Science Buddies: "Ask an Expert"

Science Buddies Experts,
Please help! I am a K-5 Technology and Supplemental Science teacher trying to complete a school-wide science fair. We have relied on this site for so many of our experiments. With one second grade class I was going to do an oxidation experiment with a salt peter solution. This experiement came from an older book - pre 9-11. The idea was to make a salt peter solution and draw a picture on regular paper with it. After it had dried use a match (struck and immediately blown out) to provide heat and start the oxidation process. Since 9-11 and the alternative uses for salt peter, I have been unable to find it locally. Is there a SAFE alternative that would create a similar effect of "drawing with fire" that I could use with these students? They really had their hearts set on this one!

Thank you so much for any help you may be able to provide!
Mrs. Kennedy

Hi jkennedy,

Doing a websearch for "saltpeter" seems to find places where saltpeter is still for sale.

If you input "saltpeter for sale" into google.com, you'll get back several sites among them:

1. http://secure.sciencecompany.com/Potass ... 7C670.aspx
and
2. http://www.amazon.com where you can enter "saltpeter" "saltpetre", or "potassium nitrate" in the search box.

I cannot vouch for either of these sites, caveat emptor.

Hi,

Assuming you just want to write or paint in invisible ink, and then make the message/drawing visible, here is a site that gives several ways to do it very safely (you have to scroll down a whole screen to see them:

http://www.kidzworld.com/article/3844-m ... ink-appear

http://www.kid-craft-central.com/invisible-ink.html

http://starryskies.com/articles/dln/6-01/invisible.html

Obviously the original experiment is still around post 9-11, and it looks quite easy to buy nitrate salts over the internet, seemingly without Dept of Homeland Security hassles, particularly if you only want small quantities. Here are websites that describe the experiment:

http://www.creative-chemistry.org.uk/ac ... riting.htm

http://www.practicalchemistry.org/exper ... 80,EX.html

The advantage of the invisible ink versions is that there is less chance of fire, though with the temperature sensitive inks you might have to use something like a flatiron to make the writing visible.

There are some slight risk ideas on this site that you could consider:

http://blog.modernmechanix.com/2007/10/ ... -in-magic/

Hope this helps!

Best regards,

Barrett Tomlinson

Lemon juice would be my choice. Easily obtained at most grocery stores. Almost any weak acid solution will oxidize plenty of the OH bonds in the celulose chains which will cause that area of the celulose to turn brown when heated.

Hi Mrs. Kennedy - Did you find a solution? I see Science Buddies experts offered several sources and suggestions for a safe alternative. Please do let us know what you tried and how it worked!

Amy
Science Buddies

Amy,
I was asking one of our local high school teachers about what she might recommend for ordering or a replacement. She told me she had the correct chemicals and equipment available and would even send some of her AP Chemistry students over to help the second grade students. We are planning the dates and times now.

Thank you all for your suggestions. I will try to post again to report our results.