How do hydrogen and oxygen mix?

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Discussion Overview

The discussion revolves around the mixing behavior of hydrogen and oxygen gases in a confined space, specifically addressing how these gases interact under different conditions, including the implications of gravity and energy input for chemical reactions. The scope includes conceptual understanding and exploratory reasoning about gas behavior and mixing dynamics.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that hydrogen and oxygen mix through diffusion, leading to a homogeneous mixture if allowed sufficient time.
  • There is uncertainty about the behavior of the gases when the bottle is turned upside down, with questions about whether the lighter hydrogen would rise and the heavier oxygen would fall.
  • One participant challenges the idea that the gases would behave differently when the bottle is right-side-up versus upside-down, suggesting gravity's role in the mixing process.
  • Another participant asserts that a small amount of energy can initiate the reaction to form water, countering the claim that significant energy is required.
  • A question is raised about how the gas molecules perceive the orientation of the bottle, indicating a curiosity about the fundamental nature of gas behavior.

Areas of Agreement / Disagreement

Participants express differing views on the effects of gravity on gas behavior and the energy required to initiate the reaction between hydrogen and oxygen. The discussion remains unresolved regarding the specific dynamics of gas mixing and the implications of bottle orientation.

Contextual Notes

Participants have not fully explored the assumptions regarding gas behavior under different conditions, such as temperature and pressure, nor have they clarified the definitions of "lighter" and "heavier" in the context of gas mixtures.

tackyattack
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So I'm curious, if you mix two parts hydrogen and one part oxygen in a bottle, how do they mix? I know that it wouldn't turn into water unless lit on fire. If the bottle was turned upside down and uncapped, would the oxygen fall out the bottom and hydrogen float to the top? Or are the two molecules stuck together so that both would end up falling out?
 
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Ambient conditions? Google "entropy of mixing."
 
tackyattack said:
So I'm curious, if you mix two parts hydrogen and one part oxygen in a bottle, how do they mix?
They mix by diffusion. So, when you start out, they are essentially completely intermixed (provided you've waited long enough).
I know that it wouldn't turn into water unless lit on fire. If the bottle was turned upside down and uncapped, would the oxygen fall out the bottom and hydrogen float to the top? Or are the two molecules stuck together so that both would end up falling out?
First, what do you think would happen if you turned it upside down and it wasn't uncapped?
 
Chestermiller said:
First, what do you think would happen if you turned it upside down and it wasn't uncapped?

I'm not sure. If it was lighter than air, it would float to the top. If it were heavier, it'd sink to the bottom?
 
tackyattack said:
I'm not sure. If it was lighter than air, it would float to the top. If it were heavier, it'd sink to the bottom?
Why doesn't it do that when the bottle is right-side-up?
 
Chestermiller said:
Why doesn't it do that when the bottle is right-side-up?

Because... Gravity...?
 
tackyattack said:
I know that it wouldn't turn into water unless lit on fire.

Not true - it takes very, very little energy to do this. Much less than can be provided by an ordinary spark due to static electricity. I've seen a balloon filled with a 2:1 mixture explode as soon as it touched the ceiling.

When you think about Chestermiller's question - how does the gas know whether the bottle is right side up or upside down?
 
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