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MIT+K12
Course: MIT+K12 > Unit 1
Lesson 1: Chemistry and biology- Why we fart
- Solving biology's mysteries with plants
- Why do we have snot?
- How do braces work?
- Squid skin with a mind of its own
- Why can we regrow a liver (but not a limb)?
- MIT's choose-your-own: Chemistry adventure
- The food chain
- Homeostasis
- Bread mold kills bacteria
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MIT's choose-your-own: Chemistry adventure
How do simple things like yeast, soap, and hydrogen peroxide come together to create a foam-splosion reaction? Tweak the ingredients to find out in this choose-your-own-adventure video series!
Want to join the conversation?
- Nothing happens when I try to click on the ingredients! What do I do?(8 votes)
- Am I understanding it correctly that the best way to create more bubbles would be to add more hydrogen peroxide to the mixture (>12%)? The yeast (catalase) and dish soap doesn't get used up, so more hydrogen peroxide would result in more oxygen gas, and thus: more foam, right?(2 votes)
- Maybe, even if the yeast dosen't get used up, more hydrogen perioxide means more work so I guess more foem but less speed. well try it anwser me back(0 votes)
- why is evryone so intrested in this?(1 vote)
Video transcript
WHITNEY: So this is
hydrogen peroxide. You might recognize it
from your first aid kit, because it's really
good at killing germs. But there's more to this
guy than cleaning cuts. So this liquid is
actually made up of molecules that are constantly
wanting to break apart. Hydrogen peroxide, or
H2O2, is held together by an unstable bond-- this
one, between the oxygen atoms. So the molecule
wants to break down into smaller, more stable
pieces-- H20, or water, and O2, or oxygen gas. Now this breakdown
is usually so slow, we can't even see it happening. But what if we did
want to see it happen? We can speed up this reaction
a lot by using yeast. Yeast makes something called
catalase, and what this does is speed up the breakdown
of hydrogen peroxide, and something that speeds
up a chemical reaction is called a catalyst. And the reason yeast makes
catalase is because hydrogen peroxide damages cells and DNA. So the catalase goes around and
breaks apart hydrogen peroxide, so it can't damage the yeast. And actually our bodies
have catalase too, to protect our cells and DNA. And the cool thing
is the catalase doesn't get used up
at all in the process. So it keeps going
around, breaking apart the hydrogen peroxide, quickly
releasing oxygen gas and water. And normally this
oxygen gas would just get released out into
the air, but for fun, we can trap it in soap bubbles. This is the hydrogen peroxide
you can buy at the drugstore. It's not very strong. It's only 3%. But this one is 30%. I'm diluting this down
with water to 12%, mixing one milliliter of dish
soap, and some food coloring. I'm also taking a gram of
yeast and activating it with four milliliters
of warm water. So what do you think will happen
if we mix all these together? So pretty cool. But can we get even more foam? Can we make it faster? Let's tweak each of the
ingredients one at a time and figure out how they
affect the reaction. Should we change the amount
of hydrogen peroxide, the amount of soap, or
the amount of yeast?