Baking soda is a common household item sold in any grocery store. It has the effect of neutralizing acidic chemicals.
But I am afraid Ben_Bovas is correct - what has been done cannot be undone. The best thing you can get from this experience is what you have learned about using acid on coins. Don't do it.
As a general rule cleaning or conserving coins in any manner is not a good idea. Especially when undertaken by the inexperienced and many times even by the very experienced. It is all too easy to ruin a coin and destroy any numismatic value it may have.
I would suggest that you read this article about the proper handling of coins -
Proper Handling
There are a great many other informative articles available on the Coin World site - read them. Just type a key word into the Search box and hit the Enter key on your keyboard.
