i need help with a chemistry lab.?

Question

we cleaned a penny, and put it in a sodium hydroxide-zinc mixture over a bunsen burner. it turned silver. then we took it out, and just held it over the flame with tongs, and it turned gold.
Here are some questions i have:

1. did the copper change to gold? explain. (i put no, and my reasoning was "you told us it wasn't"...i didn't actually know)
2. what intensive property could be used to prove your explanation? (i dont know this either)
3. list 1 extensive and 1 intensive property of the token
4. the last change formed an alloy, was the last change physical or chemical?
5. did the last change form a compound, mixture, or new element?
6. what was the final product? ( i think its brass but idk)

i need help figuring these out, but i would like a good explanation so im actually learning something

Please, I need help, I don't understand this!!

Answer 1

1. No, the copper didn't change to gold. Transmutation is extremely difficult to achieve, and requires sophisticated manipulation of the nucleus of an atom. It occurs only among a few well-known radioactive elements or in the core of a star. You definitely can't transmute copper over a Bunsen burner. Besides, to skip ahead to answer 6, the surface of the penny turned to brass, not gold.

2. Density. If you measured the mass and volume of the penny and used it to calculate the penny's density, it would not be equal to the density of gold.

3. Extensive property: mass. Intensive property: density.

4. Physical. Formation of alloys is a physical change.

5. It formed a mixture. And to shed more light on answer 4, an alloy is a type of mixture, and formation of mixtures is always a physical change, even when the mixture is homogenous.

6. You are correct; it is brass.

Answer 2

1. the copper did not change into gold... and you are correct it's brass... an alloy of copper and zinc.... the silver you observed is the zinc that plated the copper... after heat was applied the two metals mixed together forming the alloy.
2. remember archimedes? eureka! use density to prove that it is not gold. pure gold will have a different density with your alloy.
3. intensive property: density
extensive properties: mass and volume
4. it is just physical change... nothing happened to the metal chemically; they just mixed together
5. it becomes a mixture
6. and yes, it's brass

Answer 3

It depends on your particular taste in classes. If you are more math/science person, chemistry would be the better pick, as many calculations, equations, and the like are required. If you are more English/Literature oriented, Biology would be the better bet. I've always found Chemistry to be more fun, but I'm a Chemistry major, so the decision is biased