Sciencemadness Discussion Board

Oxygen-Hydrogen Flame temperature Mystery

AndersHoveland - 20-1-2012 at 21:53

Is it true that a mixture of oxygen and hydrogen that immediately created from the electrolysis of water will burn at at a higher temperature than if the oxygen and hydrogen come from tanks? I had read that the flame from an oxyhydrogen-water welding torch is significantly hotter than the flame from a simply burning oxygen and hydrogen together.
http://www.display-wholesale.com/servlet/the-21/Sign-Making-...

What could be the explanation for this?

The energy difference between ground state and singlet oxygen is 94.3 kJ/mol. Singlet oxygen in the gas phase is extremely long lived (half life of 72 minutes).

At room temperature, hydrogen gas contains 75% orthohydrogen and 25% parahydrogen. When hydrogen gas is liquified into liquid hydrogen, this proportion is still preserved, but the equilibrium will gradually shift to parahydrogen. The orthohydrogen fraction in the liquid state will release heat as it spontaneously converts into parahydrogen. The heat released during its decay can boil off as much as 50% of the original liquid. If I remember correctly, it takes around 2 days for all the ortho- liquid hydrogen to spontaneously revert into the para- liquid hydrogen, unless a catalyst is used (such as ferric oxide or activated carbon).

Could it be possible that the oxygen from the water torch contains a proportion of the singlet state, and/or that the hydrogen exists in a higher proportion of orthohydrogen than it does from a compressed tank?

[Edited on 21-1-2012 by AndersHoveland]

Mr. Wizard - 20-1-2012 at 22:24

I must admit I don't know the exact state of the hydrogen and oxygen atoms or molecules, but I do know they would be saturated with water vapor at it's partial pressure determined by the temperature and composition of the electrolyte. The partial pressure of the electrolyte would differ from water, but it would definitely be a factor in cooling the flame.

watson.fawkes - 21-1-2012 at 07:16

Quote: Originally posted by AndersHoveland  
Is it true that a mixture of oxygen and hydrogen that immediately created from the electrolysis of water will burn at at a higher temperature than if the oxygen and hydrogen come from tanks? I had read that the flame from an oxyhydrogen-water welding torch is significantly hotter than the flame from a simply burning oxygen and hydrogen together.
http://www.display-wholesale.com/servlet/the-21/Sign-Making-...

What could be the explanation for this?
Gullibility. The link you cited is to a commercial vendor of water electrolysis torches. Perhaps if you cited a scientific paper your premise would be more worthy of attention.

AndersHoveland - 21-1-2012 at 12:36

No, I found a more credible source more than a year ago that compared the two flame temperatures and gave values for the two in Kelvin. The problem is that I cannot find it now.

This source is revealing, but it does not give the exact details of the flame temperature difference
http://keelynet.com/energy/oxyhyd2.htm


[Edited on 21-1-2012 by AndersHoveland]

watson.fawkes - 21-1-2012 at 13:49

Quote: Originally posted by AndersHoveland  
The problem is that I cannot find it now.
How convenient. Perhaps the dog used to eat your homework, too.
Quote:
This source is revealing, but it does not give the exact details of the flame temperature difference
http://keelynet.com/energy/oxyhyd2.htm
No, it really does seem to be gullibility. You're citing KeelyNet, a purveyor of fringe science, pseudoscience, quackery, and fraud.

dann2 - 22-1-2012 at 10:22

Quote: Originally posted by watson.fawkes  
..........aNo, it really does seem to be gullibility. You're citing KeelyNet, a purveyor of fringe science, pseudoscience, quackery, and fraud.


Wall street and Co. do that all the time and seem to have lots of followers?