Did you want those nice long answers single or double spaced, Isaiah? Teachers beg us to just tell you to do your own homework :-)

Ted Mooney, P.E. 
finishing.com
Brick, New Jersey

Sigh.. another student that just wants to cut and paste and turn it in to a teacher. Isaiah, do a search on this site, and you will find the answer to your question...or read one of your science books, or better yet, pay attention in class.

Marc Green anodizer - Boise, ID, USA

Study or else you'll end up in one of those mines inhabited by Orcs in Middle Earth.

Tom Pullizzi Platronica.com Falls Township, PA

First of all dull and dirty pennies have a layer of copper oxide (copper and oxygen mixed together) and that can be dissolved by a weak acid. Lemon juice is a weak acid so is orange juice and vinegar.

Jennifer C
- Moncks Corner, SC, U.S.

Lemon juice cleans pennies better than bleach because bleach takes out stains from things that have pores or spaces for things to live but pennies are solid things that don't have alot of pores and stuff. And acid which is in the lemon juice dissolves things on the surface and that's why lemon juices works better than bleach.

Carmella C.
- PC, NY, USA

Ted Mooney, P.E.  finishing.com Brick, New Jersey