money

[ydoaPs]

i got my new toy today(bought it on ebay sunday). it is a small butane torch.

i melted a penny with it. the coating completely vaporized and the inside(zinc?) melted and such. when i tried to melt a dime, however, it didn't melt. every part of the dime, except where the flame actually touched it, changed colours(multiple times). what causes the discolouration?

[JPQuiceno]

chemical reaction when the materials composing the dime are heated. IDK im guessing

[akcapr]

just different rates of cooling/heating or something

[jdurg]

Pennies are made out of a relatively pure zinc core with a very thin copper layer/plating on the outside. Dimes, Half Dollar and Quarters are composed of a solid copper core with an outer layer of a copper/nickel alloy. With the penny, the Cu coating is so thin that what happened is you quickly oxidized the copper and the heat caused the oxides that formed to quickly vanish away leaving the low melting zinc inside. What may have also happened is that the liquid zinc dissolved the copper. On the dime, it's just a simple manner of oxidation of the Cu/Ni layer as the torch isn't hot enough to melt the copper.

[jowrose]

Dimes half dollars and quarters all have a copper core? ah, that makes sense now. I was trying to melt some quarters with some thermite i have (it kinda worked...) and when it had all cooled off i noticed one of the quarters looked like it was oozing copper. I was confused, copper is definitely not one of the products of the thermite reaction... But i didn't think that quarters contained copper at all either. I've tried putting quarters on railroad tracks before and they still have the silver appearance even after being pounded on, so I figured they must be one single metal or alloy.

[coquina]

You should be careful not to breathe the fumes when you're melting metal.

[jdurg]

Just take a quarter/dime/half dollar and look at the sides. The Cu shows through clearly.

[jowrose]

oh yeah, you're right. now i feel stupid.

 

yeah, i know not to breath in the fumes. I always stand at least 20 feet back from the reaction. but i suppose that's more to avoid the flying bits of melted metal...