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Q & A: melting and boiling metals

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Most recent answer: 11/12/2014
Q:
Because it is possible to cool a gas to the point where it where it would become a liquid, and then to a solid, would it be possible to melt a metal, such as gold, and get a high enough temp. where it would boil and turn into a gas?
- Michael (age 14)
Green Bay, WI, USA
A:

Great question.

Yes, absolutely. Metals are melted all the time in industrial processes where the molten metal is poured into some mold to give it a shape. That works for even for iron alloys that have much higher melting points than gold. As for turning gold into a vapor (gas), that's something we routinely do in the lab. We do it to put thin layers of gold on other materials to make nice electrical contacts. The standard way to do it is to make a little boat out of a metal that has a higher melting point than the boiling point of gold. Then a big electrical current is run through the boat to get it so hot that the gold melts and a lot of it evaporates. The vapor cools when  it hits a surface and leaves a nice little coat of solid gold.

The wikipedia article on gold gives its melting and boiling points: . The articles on other elements do the same for them. You can see from the article on tungsten that its melting point is higher than gold's boiling point, so it can be used for the little evaporation boats.

Mike W.


(published on 11/12/2014)

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