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Is oxygen that comes out from a car and regular oxygen the same (exactly identical)

  1. Jun 22, 2012 #1
    Is oxygen that comes out from a car and regular oxygen the same (exactly identical) except that one is warmer than the other?
     
  2. jcsd
  3. Jun 22, 2012 #2
    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    How/where/when does oxygen come from a car?
     
  4. Jun 22, 2012 #3
  5. Jun 22, 2012 #4
    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    Oxygen is oxygen. Nothing sets one molecule apart from any others.
     
  6. Jun 22, 2012 #5
    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    so its not like atoms can have different levels of energy. I was just curious if a element is used in combustion does it use energy and is not the same or something like that
     
  7. Jun 22, 2012 #6
    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    The oxygen that comes out is not the same as ordinary oxygen, even stronger: it's not oxygen anymore at all! In the engine the oyxgen gets transformed to (among other things) carbon dioxide. It's this carbon dioxide that your car releases, and that is definitely not the same oxygen. It's very unhealthy to breath in carbon dioxide.
     
  8. Jun 22, 2012 #7

    DaveC426913

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    Let's set a couple of things straight.

    There is atomic oxygen and there is gaseous (molecular) oxygen.
    Atomic oxygen is exactly that - single atoms of the element oxygen, symbolized by O.
    Atomic oxygen loves to bond to virtually anything, including itself. Two oxygen atoms will bond and form O2 (O=O) as gaseous oxygen molecules. This is what we breathe. We rarely encounter atomic oxygen in every life.

    It is also possible for three oxygen atoms to bond to form O3 (O-O-O), which is called ozone, but I won't go into detail about that here.

    Now, according to that PDF (page 6, bottom graph), one of the byproducts (10%) of diesel combustion is indeed O2. This is everyday plain old breathable oxygen. So that's the answer to your question.


    However, an extremely strong note of caution: other byproducts of combustion are extremely toxic. Notably Carbon monoxide CO (C=O). This, just like oxygen, is odorless, colourless and highly mixable with oxygen. So, there is no practical way of separating oxygen from carbon monoxide. If you were to try to separate out oxygen from the exhaust, you would not separate the carbon monoxide, meaning you would be breathing it too. Carbon monoxide can kill you. Silently. You will never know it, you will just fall asleep.

    Do not do.
     
    Last edited: Jun 22, 2012
  9. Jun 23, 2012 #8

    D H

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    The air we breath out contains 13 to 16% oxygen. That doesn't mean we produce oxygen. It just means our lungs don't take up all of the oxygen in the air that we breath in. We run lean.

    Diesel engines similarly don't produce oxygen. They just don't use all of the oxygen in the air fed into the engine. They run on a lean air to fuel ratio. They have to do so because of the nature of how diesel engines work.


    The OP is talking about diesel engines, not gasoline (petrol) engines. Gasoline engines operate at very close to a stoichiometric ratio. The exhaust from a gasoline burning car ideally contains no unburned fuel, no unburned oxygen. Diesel engines run lean. The exhaust contains oxygen.
     
  10. Jun 23, 2012 #9

    NascentOxygen

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    Someone called? :smile:

    There isn't a whole lot of everyday talk about oxygen from car exhausts, but of course there are just as many oxygen atoms emerging from the exhaust as enter via the air filter and fuel*. Combustion is a conservative reaction: no atoms are created or destroyed, they merely change partners. There is no favouritism: isotopes are all treated equally.
     
  11. Jun 23, 2012 #10

    D H

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    ybhathena clarified the question raised in the opening post in post #3. The question is about O2 in the exhaust from diesel engines.
     
  12. Jun 23, 2012 #11

    krd

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    No. It's not unhealthy to breath in carbon dioxide. You do it all the time. (of course you don't want to be in a position where carbon dioxide is the only thing you have to breath.)

    The real dangerous gas - when it comes to any combustion source is carbon monoxide. It's an intermediary to the formation of carbon dioxide. If you're in an enclosed space and you have something like a malfunctioning gas burner, the carbon monoxide from it can kill you - and kill you really quickly. Carbon monoxide binds to the haemoglobin in your blood stream - stopping it from carrying oxygen. And if that happens, you fall asleep and then you die.

    It is dangerous. If you're ever using a gas burner indoors you need to have the room well ventilated. The carbon monoxide can build up and kill you before you know it. I know a terrible story about a family living in an old house - they had the windows redone, lots of insulation, but no design for ventilation. Used their gas heater - and died.


    One thing that drives me crazy with the whole global warming thing is people thinking carbon dioxide is a poisonous gas. It's possible the most important gas on the planet for the existence of life.

    I once had to tell a worried little friend, that carbon dioxide does not actually cause lung cancer. And that it is not always a man made gas.
     
  13. Jun 23, 2012 #12

    D H

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    Mr Vodka was correct. It is unhealthy to breath CO2 in high concentrations. Carbon dioxide concentrations of 15% or higher are very deadly. Concentrations between 10 to 15% will also kill; it just takes a bit longer. Even though diesel exhaust contains 10% oxygen (about the same as the partial pressure atop a 5500 meter tall mountain), that diesel exhaust contains about 12% CO2 is what makes it deadly (short term).

    That is not the case with diesel engines. They run lean. They don't produce much carbon monoxide.
     
  14. Jun 23, 2012 #13

    NascentOxygen

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    Re: Is oxygen that comes out from a car and regular oxygen the same (exactly identica

    Then generalised it in post #5.
     
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