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Copied from Talk:Tungsten#At_what_temperature_does_tungsten_burn:
"Tungsten metal forms a protective oxide when exposed to air but can be oxidized at high temperature."
From what I read in a research paper a while ago (in which they heat tungsten by induction in still air), the oxide has a lower melting point than the tungsten metal, which allows it to be ablated away by a hot enough flame, and the layers of tungsten underneath oxidized and ablated away and so on. But what temperature, exactly?
Which of these forms under a hot flame? All of them? What's the minimum temperature flame required to turn a piece of tungsten into smoke (rather than just heat it up)? Would a pure oxygen atmosphere make a difference? — Omegatron ( talk) 00:11, 18 April 2008 (UTC)
That doesn't really answer the questions. Let's restate them:
Icek states that nitrogen is not used in tungsten filament lightbulbs, and implies that carbon filaments could be run at a higher temperature than tungsten,but our article Incandescent light bulb says it nitrogen is used in tungsten bulbs, sometimes with other gases. Rather than burning up "instantly" tungsten filaments sometimes last a few second exposed to the atmosphere. And some smaller lightbulbs still have vacuum around the filament rather than a protective gas. Some early tungsten bulbs used nitrogen alone. An old (1917) source (available online) [1] says carbon filaments were operated at 1600 celsius and tungsten at a higher temperature of 2000 celsius. Carbon filaments were too short-lived (though higher efficiency) if operated near their sublimation temperature. This source also states that nitrogen was used as a fill gas for tungsten filament bulbs. A newer book (1994) says again [2] that carbon filaments are only operated up to 1750 C while tungsten filaments are operated at 2400 to 2750 C with fill gas of argon or nitrogen. Edison ( talk) 23:48, 18 April 2008 (UTC)
Regarding Omegatron's question, this link does unfortunately not answer it but it says that when light bulbs are broken it's mainly tungsten(VI) oxide. This document which is not freely available should answer the question. Icek ( talk) 03:08, 19 April 2008 (UTC)
I read that in a previous thread, but didn't want to hijack it. Imagine Reason ( talk) 01:12, 18 April 2008 (UTC)
The very sad historical fact is that per United States Radium Corporation women were reportedly employed to paint "glow in the dark" dials and had to lick the brushes to shape them, thereby ingesting radioactive pigment which caused cancer. Edison ( talk) 05:05, 18 April 2008 (UTC)
What are the web sites of the largest professional societies concerning industrial hygiene? 75.61.111.185 ( talk) 08:48, 18 April 2008 (UTC)
hi!!!!! I would like to ask a question about human powered vehicles. what is the role of "Aerodynamic lift" in human powered vehicles -land?? and how is it countered for the same vehicles??
Please reply as soon as possible Thanking you
Does the US military currently have any plans to adopt NOTAR technology? -- AtTheAbyss ( talk) 13:03, 18 April 2008 (UTC)
I didn't have any imagineary friends when I was little, but I had some imaginary "experiences". For example, i clearly remember rays of bright colors shooting across the night sky, and two goats singing (in human voice) while grazing. There were other, even sillier, incidents too. I believed in these and remembered them just like actual memories until I was grown up enough to realize they couldn't possibly have happened actually. Is there any name (or an article) for such a phenomenon? Thanks. 125.21.165.158 ( talk) 16:01, 18 April 2008 (UTC)
I have noticed that many swimming pool chemical products give two sets of different dosage instructions: one for 'stabilsed' pools, the other for 'non-stabilsed' pools. What is the difference, and how do I know which category my own pool fits into ? Thank you-- 196.207.47.60 ( talk) 16:36, 18 April 2008 (UTC)
There seem to be so many questions about oil recently, and they got me thinking. Will it be possible to chemically syntesise oil? If it will, could it ever be financially viable to do so? Could we improve on oil by making it less polluting or something? If we can't do any of these things, why not? We can make diamonds, right? Michael Clarke, Esq. ( talk) 16:52, 18 April 2008 (UTC)
Yes, we can make diamonds ( synthetic diamond), and yes, we can synthesize oil. It's actually not terribly difficult at all (see synthetic oil, but keep in mind those methods start with other fossil fuels. There are other synthetic methods that can start with plant matter, see Fischer-Tropsch process). As mentioned repeatedly, the main problem is that it costs energy (which should not be surprising to anyone with a basic understanding of chemistry, since oil is usually used as a source of chemical energy). And so it will never ever be energetically viable to synthesize oil, as you'd need to drive the process with an amount of energy greater than you could retrieve by burning the oil you ended up making. But there are other uses of oil, and very important ones. Virtually the entire petrochemical industry relies on oil and other fossil fuels. As such fuels become scarce, it will become financially viable to synthesize such chemicals from plants, and there are some people already doing just that. And there is certainly the biofuel movement to create renewable fuels, not that it would actually be energetically efficient at all, and the current biofuels compete with land for food crops to create even more issues. Someguy1221 ( talk) 17:59, 18 April 2008 (UTC)
