Have you ever seen a tarnished piece of silver? Over time, a chemical reaction takes place that causes a tarnish to appear on purely silver items. The chemical, silver sulfide (Ag2S), is the compound responsible making silver appear grayish. While there are many products you can purchase to remove the silver tarnish, a solution of baking soda and salt poured into an aluminum pie pan works effectively. The baking soda and salt solution reacts with the silver sulfide, pulling the sulfur atoms out and "plating" them onto the aluminum as aluminum sulfide. The silver that remains from the reaction is re-deposited onto the silver. This is a type of replacement reaction. The sulfur atoms replace the aluminum atoms in the aluminum foil and leave behind just silver. Do not rush to your kitchen and start polishing any silver items just yet. You will need check with an adult first, as some items require professional cleanings to retain value.