Sciencemadness Discussion Board

some basic questions to disprove lies

Berrilium - 17-4-2012 at 10:09

I am doing a project at school and my partner seems to be pulling 'facts' out of thin air.

A) he says that the gas at home that burns only gives off blue flame due to methane. This can't really be true...
B) we are collecting methane and to purify it he wants to pass it through steel to remove oxygen - it wouldn't oxidize fast enough would it?
C) he says there are 'free roaming' hydrogen and oxygen atoms in water - oxygen yes... Hydrogen I don't think so

Thanks

DerAlte - 17-4-2012 at 10:24

Try pulling your facts out of a book or Google or Wiki.

Der Alte

Brominator - 17-4-2012 at 10:32

The colour from a flame comes from the heat exciting molecules causing them to lose energy by emitting light of a particular wavelength(emission spectra) and as far as i know the blue colour is not specific to methane as a butane flame can also be blue so is probably due to the formation of radicals or other decomposition products.
as for the steel i doubt passing it though a steel tube will have little or no affect on the oxygen concentration, to remove oxygen at standard temp and pressure to stop the methane becoming an explosive hazard would be hard with easily available chemicals.
and as for your last question there are oxygen molecules not free atoms but for hydrogen because it is a very light gas it easily escapes the earth atmosphere leaving a very small percentage indeed of the atmosphere being diatomic hydrogen
Hope that answered your questions.

Adas - 17-4-2012 at 10:38

The flame would be otange if there wasn't enough oxygen - Unburnt carbon particles emit orange light.

Pyridinium - 17-4-2012 at 18:05

Quote: Originally posted by Berrilium  
I am doing a project at school and my partner seems to be pulling 'facts' out of thin air.

A) he says that the gas at home that burns only gives off blue flame due to methane. This can't really be true...
B) we are collecting methane and to purify it he wants to pass it through steel to remove oxygen - it wouldn't oxidize fast enough would it?
C) he says there are 'free roaming' hydrogen and oxygen atoms in water - oxygen yes... Hydrogen I don't think so

Thanks



A. Propane and acetylene both burn with a blue flame. So do many other gases - as Brominator said, butane is another one.

B. I think Brominator is right. The only thing that might make it practical is if the steel were very finely divided (fine wool), the air moist, and the contact time very long. Because of the formation of iron oxide, it is a one-way reaction essentially, so at least you'd have that.

C. The closest thing to this would be "free roaming" ions, but hydrogen ions in water are actually H3O+. Other than that, H2O molecules do not come apart in water unless there is some electrolytic action. "free roaming" oxygen would be due to dissolved atmospheric oxygen, not from the water.

DougTheMapper - 17-4-2012 at 18:26

Turn the gas stove on low and it burns blue. Turn it up and it's yellow.

A bunsen burner has a yellow flame with the air ports closed. The color of a methane flame is dependent, as mentioned above, on the amount of unburned carbon present.

Vikascoder - 18-4-2012 at 01:55

Gas available for cooking purposes is butane and it gives blue colour when there is good supply of oxygen and gives yellow when there is insufficent supply of oxygen . Same case is with acetylene to check it drop calcium carbide in water then burn the gas which is liberated then burn it in complete supply of oxygen notice the difference in colour

dann2 - 18-4-2012 at 13:16


Ask your friend for a demonstration on the burner that is burning the Methane.
Before the demonstration (you will have to have access to the burner in question) rub lots of common salt around the burner or perhaps brush some strong concentrated salt solution around and inside the outlets of the burner. When the burner then starts up it will burn with an orange flame only!!!!!!!!! due to the presence of the salt.

You can then look him in the eye and shrug your shoulders. ;) ;) ;)

adamsium - 20-4-2012 at 01:19

IIRC, I believe that the yellow flame seen, for instance, when a bunsen burner has its air port closed, is due to the carbon 'dust' that results due to incomplete combustion. The carbon is heated greatly by the flame, and becomes incandescent for a short time as a result. This can also be seen in a candle flame, due to inefficient combustion of the wax.

adamsium - 20-4-2012 at 01:27

I found this video that nicely explains precisely what I was talking about : http://www.youtube.com/watch?v=ZmtbMKJLUJo

For anyone who hasn't seen this particular youtube channel, their videos are well worth a watch.