High school chemistry put to task

(Half-done two toned silver vase with well-polished one in the background)

After experimenting so much with cooking, I decided to use my high school and undergrad chemistry knowledge to clean up some silverware I had. With a religious event coming up this Friday, these items are to be the show-piece and I wanted them spic and span.

Here is how it goes: Line the insides of a non-reactive bowl with some Aluminium foil. Place the tarnished silver (which is apparently silver sulphide)such that the tarnished part touches the foil. Add a generous spoon of baking soda. Pour boiling water on the silver and gather up the foil and close it like a bundle. After a minute or so, you can find your well-polished silver. When you open, you can smell the rotten egg stench of hydrogen sulfide.

Here is an explanation I found on the Internet for the reaction: " The hydrogen gas is evolved through the reaction of aluminum and sodium (bi)carbonate. The hydrogen plays no part in the removal of the silver tarnish (i.e., silver(I) sulfide).

Aluminum is a reducing agent, and thereby reduces silver sulfide to elemental silver while forming aluminum sulfide (which is yellow in color). The aluminum sulfide thus formed readily hydrolyzes to form aluminum hydroxide and hydrogen sulfide.

So, we really have *two* gasses evolved: hydrogen and hydrogen sulfide..."

With such a neat trick that is effortless, brain obviously wins over brawn.