In a previous video, I showed you how to make a mini forge where you could heat metal for all kinds of weekend projects. Well, in this video, I’m going to show you how to use it for a fun science experiment. So go ahead and fire it up!
Using some long pliers, take a quarter and insert it into the mini forge. You’ll want to rotate it every few seconds to heat it evenly. After about 20 seconds it should be glowing red, to avoid over heating it, you’ll want to remove it at this point. Immediately drop the quarter into a 100 ml beaker filled with roughly 60 ml of methanol. It will begin to boil vigorously and then slow down to almost nothing, only to start boiling again in one short burst.
Watching the process again from the top. Watch how quickly the methanol boils; as its boiling point is only 148 degrees Fahrenheit, where the coin we’re dropping in is over 1200 degrees Fahrenheit! During the cooling process, some of the inner copper core of the coin has migrated to the outside, leaving you with a cool copper plated quarter! OK guys. Let’s talk about what’s going on here. There’s two really cool principles. The first question you might have is why the methanol? Why not water? Well, what the methanol does, is it works like an oxidizer and without we’d just wind up with these really ugly black coins. So that’s what the methanol does.
OK. So the second effect we saw here is called the Leidenfrost effect and its very cool. Its what caused that double boiling that we saw. This is where the coin gets a very thin vapor layer around it that actually protect the methanol from the high heat of the coin. Until it collapses. It doesn’t last very long and then we get that second boil as it reconnects. This is very similar to what we saw in the Mythbusters episode where they stuck their hand into the molten lead and pulled it out and they didn’t get burned, because they had that vapor layer around their hand caused by the boiling water. That’s called the Leidenfrost effect and its very cool.
Well I hope you enjoy your new copper quarter and if you enjoyed this video, like and subscribing to my channel on YouTube. Thanks for watching!