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filling soap bubbles with gas from electrolysis

filling soap bubbles with gas from electrolysis - Chemistry Forum

filling soap bubbles with gas from electrolysis - Chemistry Forum. Discuss chemical reactions, chemistry.


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  #1  
Old 10-07-2003, 10:28 PM
dave e
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Default filling soap bubbles with gas from electrolysis



I have seen vague descriptions of demonstrations in which bottled
hydrogen and oxygen are used to blow free floating soap bubbles, which
can then be ignited.

Is there a simple set up which can be used to fill soap bubbles with
hydrogen and oxygen gas generated directly from electrolysis?

I found that sticking my electrodes in soapy salt water just generates
a lot of dense tiny bubbles, which don't ignite.

Running the gasses through a tube dipped in a bit of soap works OK,
but the bubbles tend not to be released from the tube, and they pop
before they become free floating. For safety reasons, I don't care to
ignite soap bubbles while they are still attached to a tube which is
attached to my electrolysis glassware (well, OK, I tried it once with
predictably unsafe results).

Bottom line: What does it take to get soap bubbles to release from a
tube before they pop?

Dave
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  #2  
Old 10-08-2003, 08:33 AM
dave.lister@web.de
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Default filling soap bubbles with gas from electrolysis

> Bottom line: What does it take to get soap bubbles to release from a

invert gravity.

No serious, what reason should a bubble have to release itself from
the "heap of foam". Gravity sux. I guess the lower density of H2/O2
mixtures compared to air are not enough to make up for the bubble's
adhesion to the foam. Maybe a stronger gas stream will work, like you
did when you blew bubbles as a kid. This is a bit of a tricky thing
with a gas that goes bang for a hobby.
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  #3  
Old 10-08-2003, 04:08 PM
dave e
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Default filling soap bubbles with gas from electrolysis

[Only registered users see links. ] wrote in message news:<82c9d2ee.0310080033.63777973@posting.google. com>...

Not a hobby, really. Trying to set it up as a classroom demo. I have
the necessary safety shield and all that.

What I'd eventually like to do is hook the electrolysis apparatus up
to a hand crank power generator, to demonstrate transformation of
energy. From mechanical energy (hand crank) to electrical energy, to
chemical potential energy, to heat and sound energy. I've already
been successful running the electrolysis with a hand crank. It's just
that last energy transformation I need to optimize.

You're right about inverting gravity (or at least inverting the hose
that the bubbles are emerging from). I'll try that later today.

Dave
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  #4  
Old 10-08-2003, 11:35 PM
Buckleys
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Default filling soap bubbles with gas from electrolysis

dave e wrote:

Run the gas from the electrolyser through a 1/2" or bigger tube and into
the soap solution. Might have to jig about the conc. of the soap - I
just use dishwashing liquid with a bit of glycerol. Works fine. I don't
use an electrolysis setup for this demo, just a Buchner flask with a
stopper, aluminium foil and NaOH solution. No cogeneration of oxygen
that way.

Rob.
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  #5  
Old 10-09-2003, 07:26 AM
dave.lister@web.de
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Default filling soap bubbles with gas from electrolysis

> > did when you blew bubbles as a kid. This is a bit of a tricky thing

hehe.. i meant to say that it was the gas's hobby to go bang :-)...
good luck with the demo!
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  #6  
Old 10-10-2003, 02:27 AM
cotoole
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Default filling soap bubbles with gas from electrolysis

[Only registered users see links. ] (dave e) wrote in message news:<10ffa4e4.0310080808.3a52b26c@posting.google. com>...

What I do is set up an electrolysis system in a jar with a rubber
stopper and two large screws going through the stopper and into the
jar. You also need a piece of rubber tubing coming outof the stopper
about three or four feet long. It has to be sealed so all the gas
goes out of the tube and does not leak elswhere. Put a salt in the
water to help with the conductivity of the water (but not a chloride
salt or you will end up with chlorine gas) and hook up the screws to a
positive and negative charge. The rubber tubing - about 1/4 inch
round tubing - will go into a beaker of soapy water. When you crank
the juice, the bubbles that form in the beaker will build up and up.
I scoop them up with a wet spoon and ignite. It will make a pretty
bit explosion and pop quite loud if you get enough bubbles. The kids
LOVE it!!
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  #7  
Old 10-10-2003, 02:31 AM
cotoole
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Default filling soap bubbles with gas from electrolysis

Buckleys <[Only registered users see links. ].au> wrote in message news:<[Only registered users see links. ].au>...



Look above -- I responded in an above message....
colleen.
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  #8  
Old 10-18-2003, 12:53 AM
John Savage
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Default filling soap bubbles with gas from electrolysis

[Only registered users see links. ] (dave e) writes:

I think most simple setups probably generate the gas at too low a rate to
usefully inflate bubbles directly. (Water loss from the surface of the
slowly growing bubble due to evaporation probably causing the bubble to
burst long before lift would cause it to release.) You might try
inflating a prestretched balloon tied over the mouth of the generating
apparatus, and then when the balloon is full generate a bubble from that.
Hydrogen would diffuse through the rubber faster than does air, but a
reasonable rate of generation should make this unnoticeable.

You might consider allowing the gases to mix, and inflating bubbles with
the O2-H2 mixture. Ignite the bubbles only after they have floated well
clear of the gas reservoir. Exercise caution.
--
John Savage (news address invalid; keep news replies in newsgroup)

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