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Q & A: Hydrogen + Oxygen = Water ?

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Q:
I am going to do the water+hydrogen and oxygen. I have looked all over the internet for info but i can’t find any. Can you reference any sites for me? Thank You
- Brently (age 12)
Tri-County, Remington, IN, USA
A:
Brently -

I think that the reason that you can't find any information on this is because it is not a very safe thing to do. To combine hydrogen and oxygen to make water, you basically have to mix the gases together and light them with a match. Just mixing the gases together isn't enough - you have to do something to get the chemical reaction started. The problem is that this creates a big explosion. I've seen this done as a demonstration by college professors (under very controlled circumstances), but it's really not something that you should try at home. A famous example of a hydrogen/oxygen explosion performed under uncontrolled circumstances is the deadly 1937 explosion of the Hindenburg zeppelin in New Jersey:



For this reason, no one fills large balloons with hydrogen anymore, preferring the much safer non-flammable helium for blimps.

There are plenty of other chemical reactions that you could do to make water. For instance, you can mix an acid like vinegar with a base like baking soda. This reaction will produce lots and lots of bubbles (carbon dioxide) as well as water. (But you shouldn't drink it - it will have sodium acetate in there too.) For a page on how to do the experiment, look here.

-Tamara, Tim, & Tom

(republished on 07/13/06)

Follow-Up #1: water from hydrogen?

Q:
We all know about the huge water crisis thatís going to hit us sooner or later. Some of the solutions that are being coming up include desalination of sea water and recycling water. Can hydrogen bonding save the day? Humans can make water but can we actually make enough to provide for whole nations on a long term basis or are there just too many complications?
- Kiki (age 13)
Jobury, South Africa
A:
Nearly all the hydrogen which people talk about using for fuel would come from using other energy sources to take apart water molecules. (That's why hydrogen is not a new energy source, just another way of carrying energy around.) Of course that also means that hydrogen is not a new source of water either. Converting water to hydrogen and oxygen and then letting them recombine is one way of purifying it, but probably one of the least efficient ways.

Mike W.

(published on 09/04/07)

Follow-up on this answer.