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Fun with M & M's

Tom Kuntzleman's picture
Sat, 05/04/2013 - 06:35 -- Tom Kuntzleman

I came across a simple, yet interesting experiment that was first described by Elizabeth Sumner Walter in 2001. She merely had students pour water into a dish containing some Gobstoppers candies. I showed this experiment to some of my college chemistry students while they were working on a different laboratory experiment. Two of my students, Nathan Ford and Rachel Hubbard captured some video of this experiment, except that they substituted M & M’s candies for the Gobstoppers. You can see this experiment below:

The experiment sparked a lot of interest and discussion. Questions and comments ranged from “what is going on?” to “what happens if you use hot water?” and “Why don’t we try adding some soap?!” The most common question I heard was “why don’t the colors mix?”

A few students got online, and found one website on which it is claimed that the colors don’t mix due to a layer of water insoluble wax on the candies. It is claimed that this wax forms a shield that prevents the water soluble dyes from mixing. Indeed, carnauba wax is listed as one of the ingredients in Gobstoppers candy. However, carnauba is NOT listed in the ingredients in M & M’s.

We decided to test the claim that a waxy candy coating prevents mixing. If this is indeed the wax that prevents the colors from mixing, then its presence should be important in seeing this non-mixing effect. We tested a variety of candies (Gobstoppers, Dubble Bubble Gumballs, Skittles, Spree) that contained carnauba wax. Sure enough, they all showed this non-mixing effect. However, when we tested candies that do not have wax listed in the ingredients (M&M’s) the same effect was observed!

I’m interested in a couple of things regarding this experiment. First, I’m curious as to why this non-mixing effect occurs. I’m wondering if any of you have any ideas why the colors tend to stay in their own particular region in the water. We have noticed that, given enough time, the colors will bleed together.  But even after very long periods of time, semi-distinct regions of colors are observed. Second, I’m wondering if any of you have any ideas for modifications on this experiment, and how these modifications might be used to illustrate chemical principles. For example, I have found one video online which shows that the temperature of the water affects the rate at which the dyes spread out from the candies – what a great way to demonstrate the kinetic-molecular theory!  

Comments

Erica Jacobsen's picture
Submitted by Erica Jacobsen on

This would be a great activity to use with students for the 2014 National Chemistry Week theme of candy. I wondered what would happen if the candy pieces, after dissolving a portion of the coating, were transferred to another container and water added again to continue the dissolving process. If there is an outer wax coating that's causing it, perhaps after it's largely gone, the effects would change. Students could ask so many questions about this—a good system to investigate further. A great opportunity for experimental design.

Tom Kuntzleman's picture
Submitted by Tom Kuntzleman on

Hi Erica:

Your experimental suggestion is a good one.  Let me know what happens if you try it.  Your comments bring two questions to mind.  First, I wonder what would happen if this experiment were repeated with a non polar solvent such as  isopropyl alcohol instead of water.  My second question is only tangentially related.  You mention that the 2014 NCW theme is candy.  What is the theme for 2013?  And how does one go about finding out what the theme is for NCW for the current or future years?

Tom Kuntzleman

Erica Jacobsen's picture
Submitted by Erica Jacobsen on

Interesting idea with the isopropyl alcohol—nice that it's an easy consumer chemical.

 

The 2013 NCW theme is energy, which ties in really nicely with your "And the Oscar Goes to...a Chemist!" JCE Classroom Activity and the hot dog demo. ACS keeps the NCW themes updated at http://www.acs.org/content/acs/en/education/outreach/ncw.html. There's a link on the page for future "NCW Dates and Themes." 2015 is color chemistry.

Tom Kuntzleman's picture
Submitted by Tom Kuntzleman on

Thanks, Erica.  Hey, I guess the M&M's experiment might also go well with the 2015 NCW week theme of color!

Tom Kuntzleman

Submitted by Benjamin Barth on

This is really neat!  It brings a couple questions to mind:

1) Are the coloring additives truly being dissolved? Or, is the mixture of coloring molecules applied as an emulsion or a colloid of some sort and it is actually bits of that emulsion/colloid that are being "dissolved" by the water solvent? If this were the case, it could be possible that the larger particles would rather not mix and would "bounce off" each other rather than mix together. One additive that could have caused this effect to disappear could have been soap which might be a strong enough surfactant to make everything mix. Emulsions are a common annoyance in working up many reactions and can often be combatted by increasing the ionic strength via addition of a brine solution. It could be interesting to see what happens upon addition of brine.  I keep going back and forth in my head with the logic of whether brine should make them mix better or worse... 

