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Let's Discover: Spewing Pumpkins|
Oct 18
2011
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Let's Discover: Spewing PumpkinsPosted by SarahW in Holidays, Guest bloggers, Discover |
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Your average jack o’lantern is usually a cool face carved into a nice, big pumpkin (which is actually a fruit from the same plant family as cucumber and melon, by the way). We carve pumpkins at the Discovery Centre just like everyone else does, but sometimes we make something other than light come out of them. In fact, we like to make our pumpkins spew! Which may sound gross, but trust us, your kids will love it!
If you would like to try this experiment at home, you will need: a carved pumpkin, some dish soap, some dry yeast and some hydrogen peroxide (more on that below). Food colouring is optional!
Take a tablespoon or so of yeast and mix it with warm water – enough to make it a little runny. Next, pour some peroxide into your pumpkin – if your pumpkin is fist-sized, a few tablespoons will be enough, but for larger pumpkins you may need a small container inside to hold everything. Add a good squirt of dish soap to your peroxide (and colour if you like), and then quickly pour in some of your yeast. Foam should pour slowly out of the openings in your pumpkin giving the illusion of a spewing or “puking” pumpkin, as kids like to say. Yes it’s gross, but fun!
The foam coming from your pumpkin is filled with oxygen, which is produced by hydrogen peroxide as it breaks apart into water and oxygen gas. The yeast you added speeds this up because of natural chemicals it contains. The bigger the pumpkin, the more ingredients you’ll need, and the stronger the peroxide, the faster the spewing will go. First-aid peroxide is about 3% concentration, but you can get 6% (or “20 volume”) for bleaching hair. The stronger it is, the more likely it will bother your skin or eyes though, so an adult should handle the high-test stuff.
With our help, the neighbourhood kids on your block will think you have the coolest pumpkins! For more Halloween fun, join us on October 29 from 5:30 – 8:30 p.m. for Discovery Centre’s Spooktacular Science Halloween Party. It’s bound to be a scream.
For more great things to discover - visit the Discovery Centre on Barrington Street in Halifax, check out their website or join them on facebook.
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Discovery Centre
said:
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Hi Sophie Thanks for your comment. The experiment as written is entirely safe. In the 3% concentration found in pharmacies, the corrosive danger of hydrogen peroxide is almost non-existent. It is sold for use in disinfecting cuts, and for such applications is actually less-painful than alternatives. Peroxide can cause irritation in contact with the eyes or other mucous membranes (as stated in the post), much like many other household products, and as with any other experiments, this one is intended to be conducted with adult supervision. As it says in the experiment, solutions above 3% should be handled by adults exclusively, though it is worth noting that solutions of 6% are used by hair care professionals on our heads in order to bleach our hair. For more information, Snopes.com has a nice article debunking and confirming certain home uses for hydrogen peroxide -- http://www.snopes.com/medical/...oxide.asp. In addition, you should examine the Material Safety Data Sheet for 3% peroxide. The information page from Kids.Net.Au appears to be (it does not, but should say) for very high-concentration hydrogen peroxide ? 30% or more ? which I would only deal with while wearing nitrile rubber gloves and eye protection, as well as adequate ventilation. For comparison, I?ll also include the MSDS sheet for 1M acetic acid, which is slightly-strong vinegar. Hydrogen peroxide: http://sciencekit.com/images/a...345.00.pdf Vinegar : http://sciencekit.com/images/a...M_3.20.pdf The experiment can be performed using vinegar and baking soda if preferred, but due to vinegar inhibiting the bubble-forming (surfactant) abilities of soap, the foam ends up much runnier. It?s worth comparing! Thanks Chris McCain, The Discovery Centre |
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Marcy
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WRT the "danger", c'mon, it is a FIRST AID basic supply! I wouldn't go to the chem lab and pick up concentrated hydrogen peroxide, but I don't see a problem with the commercially available stuff, with obligatory warnings prominently displayed on the bottle. Kids need to learn how to handle age appropriate risk.  |
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sophie
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I think as a childrens activity this should come with a giant warning and should be rewritten. Did you know that Hydrogen peroxide is harmful to children and can burn their hands according to Encyclopedia.kidsnet.au-In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin and can cause severe irritation and even death. So please why not rewrite this using baking soda and vinegar its a less hazardous ingredient and will froth just as well. Sophie-Editor at Eco arts and Crafts for Children. |
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