From: Roy Mayeda (roy_mayeda@isd743.k12.mn.us)
Date: Thu Jan 09 2003 - 10:01:08 PST
Date: 09 Jan 2003 12:01:08 -0600 Message-ID: <977474818roy_mayeda@isd743.k12.mn.us> From: Roy Mayeda <roy_mayeda@isd743.k12.mn.us> Subject: Re: rust in a bottle
Charlotte,
I think I remember seeing something like this done. In order to increase the rate of the reaction, I think you needed to add an electrolyte to the steel wool -- a little salt and water, or a small amount of a dilute acid solution. Soaking in alcohol should be enough to strip off any oil coating (rust inhibitor), though acetone might do a more thorough job. (It's a little nastier to handle though, so if you're not having any problems with the iron reacting I wouldn't bother changing.)
As an additional note on balloons, I recently did the traditional limiting reactant demo with acid in a flask and admitting a carbonate or bicarbonate in a balloon which caps the flask. The amounts were very carefully measured, but the balloons sometimes inflated to different sizes when stoichiometric and excess amounts of the solid were used (should be the same). Balloons are NOT quantitative! If you do the demo, do a practice run with the individual balloon that will be used in each case to see that the differences in elasticity of the balloons doesn't affect your demo. (Good thing I checked -- had an observation that day!)
Roy Mayeda
Sauk Centre HS
Sauk Centre, MN
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