Comments on: All you wanted to know about nanotechnology, from a pack of Mentos and a bottle of Coke http://2020science.org/2009/01/25/nanotechnology-mentos-coke/ Providing a clear perspective on developing science and technology responsibly Thu, 09 Feb 2012 16:00:29 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Jeff http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-138135 Jeff Tue, 28 Jun 2011 13:35:01 +0000 http://2020science.org/?p=794#comment-138135 Andrew, The best demonstration i have been able to come up with has been how particle size changes the optical properties of a material. Here is the setup: dilute suspension of 20 nm Ag np (PVP capped work great) in DI water The suspension is yellow. Add some salt water around 15 ppthousand. Because of the higher ionic concentration, the collapse of the double layer occurs. This in turn overwhelms the van der walls interaction and the particles start to agglomerate. As the particle agglomeration increases in size, the color of the solution changes from yellow to red to blue to gray, then BAM! the particles get too big and fall out of solution. Its a bit complex to explain, but fun. It can also be used to describe how size impacts the optical properties. J Andrew,

The best demonstration i have been able to come up with has been how particle size changes the optical properties of a material. Here is the setup:

dilute suspension of 20 nm Ag np (PVP capped work great) in DI water

The suspension is yellow.

Add some salt water around 15 ppthousand. Because of the higher ionic concentration, the collapse of the double layer occurs. This in turn overwhelms the van der walls interaction and the particles start to agglomerate.

As the particle agglomeration increases in size, the color of the solution changes from yellow to red to blue to gray, then BAM! the particles get too big and fall out of solution.

Its a bit complex to explain, but fun. It can also be used to describe how size impacts the optical properties.

J

]]> By: Luisa Filipponi http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-114459 Luisa Filipponi Sun, 13 Mar 2011 16:59:38 +0000 http://2020science.org/?p=794#comment-114459 It has been a while since you posted this, and I am still thinking about it :-) Few days ago I was watching the (brilliant) videos provided by the NISE Network and in one they did this simple demonstration: a piece of iron vs. iron powder dropped in two bottles of Diet Coke. Only in the second case you get the "geyser" effect. So here the effect is clearly connected with the size of the material. Which makes the Mentos case even more intriguing- it definitively must be connected to its surface (chemistry+topography). Indeed, I tried to remove the outer layer of the Mentos (ehm, got my daughter to help me..) and the effect is lost. How interesting! Luisa It has been a while since you posted this, and I am still thinking about it :-) Few days ago I was watching the (brilliant) videos provided by the NISE Network and in one they did this simple demonstration: a piece of iron vs. iron powder dropped in two bottles of Diet Coke. Only in the second case you get the “geyser” effect. So here the effect is clearly connected with the size of the material. Which makes the Mentos case even more intriguing- it definitively must be connected to its surface (chemistry+topography). Indeed, I tried to remove the outer layer of the Mentos (ehm, got my daughter to help me..) and the effect is lost. How interesting! Luisa

]]> By: bob dylan http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-111346 bob dylan Fri, 18 Feb 2011 20:13:36 +0000 http://2020science.org/?p=794#comment-111346 I like Cheese!!! I like Cheese!!!

]]> By: Luisa Filipponi http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-35278 Luisa Filipponi Wed, 04 Nov 2009 13:44:32 +0000 http://2020science.org/?p=794#comment-35278 Thanks for the ideas. I have something in mind ...will let you know if it works! Sure this experiment is fun...a good message in itself on what science can be. Thanks for the ideas. I have something in mind …will let you know if it works! Sure this experiment is fun…a good message in itself on what science can be.

