Coke Explosion

[Melanie]

Okay, just a bit of fun - here's a link to that viral advertising thing featuring the wonders of Mentos and exploding coke.

http://video.google.com/videoplay?docid=-1450915772177922792

Hint - don't try this indoors!!

Layman's explanation of how this works so excellently would be read with interest!

For some reason this reminds me of making rubber eggs when my kids were small - soak an egg in a mug of vinegar for a couple of days and the calcium (I assume) is leached out, leaving a fascinatingly squashy egg-shell.

Any other Boy's Own tricks out there? I have grand-daughters I need to impress...


Melanie.

[Aardvark]

Smoke and egg shell with a candle until it turns black. Drop it in salt water and from memmory it should look silver not black.

[Melanie]

Thanks! I'll try that one...

[Melanie]

Ha! Just tried it, with the able assistance of 25 yr old son Oz - he handled the salt water bit and I smoked the egg... abject failure the first time, not enough carbon on the egg, not enough salt in the water - and I don't think warm water is ideal... Never beaten, (ooh sorry, no pun intended) we washed the egg and re-smoked it, the bowl was emptied and refilled with cold water and Lots of salt, the egg was duly immersed, turned silver and Oz and I chorused 'Woah!!!' (That's Woah, not Woo...)

Fantastic bit of fun, thanks a lot Aardvark. Silver eggs! Can't wait to show my granddaughters.

[median]

Mel

Didn't know the exact composition of Mentos but hey, didn't need them ;D

Wilkpedia
The science behind it
Many theories are being debated as to the exact scientific explaination of the phenomenon. However many scientist claim that it is a physical reaction and not a chemical one[3]. Water molecules strongly attract each other, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. To form a new bubble water molecules must push away from one another. It takes extra energy to break this surface tension. So, in other words, water resists the expansion of bubbles in the soda.

When Mentos are dropped into soda, the gelatin and gum arabic of the candy dissolves and breaks the surface tension. This disturbs the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites, perfect places for carbon dioxide bubbles to form. As soon as the Mentos enter the soda, bubbles form all over the surface of the candy.

Also the Mentos candies are heavy and sink to the bottom of the bottle so when all this gas is released, it literally pushes all of the liquid up and out of the bottle in a blast of soda.



Will still look at the ingredients though. If the gum arabic and gelatin are crucial we should be able to replicate with similarly composed sweets O0

[Mongrel]

Trebor Spearmint imperials do a fine job IIRC

Oh, and the rubber egg experiment can be done with bones as well, I'd suggest a chicken leg and it'll take 4-6 days in a good malt vinegar ;)

Other home experiments include;
Egg in a bottle - Wide necked (but smaller than a shelled, hard boiled egg) bottle, small piece of burning cotton wool in the bottle, egg on top. As the cotton wool burns the low pressure will suck the egg in without breaking it.

Empty treacle tin and gentle heat - the gas will expand to the point were the lid pops off dramatically. (Goggles and 6ft clearance highly recommended)

Pinhole cameras - easy to make or I've seen a few different varieties in toy shops for under a tenner

Floating Needle compass - one of the classics, when that gets boring a drop of soap\detergent turns it into a surface tension lesson

That's all I've got for the moment, I'll dig around for some more :)

[tkingdoll]

This is my favourite Diet Coke and mentos vid, they recreate the Bellagio fountain:

http://eepybird.com/index.html

[doubting thomas]

Here's a simple thing to do and doesn't require any equipment whatsoever.

Get them to stand with their backs against a wall with feet touching the skirting board, then bet them that they can't touch their toes without falling over.

They will try this several times before giving up, it can't be done. ;D ;D

[tkingdoll]

Here's a simple thing to do and doesn't require any equipment whatsoever.

Get them to stand with their backs against a wall with feet touching the skirting board, then bet them that they can't touch their toes without falling over.

They will try this several times before giving up, it can't be done. ;D ;D


Hee hee, I couldn't take your word for it and had to try. ;D

[huw-l]

coke and mentos bottle rockets O0

http://www.youtube.com/watch?v=U1QLQtdtte0

[Melanie]

;D ;D ;D

Thanks so much everybody! I've already made sure both girls can read like demons; now it's time to show them 'science can be fun'. Excellent.

Am saving the standing-against-the-wall-and-touching-toes one for my son. He deserves it. :)

[seren]

If he deserves that you could try the touching-your-elbow-with-your-tongue one on him too. It somehow feels like you should be able to...


Edited to add when I was a kid I liked gyroscopes on a piece of string, and coke-bottle rockets powered by water pressure.

[seren]

Oh, and don't do this:

http://www.funmansion.com/html/Do-Not-Microwave.html

[Melanie]

Adam and Joe! I'd forgotten all about them. Thanks for that one!