The kids and I thought we'd share the pros and cons some of our summer amusements in case you're thinking of trying them.
The Diet Coke - Mentos Geyser
Have you heard of this little experiment? The Mentos cause the carbon dioxide gas (the soda carbonation) to escape. Whether or not this is a chemical or physical reaction is under debate by scientists, and you can read about what happens in this experiment at one of my favorite kid sites, Steve Spangler Science. Apparently this experiment will work with non-diet soda but the diet version creates a less sticky explosion.
Buy a two-liter bottle of Diet Coke and a pack of Mentos mints. (I bought two of both.)
If you want to get a picture of this, put your camera on the right setting and set it away from the experiment before you get started! (I clearly didn't set my camera first because my action shots are blurry.) This would be fun to video too! Oh - and if you have a dog - make sure to keep him in the house until you're done with your explosion because he'll be drawn to that bottle of Diet Coke like a moth to a flame (speaking from experience here!!)
Set the bottle in the middle of your yard or a field, in a flat spot. Open the bottle and the Mentos, and all at once, slide all of the Mentos into the bottle. (I tried this using a rolled piece of paper as the Steve Spangler site suggests, but Hannah had more luck putting them into a bottle directly from the package.)
It's important to know ahead of time that the entire package of Mentos need to go in all at once because you only get one explosion out of each 2 liter bottle - and the more Mentos that you get in there, the bigger the geyser will be. The geyser happens almost immediately so a swift motion of depositing the Mentos into the Diet Coke (and jumping out of the way!) is necessary.
If you drop the Mentos into the bottle properly, the Diet Coke will shoot up in the air several feet.
The kids tried to catch the Diet Coke in cups (and directly into the their mouths!).
Pros: kids of all ages think this is awesome /// for about 5 minutes you're the coolest mom ever /// there is actually something to be learned about chemical and physical reactions
Cons: the whole shebang takes about 5 minutes beginning to end /// for the length of time this activity amuses your kids there's not a lot of bang for the buck as far as mom is concerned (about $7 for two geysers)
Worth The Time/Effort/Money?: Mom - yes (once!), Kids - yes!!!