Oxygen gas jars

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RosalieL
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Oxygen gas jars

Post by RosalieL »

Any idea how much H2O2 (20 vol/6%) and MnO2 I will need to make 4 gas jars full of oxygen using "the laboratory" collection method?
Marama T
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Re: Oxygen gas jars

Post by Marama T »

Use the name as a clue - "20 volumes" mean that from a given volume of hydrogen peroxide, the decomposition reaction will give off 20 times that volume of oxygen. So I suppose you could use one twentieth the combined volume of your gas jars. MnO2 is just a catalyst in the reaction.
Merilyn1
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Re: Oxygen gas jars

Post by Merilyn1 »

Curious - how successful is this method? Does anyone often do this to collect oxygen? Have a teacher who wants us to buy an O2 cylinder but I'm concerned about storage. Science Assist agrees with my thinking. The come back from teachers has been the difficulty in producing O2 and the cylinder would be easier.
bigmack
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Re: Oxygen gas jars

Post by bigmack »

Making Oxygen from H2O2 seems like a very expensive way to make it .
You can buy disposable bottles of Oxygen from Bunnings .Its used for small Welding setups .Costs about $56 for a 950ml bottle .
https://www.bunnings.com.au/bossweld-95 ... e_p0255938

Or you can go big and for @200 deposit and $70 a refill you can have a bottle of Oxygen like they use in TAS with Oxy acetylene setups .
https://www.bunnings.com.au/coregas-tra ... s_p5910224

I don't see why storing a bottle of Oxygen in a Science Lab is any more risky than storing one in TAS or any other workshop .
I'd be surprised if your TAS dept wouldn't loan you their bottle when you need it .I know ours would . :thumbup:
Merilyn1
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Re: Oxygen gas jars

Post by Merilyn1 »

As it is hazardous, you still need to consider storage requirements based on information contained in the SDS. A risk assessment needs to be done on where and how to store the cylinder, safe handling procedures and training requirements. As I have not had any experience or training with handling gas cylinders in the workplace, I do not want to commit to having them in Science without training.
When you add it all up, the bottle of H202 isn't that expensive.
RosalieL
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Re: Oxygen gas jars

Post by RosalieL »

Marama T wrote: 15 Jun 2022, 09:29 Use the name as a clue - "20 volumes" mean that from a given volume of hydrogen peroxide, the decomposition reaction will give off 20 times that volume of oxygen. So I suppose you could use one twentieth the combined volume of your gas jars. MnO2 is just a catalyst in the reaction.
I had always wondered what the 20 vol meant!
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melsid
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Re: Oxygen gas jars

Post by melsid »

To harvest oxygen and hydrogen easily, we have a dedicated setup for each. Burette into the stopper of a side arm conical flask dispensing the H2O2 or the 5M HCl. In the flask is either the MnO2 or Mg ribbon. We then bubble the gas out through a water bath and a beehive and into the container we need to fill.
Works everytime, and sooooo easy! No more stained black ceilings from Mel being too slow at getting the stopper onto the flask!

And in answer to your question RosalieL, it only takes a small amount of MnO2 to get your oxygen. Maybe half a spatula or so. Using the burette to dispense the H2O2 you only use what you need.

Hope this makes sense, I'll take a pic when I have more time if anyone wants to see it...
Merilyn1
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Re: Oxygen gas jars

Post by Merilyn1 »

Hey I'd love to see a photo!
RosalieL
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Re: Oxygen gas jars

Post by RosalieL »

melsid wrote: 16 Jun 2022, 09:21 To harvest oxygen and hydrogen easily, we have a dedicated setup for each. Burette into the stopper of a side arm conical flask dispensing the H2O2 or the 5M HCl. In the flask is either the MnO2 or Mg ribbon. We then bubble the gas out through a water bath and a beehive and into the container we need to fill.
Works everytime, and sooooo easy! No more stained black ceilings from Mel being too slow at getting the stopper onto the flask!

And in answer to your question RosalieL, it only takes a small amount of MnO2 to get your oxygen. Maybe half a spatula or so. Using the burette to dispense the H2O2 you only use what you need.

Hope this makes sense, I'll take a pic when I have more time if anyone wants to see it...
That sounds like a great set-up! Yes, I'd love to see a photo when you get a chance!
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