfate concentrations in normal subjects and men with cirrhosis). I have been told that these are not the best SI units to use. What units would be better? Would something like nmol/L be "better"? If so, why? --JWSchmidt 22:01, 18 July 2006 (UTC)

Why not ask what the person who told you that what s/he had in mind? --GangofOne 23:57, 18 July 2006 (UTC)

It was a reviewer who I cannot contact. --JWSchmidt 01:28, 19 July 2006 (UTC)

Ideally you will get some information from someone with a medical or biology background. In the mean time, people in the physical siences often don't care for derived units that have a prefix in both the numerator and denominator. The expressions mg/L, μg/L, and ng/L would avoid that issue (notice I have changed l to L, which is the standard in the USA but not necessarily elsewhere). --Gerry Ashton 02:57, 19 July 2006 (UTC)

from a chemistry background, i would say nmol/L (nM) would be the standard measure. both mole and litre are SI units. compounds are measrued in moles to avoid problems with molecular weight, eg. for a mixture of say 347.5 ng/L progesterone and 284.4 ng/L androstenedione, it appears at a glance that there is about 20% more progesterone present, however progesterone is heavier, so actually both hormones are at the same concentration, 1 nmol/L. Xcomradex 03:10, 19 July 2006 (UTC)

• I found several websites (example) that say the SI units for concentration are "mole per cubic meter". I have never seen the concentration of a biological molecule expressed in those units. --JWSchmidt 03:33, 19 July 2006 (UTC)

My guess is they want you to use only one prefix, so make the denominator of the unit an un-prefixed SI unit. If this review was for submission to a publication it may have standards on units you can ask them about. DJ Clayworth 17:38, 19 July 2006 (UTC)

mol/m³ are the SI units of concentration according to IUPAC, but they are almost never used since they are so unwieldy, which is pretty much an IUPAC specialty. eg, if IUPAC had its way on everything, benzene would be cyclohex-1,3,5-triene, and other compounds would be even worse. So in practice, IUPAC has conceeded that some things like trivial chemical names (eg. glucose, benzene etc) and non SI derived units (eg. litres) are here to stay. Xcomradex 23:12, 19 July 2006 (UTC)

architectural working drawings

i need to produce a complete set of working drawing for a semi-detached building and i need a format to follow. thank you. Imaobong

When a bird moults, is it painful?

My hyacinth macaw is going through his moult at the moment and he seems really cranky and irritable. When he loses one of his long tail or wing feathers, he shakes the appendage as though it was really sore afterwards - those feathers have really deep roots. He's also got his 'spikes' coming through. Having those push up through your skin doesn't look like much fun. He hates to be stroked when he's like this and is generally somber and moody. I can tell he's really itchy (he can't stop scratting, preening and rubbing himself) - but does anyone know if he'll actually be in physical pain? Poor little (well, big and blue really) guy.

He is doing all that stuff to speed up the moulting process, I don't think he is in pain. See moulting — The Mac Davis] ⌇☢ ญƛ. 23:24, 18 July 2006 (UTC)

He's a smart bird. If you own a pet bird, on occasion you have to pull a broken 'blood feather' out from the root yourself (with tweezers/pliers) because basically the blood gushes out like through a straw and can kill them pretty quickly. I got this parrot and the first time he caught his wing on something and snapped a blood feather, he looked down at it, then swiftly yanked it himself and gave me one of those 'what?' looks. :)

I think it's only human-raised birds that don't know how to do that. My birds certainly know how to remove leaking blood feathers. I guess they wouldn't have survived so long in the wild if they didn't. I've only ever had to do it a couple of times myself. The Pin feathers are therefore sensitive, and some pet birds do not enjoy being handled while moulting for this reason line in the above article sorta answers your first quesion too. I'd love to own a hyacinth macaw. It'd be one of my dream pets. --Kurt Shaped Box 23:46, 18 July 2006 (UTC)

Oh yeah, when the pin/blood feathers start growing longer and the blood recedes down, try gently cracking the shafts between thumb and forefinger and picking away at the keratin coating. If your bird lets you do that, it'll help the new feather to unroll, relieve a lot of itching and he'll love you for it. It's a good bonding excercise. To him, you're just a big, funny-looking parrot and parrots expect (if not *demand*) other parrots to help them out with this, especially on the head and the back areas. My parrot likes to groom my beard and long hair when I'm doing this. --Kurt Shaped Box 23:55, 18 July 2006 (UTC)

I've noticed my Indian ringneck parakeet is more somber on some days when he is molting. He is normally quite full of himself. I think at least some psittacines feel something, whether from physical discomfort or hormones. I could not say about other types of birds. --Ginkgo100 ^{talk · contribs · e@} 04:21, 20 July 2006 (UTC)