Expected Results:
Results may vary based on materials used, setup, procedure, and other factors, however, here is an example on what to expect:
• When the KI is added to the beaker, foam should start to form immediately. As oxygen is evolved, it causes the dish soap to
foam up.
• When the reaction first starts, you may observe some steam forming above the solution in the beaker, because this
is an exothermic reaction.
• As the foam forms, the weight of the beaker and its contents will decrease until the foam stops forming.
Follow-up/Teaching Notes:
• The dish soap is not necessary for the reaction to occur, it merely creates a visual effect by trapping much of the oxygen
as it is evolved.
• The steam that is produced above the reaction is not oxygen; oxygen gas is not visible. It is a combination of vaporized water
and hydrogen peroxide.
• Adding more soap does not necessarily increase the amount of foam that is produced; it eventually will stifle the foaming
process and create even less foam. Students can be tasked with experimenting with different ratios to determine what is the
optimal amount of soap to generate maximum foam.
Add Inquiry:
• Students can be challenged to calculate exactly how much of each reactant should be used to generate maximum weight loss
of the mixture. Even so, The amount of weight decrease will not correspond exactly to the weight of oxygen that is
theoretically released from the reaction. Students can then discuss reasons why this is the case, from simple human error to
the weight of the steam that is being generated to the role that the atmosphere/gas still inside the beaker may play.
Disposal/Clean-up:
– Foam and remaining solution inside the beaker can be cleaned out in the sink and disposed of via the drain with plenty
of water.
Boom Goes the Beaker Activity
(continued)
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