Celebrate Chemistry Week with Lava…

6 10 2011

…in a cup! 

Did you know that volcanoes are just a bunch of lava?

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. Volcanoes form after the eruption of molten lava cools and leaves a raised platform, after repeated eruptions the volcano gets bigger and bigger. We find lava and volcanoes endlessly interesting here at ACM, we even have a featured volcano in our current exhibit Dinosaurs: Land of Fire and Ice.

So what’s happening in this experiment? First of all, the oil floats on top of the water because it is lighter (less dense) than the water. Since the salt is heavier (or more dense) than oil, it sinks down into the water and takes some oil with it, but then the salt dissolves and the oil heads back to the top.

The lava in the cup is demonstrating something you might learn in chemistry class: density. Density refers to mass per unit volume of an object. Most objects have a fixed density, however temperature sometimes can affect this. For example, as lava cools it becomes harder and more dense, neat huh?

If you like this experiment, then you should check out the Museum on Sunday, October 9th, where you can get your hands on your own chemistry activities in honor of National Chemistry Week!

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