Cool Science: Spoons and Dry Ice
Jul. 26th, 2009 11:59 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
mbarkerOne of the late night quiz shows here in Japan posed the interesting question to their panelists:
If you lay a spoon on a block of dry ice, what happens?
Have you got your choice? Will a spoon lying on a block of dry ice produce gas, bend, ring, or jump?
As demonstrated live by the panel with a professor from University of Tokyo, the answer is that it will ring like a bell. The panelists carefully put on gloves and laid ordinary spoons on a block of dry ice. Just as you would set them in a place setting. And the spoons rang!
The professor explained that what is actually happening is that dry ice is somewhere around -80 centigrade, while the spoons are about 20 centigrade. This hundred degree difference causes the dry ice to produce gas very quickly, lifting the spoon slightly -- and the gas escapes. So the spoon drops again. The speed of this reaction, bouncing the spoon on sublimating CO2, is fast enough that it produces the ringing sound.
He didn't explain, but I think number one is wrong because CO2 is not visible. The spoons didn't bend. I suppose we could argue that the spoon is jumping into the air just a little bit and falling back, so number four is not completely wrong. However, even close-ups of the spoons laying on the block of dry ice didn't really show the motion, so it's not a particularly visible jump. It's just an audible ringing.
I have to admit, I started wondering if you could make a musical instrument, using different spoons to produce different tones. Perhaps not particularly practical, but it might be fun.
The show ended that segment with warnings that if you are going to play with dry ice, wear gloves! -80 degrees can do bad things to your hands, too.
If you lay a spoon on a block of dry ice, what happens?
- A visible gas is produced
- The spoon bends
- The spoon rings like a bell
- The spoon jumps into the air
Have you got your choice? Will a spoon lying on a block of dry ice produce gas, bend, ring, or jump?
As demonstrated live by the panel with a professor from University of Tokyo, the answer is that it will ring like a bell. The panelists carefully put on gloves and laid ordinary spoons on a block of dry ice. Just as you would set them in a place setting. And the spoons rang!
The professor explained that what is actually happening is that dry ice is somewhere around -80 centigrade, while the spoons are about 20 centigrade. This hundred degree difference causes the dry ice to produce gas very quickly, lifting the spoon slightly -- and the gas escapes. So the spoon drops again. The speed of this reaction, bouncing the spoon on sublimating CO2, is fast enough that it produces the ringing sound.
He didn't explain, but I think number one is wrong because CO2 is not visible. The spoons didn't bend. I suppose we could argue that the spoon is jumping into the air just a little bit and falling back, so number four is not completely wrong. However, even close-ups of the spoons laying on the block of dry ice didn't really show the motion, so it's not a particularly visible jump. It's just an audible ringing.
I have to admit, I started wondering if you could make a musical instrument, using different spoons to produce different tones. Perhaps not particularly practical, but it might be fun.
The show ended that segment with warnings that if you are going to play with dry ice, wear gloves! -80 degrees can do bad things to your hands, too.
