Make a fart with science

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Make a fart with science
Age Range 3-5 (PreK-K), 5-8 (grades 1-2), 8-11 (grades 3-5)
Group Size small (1-5), medium (6-20)
Setting indoors
Setup Time very long (1 day+)
Duration medium (11-30 min)
Subjects bacteria, fermentation
Materials beaker, banana, balloon
Presentation Style demonstration

Brief Description

Create a fart in the lab using a rotting banana. Students learn about about bacteria eat rotting food and cause fermentation.

Scientific Background

Flatus (intestinal gas) is mostly produced as a byproduct of bacterial fermentation in the gastrointestinal (GI) tract, especially the colon. Over 99% of the volume of flatus is composed of non-smelly gases. These include oxygen, nitrogen, carbon dioxide, hydrogen and methane. Nitrogen is not produced in the gut, but a component of environmental air. Hydrogen, carbon dioxide and methane are all produced in the gut and contribute 74% of the volume of flatus in normal subjects. Methane and hydrogen are flammable, and so flatus containing adequate amounts of these can be ignited.

The remaining trace (<1% volume) compounds give flatus its smell. Recent evidence proves that the major contribution to the smell of flatus comes from a combination of volatile sulphur compounds (VSC). It is known that hydrogen sulphide (H2S), methyl mercaptan, MM (also known as methanethiol, MT), dimethyl sulphide (DMS), dimethyl disulphide (DMDS) and dimethyl trisulphide (DMTS) are present in flatus. The benzopyrrole volatiles indole and skatole actually have a mothball type smell, and therefore probably do not contribute greatly to the characteristic smell of flatus.

This Is How You Play

  1. Remove the peel from a banana.
  2. Smush the banana into a mush.
  3. Place the banana a 3 tablespoons of water into a beaker.
  4. Place a balloon over the top of the beaker.
  5. Leave beaker in the sunshine.
  6. After a few days, take off the balloon and smell your very own lab made fart!

See Also


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