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July 25, 2014

Homework Help: Honors Chemistry

Posted by Emily on Wednesday, October 7, 2009 at 12:01am.

We did the gold penny lab, where we bathed a copper penny in a hot zinc-NaOH mixture to turn it a silver color, then we heated that in a flame to turn it a gold color. There are two questions that go with this lab that I don't understand, however:

4. Did the copper and zinc undergo a physical change or a chemical change when the penny was bathed in the zinc-NaOH solution? Explain your answer.

- I would put it was a physical change because the zinc pretty much just melted onto the penny to turn it a silver color -- is this right?

5. Did the copper and zinc undergo a physical change or a chemical change when the penny was heated in the flame? Explain your answer.

- Wouldn't you also put it was a physical change because the zinc mixed with the copper of the penny to turn a gold color? Or did I get this completely backwards?

Any help is GREATLY appreciated! :D

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