2) What happens to the coloring when the pH of the solution is changed?  Some of the coloring molecules are very similar to pH indicators.  It would be neat to change the color by causing a reaction.

3) Also, what is the time frame for these colors to remain separated? Is it indefinitely?  That time-frame may give some clues as to the type of particles that are mixing.

Interested to hear your thoughts!

Ben

Tom Kuntzleman's picture
Submitted by Tom Kuntzleman on

Good to hear from you, Ben.

Actually, I find that I am quite interested to hear YOUR thoughts.  I do not have much experience working with colloids and emulsions, and it appears that you do.  So your thoughts are quite edifying to me.  I think I'll soon be going to the store to buy some candies so I can try some of these ideas.  I hope you do the same and share some results with us.  I'd be very interested to see what we discover.

The colors do not stay separated indefinitely.  They mix quite easily; bumping the plate repeatedly causes the colors to mix.  If I remember correctly, the colors stay separate for 5 - 10 minutes.  How long it takes for the colors to smear depends on temperature.   

Tom Kuntzleman

Erica Jacobsen's picture
Submitted by Erica Jacobsen on

I've been noodling around with this experiment this week, preparing some NCW materials for the ChemClubs. I hope to put together a video (with my limited equipment) of some of the things I did and write a post about it. I noticed today that the Steve Spangler link now has its carnauba explanation deleted. Interesting.

Tom Kuntzleman's picture
Submitted by Tom Kuntzleman on

I look forward to seeing your post and video.   I am interested to see what you have discovered!  If you haven't already, you should look through the comments section to this post, specifically the comments by Ben Barth.  He has some interesting suggestions.  I will be having one of my General Chemistry students playing around with this experiment for her end of year project.  I hope we can learn some more about this experiment, too.  Thanks for the update on the Steve Spangler link.  That is interesting...

Tom Kuntzleman

Lowell Thomson's picture
Submitted by Lowell Thomson on

Thanks for the post and the comments to get my brain thinking!

I've got a grade 10 introductory class that is just starting to discuss solutions. So we're going to try some inquiry tomorrow and see what happens. I'm sure we'll be taking some pictures and/or video, which I'll be sure to share. My hope is to have the students develop research questions, which we can then turn into experimental designs for further testing.

I'll keep you posted.

Lowell

Lowell Thomson
@ThomsonScience
IB Chemistry Teacher
American International School of Bucharest

Submitted by William Farmer on

Hi,

 

I'm watching this one after an e-mail I've got and see a lot of nice things I want to use in class. But the explantion...

Thinking about the experiment brought me to the idea of other solutions that don't really mix. There is a very common one; Fresh water and salty water.

So thinking like that, I came up with a suggestion like osmotic pressure. In that I reason from what the force behind the going into solution from the colouring agent is.

Is dissolves because the is "room" between the water molecules. It moves to the lower concentration zones. Until it meets a zone in the same concentration. Now the only reason for mixing is the movement of the molecules (kinetic theory, Brownian Movement). The influence of that one with the large molecules of the colours, is relatively low. So that one will take time.

What do you think?

William

Chemistry Teacher

The Netherlands

Tom Kuntzleman's picture
Submitted by Tom Kuntzleman on

Hi William

You state that the colors first spread out as a result of osmosis or diffusion.  However, when the different dyes meet each other (say red meets green), diffusion becomes limited because both the red region and green region are "filled" with large dye molecules. 

How do you think we could test this idea?  One experiment I have tried is using all M & M's of the same color in the different regions.  When this is done, the separation boundaries are still observed.  I think this experiment is consistent with your proposal.  

You might want to check out Erica Jacobsen's recent post on this topic:  http://www.jce.divched.org/blog/more-explorations-gobstoppers .  

I hope that by working together, we will solve the mystery of why the colors don't mix!   

Tom Kuntzleman

Submitted by William Farmer on

Yes, I would like to find out how it works.

It could be so that the colour travels along with the sugar. That it is the sugar that dissolves. That would be easy to check, by using only a sugarcube (or maybe some aspratame) instead of a candy....

Or otherwise a bit of salt instead of a candy. That might prove something.

William.