[Noobert]

We did a lab in chemistry where we changed copper pennies to "silver" and "gold" pennies.  First we mixed zinc with a beaker of sodium hydroxide.Then we put the bunson burner under it. After that we put the pennies in and left them there for about a minute. Then you drop t hem in water and you clean them and you have your silver penny. THen take another silver penny and put it into the bunson burner flame and it will turn gold.

I understand these where physical changes not chemical changes... But I do not exactly know what happened... could someone help me? THanks.

[Noobert]

Can anyone explain why the pennies go throught this change?

[skyjumper]

OK. Step 1: Your coating the penny "plating" it in zinc. Zinc looks silver, Silver penny.

Step 2: By heating the penny you are fusing the two metals into bronze (I think thats the alloy) Wich is a composite of Zinc and copper.

[Noobert]

Thanks, but are you sure that is correct?

[Noobert]

because I thought no chemical changes occured?

[skyjumper]

Well an alloy is defined as a group of elements in a metal-Matrix which is a chemical change...

[Borek]

Well an alloy is defined as a group of elements in a metal-Matrix which is a chemical change...

I would say most alloys are just mixtures, so there is no chemical change.

[FreeTheBee]

The copper and zinc alloy is brass. Bronze consists of copper and tin.
Although, it seems in English the terms are sometimes used interchangeably.

[skyjumper]

I knew it started with a b...