Science Experiments

This is an experiment that you can try with children. It’s super-fun and very fast, so there’s an immediate payoff, and you can run it many times. You can simply run it with the children or you can teach them a little bit about what’s happening, depending on how old they are and how interested they are. Or you can just have a read and see the results through my camera below 😉

I first did this experiment for a university open day, back when I was teaching prac classes during my first postgraduate degree. The day was devoted to primary school children and it was so much fun to see such wonder and excitement from them.

 

What will you need?

  • a glass dish (I’ve used a tall beaker, but a short flat glass dish works well)
  • a styrofoam cup (or quite a few of them!)
  • acetone (you can get this from your hardware store, or some pharmacies)
What do you Need?
What do you Need?

 

What will you do?

It’s quite simple.

  1. Pour a small amount of acetone into the dish, about 1cm deep.
  2. Carefully place your styrofoam cup onto the liquid surface.
  3. Watch in amazement and delight 🙂

 

What will you learn?

There are two lessons today. The first is learning about plastics. A styrofoam cup is a type of plastic – a little different to what you might normally consider to be plastic, but all plastics are made of long chains of repeating molecules. Each individual molecule is called a monomer, so when there are many joined together, you have a polymer (you’ve probably heard of polymers?). Plastics are polymers. Styrofoam is different to some other plastics because the long chains are held together quite loosely by non-polar bonds (more on this later). Also, when they make this particular plastic, they make is as a foam (hence the name styrofoam), so there are a lot of air spaces between the molecules.

The second lesson is about polarity and the theory that like-dissolves-like). Let me explain. Molecules either have a charge (polar) or they don’t (non-polar). When the parts of the molecules bind together, they share electrons, and sometimes, one of the atoms attracts more of the electrons than the others. Electrons are negatively charged, so if one side has more electrons, then that side becomes negatively charged. Now that there’s less electrons on the other side, that side becomes positively charged. This is now a polar (or charged) molecule. Water is an example of a charged molecule. The oxygen atom in water attracts more electrons than the hydrogen atoms do, so it becomes a charged molecule. Our styrofoam however, has the charges spread out evenly, it has no charge overall, so it is non-polar.

Oil is another example of a non-polar substance. We all know that water and oil don’t mix (perhaps another experiment another time). This is because of the theory that “like dissolves like”. Polar substances will dissolve in other polar substances. So, this means that water won’t dissolve styrofoam. Remember – water is polar, styrofoam is non-polar, so they won’t dissolve. Now, let’s talk about acetone. This is the chemical we use to remove nail polish, particularly the gel polishes that are popular now. The polish is non-polar and so the acetone will dissolve it because it is also non-polar. Since styrofoam is non-polar and acetone is non-polar, like-dissolves-like and the so the acetone dissolves the styrofoam.

As an extra, since the styrofoam is a foam, there are a lot of air spaces between the molecules so lots of gaps for the acetone to seep in and so the reaction is quite fast. It looks like the cup is melting, but it’s actually dissolving. I remember doing this experiment so many times over the two days, probably dissolving 100 cups. At that time, I used a glass petri dish (flat round dish) and had it sitting on a black laboratory bench. The children were trying to see under the bench to see the cup coming out the other side 🙂 They thought it was magic.

Bubble away...
Bubble away…

What do you think? Do you think children will be excited by this? I know I still am? Whether you learn something or not, it’s very cool to watch. The acetone looks like it’s boiling around the cup, but it’s just the air escaping from within the foam.

Such a cool experiment! Or is it just me?

x desleyjane


Safety Considerations.

  1. Do not eat anything in this post – none of it is edible!
  2. Acetone is flammable and harmful if ingested or inhaled.
  3. It will dry your skin (acetone dissolves the oils in your skin).
  4. Do not breathe in the vapours – run this experiment in a well-ventilated area.
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Posted by:desleyjane

photographer, blogger, planner, scientist, dog lover, frequent flyer, daughter, sister, BFF, human

32 replies on “Where’s My Coffee ?!?

  1. I worked in an open lab as tutor for kids and students during my studies. It was always fun doing these kind of experiments with them. They are excited and eager to learn how this works, I am sure your reader’s kids will love it as well

    Liked by 2 people

  2. I loved the experiment and I understand why kids love it too.
    It’s not complicated to replicate and the way you explain it, even someone with monomer type of gray cells, like me, will get it. lol
    There is a science museum for kids in Amsterdam, and I will add to your list too. Kids spend hours busy with science experiments. It’s lots of fun. Adults enjoy immensely too. I have been there countless times.
    Thanks for this marvelous and very informative post. You’re educating us.
    Xxx

    Liked by 1 person

  3. This is very cool! I had no idea about the strength of acetone! I think kids would enjoy watching this… Thanks for the safety tips too…
    I wish the snow here in NYC would melt as fast as that cup!
    Have a lovely Thursday !

    Like

    1. Yes hun, it really is. That’s why it dries your skin out and makes it cold, it’s dissolving the oils in your skin. Be sure to moisturise straight after removing polish. But a lot of removers are acetone-free these days…x

      Like

  4. You remind me of my chemistry teacher. He brought a jar of lighter fluid (butane) and a test tube to class on the first day. He ejected the butane into the test tube and let us watch it boil in front of our own eyes.

    To show how volatile that alkane was, he just splashed the content of the test tube on the floor. By the time the liquid had hit the floor, most of it had evaporated.

    That was quite the impression.

    Liked by 1 person

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