Electrochemisty - Silver and Aluminum??

Question

I saw this cleaning guide, which says that a good way to clean silver is to put it in a bucket with baking soda, aluminum foil, and warm water.

http://www.foodnetwork.com/food/ck_cg_cleaning_chart/0,2495,FOOD_19556,00.html

Do any of you chemistry geniuses know what kind of reaction this is? I was thinking it might be electrochemical, but now that I think about it, the baking soda is throwing me off.

BTW I was a biochemistry major in college and took 3 years of chemistry, but this is out of my league.

OMG. I had approximately 2 weeks of electrochemisty in general chem, way back in 2002. Excuse me for not remembering. The other chemistry classes I took after that were organic and physical chemistry, which I remember better but neither of which has anything to do with this.

At least I was on the right track eh?

Answer 1

When silver tarnishes, the silver combines with Sulfer to form Silver Sulfide, which is black. The reaction takes place as follows:
3Ag2S + 2Al ---> 6Ag + Al2S3
Think of the baking soda as the "salt bridge" for this reaction, for it is technically an electrochemical cell with Al being oxidized and the Ag being reduced. Aluminum is used because it has a greater affinity to Sulfer than silver.

Answer 2

Silver And Aluminum Reaction

Answer 3

This is an Oxidation-Reduction reaction or REDUX.

This is a "battery" type action and happens spontaneously. The tarnished silver is "oxidized". When the chemical reaction takes place it is "reduced" or gives up electrons and the aluminium is oxidized or turned into aluminum oxide. The baking soda is a "salt" and acts as a salt bridge to transfer the electrons from the silver oxide to the aluminium.

This is BASIC chemistry! This should NOT be out of your league if you are chem major!