making volcanoes

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making volcanoes
By Sandra

Hi... If you mean baking soda and vinegar volcanoes, I can tell you how. I use a ketchup bottle (or you could use a salad dressing bottle). Put just enough baking soda to cover the bottom. Squirt in a squirt of dish detergent.
Fill a graduated cylinder (or other measuring device) with about 90 mL of vinegar. Add a few drops of food colouring if you want coloured lava.
When you are ready, quickly pour the vinegar into the ketchup bottle. (Pour it down the SIDE of the bottle so it's only hitting a small amount of the soda.) As soon as it's in, it will start to bubble. Cover the top of the bottle

with the palm of your hand(s) and hold it there until you feel a lot of pressure building up- say about 15-20 sec. You can shake it a bit too. It's fun to have the kids count down from 10 and then you let go, jump back and watch the lava shoot out. It will probably hit the ceiling.

You can compare this system to an actual cinder cone volcano. There's a chemical reaction (carbon dioxide gas is produced, just like in a volcano). Pressure builds up and when a crack forms in the neck of the volcano, the lava escapes. The magma chamber = the bottom of the bottle. (Plus if you want to demonstrate a SHIELD volcano, like the Hawaaian ones, you don't put your hand over top... you just let the lava gently bubble out.)

Hope this is what you wanted. I've done it successfully many times. You may want to practice it ahead of time to ensure you can do it for the kids. I've let the kids try it too, as long as you have a lab coat handy!