]]> By: Andrew Maynard http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-34971 Andrew Maynard Mon, 02 Nov 2009 16:04:36 +0000 http://2020science.org/?p=794#comment-34971 Hi Luisa, There is no actual nano here obviously, but the "lesson" is that things behave differently when they are made smaller. In this case, the hypothesis is that smaller Mentos particles will have a higher overall surface area, and will therefore lead to a more rigorous reaction with the Coke. As it turns out, things are more complex than this - which probably means that it forms a great platform for some investigative science. So you start out with the original hypothesis and test it. You then begin explore why you didn't get the results you were expecting - is it the surface roughness or the surface coating of the Mentos that is important? (Try the experiment after the surface has been washed off). Is it the speed with which the whole Mentos reach the bottom of the container? (Devise a way of releasing crushed Mentos directly into the bottom of the bottle). And so on. Then, while the link to nano is clearly that size matters, you have a great framework for developing a better understanding of how science works. Hi Luisa,

There is no actual nano here obviously, but the “lesson” is that things behave differently when they are made smaller. In this case, the hypothesis is that smaller Mentos particles will have a higher overall surface area, and will therefore lead to a more rigorous reaction with the Coke. As it turns out, things are more complex than this – which probably means that it forms a great platform for some investigative science.

So you start out with the original hypothesis and test it. You then begin explore why you didn’t get the results you were expecting – is it the surface roughness or the surface coating of the Mentos that is important? (Try the experiment after the surface has been washed off). Is it the speed with which the whole Mentos reach the bottom of the container? (Devise a way of releasing crushed Mentos directly into the bottom of the bottle). And so on.

Then, while the link to nano is clearly that size matters, you have a great framework for developing a better understanding of how science works.

]]> By: Luisa Filipponi http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-34963 Luisa Filipponi Mon, 02 Nov 2009 14:46:26 +0000 http://2020science.org/?p=794#comment-34963 Hi Andrew, thanks for sharing this. I am involved in nanotech education and always look for new ways of communicating nano. This looks like a fun one! In this experiment it seems like nano-surface roughness could play a role, together with chemistry. But if a kid asks "where is the nano-stuff in here?" I am not sure I could have a good answer. Also as you say crushing the mentos into a fine powder does not increase the effect. I read somewhere that this has to do to the fact that the speed at which the mentos reaches the bottom of the bottle infleunces the effect, and when it is a fine powder it goes down very slowly... My question to you is: how would you make this experiment more "scientific" so to be used in a class where the aim is to teach some fundamental nano-effects? Any ideas?? Thanks :-) Hi Andrew, thanks for sharing this. I am involved in nanotech education and always look for new ways of communicating nano. This looks like a fun one! In this experiment it seems like nano-surface roughness could play a role, together with chemistry. But if a kid asks “where is the nano-stuff in here?” I am not sure I could have a good answer. Also as you say crushing the mentos into a fine powder does not increase the effect. I read somewhere that this has to do to the fact that the speed at which the mentos reaches the bottom of the bottle infleunces the effect, and when it is a fine powder it goes down very slowly…

My question to you is: how would you make this experiment more “scientific” so to be used in a class where the aim is to teach some fundamental nano-effects? Any ideas?? Thanks :-)

]]> By: Andrew Maynard http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-889 Andrew Maynard Fri, 20 Feb 2009 01:49:30 +0000 http://2020science.org/?p=794#comment-889 Thanks - sorted :-) Thanks – sorted :-)

]]> By: G http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-888 G Fri, 20 Feb 2009 01:10:33 +0000 http://2020science.org/?p=794#comment-888 FYI - Typo in line 2 - ts --> its FYI – Typo in line 2 – ts –> its

]]> By: Pop Science? | TNTlog http://2020science.org/2009/01/25/nanotechnology-mentos-coke/#comment-204 Pop Science? | TNTlog Mon, 26 Jan 2009 09:32:35 +0000 http://2020science.org/?p=794#comment-204 [...] time I’m at a wedding I’ll take a packet of Mentos with me. As Andrew Maynard demonstrates here, the importance of size to chemical reactions can be easily demonstrated using some diet coke, some [...] [...] time I’m at a wedding I’ll take a packet of Mentos with me. As Andrew Maynard demonstrates here, the importance of size to chemical reactions can be easily demonstrated using some diet coke, some [...]

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