I'm doing a science project and I need to know the scientific explanation of how vinegar and salt affect copper pennies.
A copper penny looses its bright original shine because with time, the copper metal on the surface of the penny reacts with the oxygen in the air to form a dull brown copper oxide tarnish. Placing them in a vinegar salt (table salt or sodium chloride) is a way to restore the shine on dull pennies. The acetic acid in vinegar dissolves the copper oxide layer on the surface of the coin thus exposing the bright copper metal underneath. The reaction occurs much quicker if you add a little salt to the vinegar.
Vinegar is an acid and will corrode copper......salt has a similar corrosive action..
vinegar is ethanoic acid, and acids and metals react in this general way: metal + acid --> salt + hydrogen gas so in this case the vinegar is going to react with your copper and turn it into hydrogen gas and Copper(II) acetate (the salt in this situation) the effect of salt on the copper depends on what salt you are using, as some salts can be acidic and other basic etc etc