There are uses for synthesizing a liquid form of energy, however, if that allows for a greater power-to-weight ratio than the original form. For example, let's say you have electricity from solar, wind, hydro, or nuclear sources. You can create cars that run on electricity, but not planes, as the batteries weigh too much and store too little energy to be useful there. So, using the electricity to synthesize some form of liquid fuel may make sense. Also, since the existing car fleet can't easily be switched to electricity, the synthetic fuel may make sense during the transition period for cars, as well. StuRat ( talk) 19:20, 18 April 2008 (UTC)
There is much more to automotive fuel than the fact that ancient solar energy is stored in it and that it provides net energy greater than the energy needed to extract refine and transport it to the filling station. Liquid hydrocarbon fuel is presently a far denser form of energy, both by space and by weight, than other forms of portable energy which could be used to power cars such as batteries. There should be a market for synfuel even if it takes more energy to produce than it provides to the car. The input energy used in the synthesis could be something green like a solar array on the roof of a residence or something less green like a breeder reactor. The end result should be a source of energy that will power a car at highway speeds as far as a tank of gas presently does. After over 100 years of electric cars, batteries still suck at energy density compared to liquid fuel. Some process which converts plant material to auto fuel, or which provides hydrogen fuel, even with a greater energy input than the energy the fuel ultimately delivers to the car, would be of interest. We are expected to arrive at the year when the maximum amount of petroleum is extracted from the ground , and worldwide demand is constantly growing, which will steadily drive up the cost of petroleum as old oilfields are re-worked and less promising fields are exploited in more expensive, sometimes more polluting, and sometimes more water-wasting methods. Edison ( talk) 23:15, 18 April 2008 (UTC)
is there any upper limit to (measure) temperature? plz answer —Preceding unsigned comment added by Harshkothari ( talk • contribs) 19:47, 18 April 2008
No SpinningSpark 21:22, 18 April 2008 (UTC)
Science desk | ||
---|---|---|
< April 17 | << Mar | April | May >> | April 19 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
Copied from Talk:Tungsten#At_what_temperature_does_tungsten_burn:
"Tungsten metal forms a protective oxide when exposed to air but can be oxidized at high temperature."
From what I read in a research paper a while ago (in which they heat tungsten by induction in still air), the oxide has a lower melting point than the tungsten metal, which allows it to be ablated away by a hot enough flame, and the layers of tungsten underneath oxidized and ablated away and so on. But what temperature, exactly?
Which of these forms under a hot flame? All of them? What's the minimum temperature flame required to turn a piece of tungsten into smoke (rather than just heat it up)? Would a pure oxygen atmosphere make a difference? — Omegatron ( talk) 00:11, 18 April 2008 (UTC)
That doesn't really answer the questions. Let's restate them:
Icek states that nitrogen is not used in tungsten filament lightbulbs, and implies that carbon filaments could be run at a higher temperature than tungsten,but our article Incandescent light bulb says it nitrogen is used in tungsten bulbs, sometimes with other gases. Rather than burning up "instantly" tungsten filaments sometimes last a few second exposed to the atmosphere. And some smaller lightbulbs still have vacuum around the filament rather than a protective gas. Some early tungsten bulbs used nitrogen alone. An old (1917) source (available online) [1] says carbon filaments were operated at 1600 celsius and tungsten at a higher temperature of 2000 celsius. Carbon filaments were too short-lived (though higher efficiency) if operated near their sublimation temperature. This source also states that nitrogen was used as a fill gas for tungsten filament bulbs. A newer book (1994) says again [2] that carbon filaments are only operated up to 1750 C while tungsten filaments are operated at 2400 to 2750 C with fill gas of argon or nitrogen. Edison ( talk) 23:48, 18 April 2008 (UTC)
Regarding Omegatron's question, this link does unfortunately not answer it but it says that when light bulbs are broken it's mainly tungsten(VI) oxide. This document which is not freely available should answer the question. Icek ( talk) 03:08, 19 April 2008 (UTC)
I read that in a previous thread, but didn't want to hijack it. Imagine Reason ( talk) 01:12, 18 April 2008 (UTC)
The very sad historical fact is that per United States Radium Corporation women were reportedly employed to paint "glow in the dark" dials and had to lick the brushes to shape them, thereby ingesting radioactive pigment which caused cancer. Edison ( talk) 05:05, 18 April 2008 (UTC)
What are the web sites of the largest professional societies concerning industrial hygiene? 75.61.111.185 ( talk) 08:48, 18 April 2008 (UTC)
hi!!!!! I would like to ask a question about human powered vehicles. what is the role of "Aerodynamic lift" in human powered vehicles -land?? and how is it countered for the same vehicles??
Please reply as soon as possible Thanking you
Does the US military currently have any plans to adopt NOTAR technology? -- AtTheAbyss ( talk) 13:03, 18 April 2008 (UTC)
I didn't have any imagineary friends when I was little, but I had some imaginary "experiences". For example, i clearly remember rays of bright colors shooting across the night sky, and two goats singing (in human voice) while grazing. There were other, even sillier, incidents too. I believed in these and remembered them just like actual memories until I was grown up enough to realize they couldn't possibly have happened actually. Is there any name (or an article) for such a phenomenon? Thanks. 125.21.165.158 ( talk) 16:01, 18 April 2008 (UTC)
I have noticed that many swimming pool chemical products give two sets of different dosage instructions: one for 'stabilsed' pools, the other for 'non-stabilsed' pools. What is the difference, and how do I know which category my own pool fits into ? Thank you-- 196.207.47.60 ( talk) 16:36, 18 April 2008 (UTC)
There seem to be so many questions about oil recently, and they got me thinking. Will it be possible to chemically syntesise oil? If it will, could it ever be financially viable to do so? Could we improve on oil by making it less polluting or something? If we can't do any of these things, why not? We can make diamonds, right? Michael Clarke, Esq. ( talk) 16:52, 18 April 2008 (UTC)
Yes, we can make diamonds ( synthetic diamond), and yes, we can synthesize oil. It's actually not terribly difficult at all (see synthetic oil, but keep in mind those methods start with other fossil fuels. There are other synthetic methods that can start with plant matter, see Fischer-Tropsch process). As mentioned repeatedly, the main problem is that it costs energy (which should not be surprising to anyone with a basic understanding of chemistry, since oil is usually used as a source of chemical energy). And so it will never ever be energetically viable to synthesize oil, as you'd need to drive the process with an amount of energy greater than you could retrieve by burning the oil you ended up making. But there are other uses of oil, and very important ones. Virtually the entire petrochemical industry relies on oil and other fossil fuels. As such fuels become scarce, it will become financially viable to synthesize such chemicals from plants, and there are some people already doing just that. And there is certainly the biofuel movement to create renewable fuels, not that it would actually be energetically efficient at all, and the current biofuels compete with land for food crops to create even more issues. Someguy1221 ( talk) 17:59, 18 April 2008 (UTC)
There are uses for synthesizing a liquid form of energy, however, if that allows for a greater power-to-weight ratio than the original form. For example, let's say you have electricity from solar, wind, hydro, or nuclear sources. You can create cars that run on electricity, but not planes, as the batteries weigh too much and store too little energy to be useful there. So, using the electricity to synthesize some form of liquid fuel may make sense. Also, since the existing car fleet can't easily be switched to electricity, the synthetic fuel may make sense during the transition period for cars, as well. StuRat ( talk) 19:20, 18 April 2008 (UTC)
There is much more to automotive fuel than the fact that ancient solar energy is stored in it and that it provides net energy greater than the energy needed to extract refine and transport it to the filling station. Liquid hydrocarbon fuel is presently a far denser form of energy, both by space and by weight, than other forms of portable energy which could be used to power cars such as batteries. There should be a market for synfuel even if it takes more energy to produce than it provides to the car. The input energy used in the synthesis could be something green like a solar array on the roof of a residence or something less green like a breeder reactor. The end result should be a source of energy that will power a car at highway speeds as far as a tank of gas presently does. After over 100 years of electric cars, batteries still suck at energy density compared to liquid fuel. Some process which converts plant material to auto fuel, or which provides hydrogen fuel, even with a greater energy input than the energy the fuel ultimately delivers to the car, would be of interest. We are expected to arrive at the year when the maximum amount of petroleum is extracted from the ground , and worldwide demand is constantly growing, which will steadily drive up the cost of petroleum as old oilfields are re-worked and less promising fields are exploited in more expensive, sometimes more polluting, and sometimes more water-wasting methods. Edison ( talk) 23:15, 18 April 2008 (UTC)
is there any upper limit to (measure) temperature? plz answer —Preceding unsigned comment added by Harshkothari ( talk • contribs) 19:47, 18 April 2008
No SpinningSpark 21:22, 18 April 2008 (UTC)